Health & Science

‘Alien’ life on Earth

Extraterrestrial life appears far more likely now that scientists have “trained’’ a form of bacteria to survive and grow on a diet of arsenic, in an environment lacking one of the building blocks thought essential to all forms of life. NASA astrobiologists isolated bacteria growing in the arsenic-rich mud of California’s Mono Lake and grew them in ever-decreasing concentrations of phosphorus. Phosphorus has been considered one of the elements necessary for life’s biochemistry, along with carbon, hydrogen, nitrogen, oxygen, and sulfur. Over just a few months in a phosphorus-free environment, the bacteria evolved to swap arsenic for phosphorus right down to its DNA—essentially becoming an alien life-form never before seen on Earth. “Life could be much more flexible than we generally assume or can imagine,’’ astrobiologist Felisa Wolfe-Simon tells New Scientist. The finding suggests that life could evolve on planets with environments previously deemed too harsh, says Gerald Joyce, a molecular biologist not involved with the study. “It gives us food for thought about what might be possible on another world,’’ he says.

Stress could defeat dieting

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As many people rediscover around this time of year, diets tend not to work for very long. One confounding factor may be stress, ScienceNOW reports. Neuroscientists at the University of Pennsylvania found that dieting seems to render lab mice more sensitive to stress and less able to resist the food cravings that it triggers. The mice were first put on a moderate diet that cut 10 percent to 15 percent of their weight. When they were exposed to stressful noises, the dieters’ blood had higher levels of the stress hormone cortisol than nondieters’ blood. Those levels remained elevated even after the mice were taken off their diets and returned to normal weight. When subjected anew to mild stress, the ex-dieters were more likely than a control group to soothe themselves by eating large amounts of high-fat food. “Dieting not only increases stress, making successful dieting more difficult,” says lead researcher Tracy Bale. “It may actually ‘reprogram’ how the brain responds to future stress and emotional drives for food.’’ Further studies will be needed to see whether the underlying mechanisms also apply to humans. If they do, they may establish stress as a reason why some persistent dieters struggle to maintain their weight loss.

Wine allergies explained

About 8 percent of the population has an allergic reaction to wine, suffering congestion, headaches, or more severe symptoms like hives or breathing difficulties. Sulfites account for a small fraction of those allergies, but now scientists think they have located the culprit in the vast majority of cases: glycoproteins, the sugary protein molecules that form as grapes ferment. Researchers in Denmark isolated 28 glycoproteins in an Italian Chardonnay and then broke them into tinier peptides that could be easily analyzed. They noticed remarkable similarities to known allergens found in latex, pears, and ragweed. “If these molecules are proven to be responsible for allergy in wine, then the winemakers will have a target to remove them,” molecular biologist Giuseppe Palmisano, the study’s lead author, tells MSNBC.com. But don’t expect to see hypoallergenic wines anytime soon. The problematic proteins vary among grape varieties and may bring other, more desirable attributes to wines. Removing them would be difficult and expensive, Joe Vinson, a chemistry professor at the University of Scranton, tells AOLHealth.com. “You can’t fuss around with every single grape.”

Animals, too, are getting obese

Like us, the animals in our midst are growing fatter. After analyzing data on some 20,000 mammals living in homes, in science labs, and in the wild near humans, researchers at the University of Alabama at Birmingham found that animal weights have risen across the board in recent decades. Some of that may be attributable to human behavior: It has long been suspected that we extend our excessive eating habits to our pets, and our high-caloric waste may have caused the weight of feral rats in Baltimore to balloon by 40 percent in the past 20 years. But that doesn’t explain the marked weight gain among marmosets, mice, and rats in labs, where diet is closely monitored. Researchers believe that some additional factors may be at work, which could include chemical additives, climate change, or an unusual virus that has been associated with obesity. “We can’t explain the changes in body weight by the fact that they eat out at restaurants more often,” lead author David Allison tells LiveScience.com, “or the fact that they get less physical education in schools.”