Woolly rhinos came down from the cold

Ice Age icons were pre-adapted to harsh climate, new fossils suggestWeb edition : Thursday, September 1st, 2011 COOL RHINOFossils of a new species of woolly rhino, shown here in an artist's reconstruction, have turned up in pre–Ice Age deposits high in the foothills of the Himalayas.Julie Naylor

A new trove of mammal fossils found high in the foothills of the Himalayas suggests that Tibet may have been a harsh, cold testing ground where woolly rhinos and other big mammals developed their cold-climate cool well before the Ice Age began.

Among the treasures from the Zanda Basin is the oldest fossil yet found of a woolly rhino, dating from about 3.7 million years ago, says vertebrate paleontologist Xiaoming Wang from the Natural History Museum of Los Angeles County. The complete skull and several neck vertebrae of the now extinct animal represent a new species, Coelodonta thibetana, Wang and his colleagues report in the Sept. 2 Science.

“It’s an important find,” says vertebrate paleontologist Donald R. Prothero of Occidental College in Los Angeles, who studies the evolution of mammals, including woolly rhinos. The paper is the first evidence for the idea that the lineage of the iconic Ice Age giant, and maybe other species, had already evolved cold-weather adaptations instead of developing them as the big chill set in 2.8 million years ago.

HIGH-ALTITUDE FINDSPaleontologists working in Tibet discovered the skull and lower jaw, shown here in a digital composite, of an ancient species of woolly rhino, Coelodonta thibetana.Image courtesy of Xiaoming Wang

When the Ice Age did come, descendants of the early Tibetan rhinos could have moved gradually off the plateau to lower altitudes throughout Eurasia. Wang and his colleagues note that fossil locations of three later woolly rhino species fit the pattern of a lineage that diversified down and out of the high plateau. “Tibet as a special environment probably is the cradle of some of the cold-adapted species of the Ice Age,” Wang concludes.

That’s a reasonable scenario, Prothero says. “I don’t think it’s been suggested before because there was no evidence for it.”

Wang and his colleagues found such evidence in the Zanda Basin, which sits 3,700 to 4,500 meters above sea level and is surrounded by even higher peaks. “It’s like working on top of Mount Whitney,” the highest peak in the contiguous United States, Wang says.

Toward the end of the field season in August 2007, Wang himself was exploring late in the afternoon a few miles from his colleagues when he stumbled onto a big piece of fossilized bone. Recognizing it as a vertebra, he swung his hammer at a promising spot — and uncovered a hint of what he calls the biggest discovery of his career. “Here is a tooth of a woolly rhino revealed by one single whack of my hammer,” he remembers.

Subtle characteristics identified the skull as a more ancestral species than later, Ice Age woolly rhinos. The Tibetan rhino already had such adaptations as a forward-leaning, flattened horn convenient for sweeping aside snow while foraging for food. The research team estimates the skull came from a mid-sized rhino about the size of today’s Indian and black rhinos. The fossils did not include hair, so paleontologists can only speculate about how woolly it might have been.

In addition to the newly named C. thibetana, the basin has also revealed other cold-adapted mammals whose descendants might have spread during the Ice Age, such as blue sheep and the Tibetan wild ass.

Some Ice Age mammals “probably came from high elevations and were pre-adapted to cold, but I wouldn’t want to say everything followed this pattern,” Prothero cautions. “In the real world nature is always more complex.”

Found in: Life

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Fighting flames with greener materials

New flame retardants rely on alternating nanolayers of relatively nontoxic materialsWeb edition : Wednesday, August 31st, 2011 FOAMING BUBBLESAn electron micrograph shows cotton fabric coated with 20 paired layers of chemicals before (left column) and after (right column) burning. Bubbles in the lower right photo show the coating’s heat-triggered foaming.Y.-C. Li et al/Advanced Materials 2011/Wiley-VCH Verlag

Materials scientists in Texas have developed flexible coatings mere billionths of a meter thick that keep cotton clothing from going up in flames and plastic foam from melting. Unlike the widely used but potentially toxic flame retardants they've been designed to replace, these nano-coatings appear relatively safe, their designers say.

Yu-Chin Li and Jaime Grunlan of Texas A&M University in College Station described their team’s new technologies August 31 at the American Chemical Society national meeting in Denver.

Because fabric fibers are so thin, “being able to fire-retard them is a big deal,” observes chemist Charles Wilkie of Marquette University in Milwaukee, a fire-retardant specialist not involved with the new work. “So I’m encouraged. The new work is impressive.”

Grunlan’s team has been seeking safer alternatives to brominated fire retardants, some of which have been banned over concerns about their potential toxic effects. The researchers’ initial prototypes consisted of alternating layers of garden variety clay and a commercial polymer. But the polymer, a synthetic chemical, did not rely on renewable, green constituents. So the engineers swapped it out for an inexpensive waste material: chitosan, a natural compound extracted from shrimp and lobster shells.

Like the earlier clay-based recipes the group had worked with, the new formulation proved disappointing on cotton fabric, Grunlan says. But it was a game changer for plastic foam, such as the type used as cushioning in furniture. Untreated foam held over a propane torch flame for 10 seconds quickly ignited, melted and burned up. But after applying 10 dual layers of clay and chitosan to an identical piece of foam, the 10-second flame created a thin veneer of char but left the interior unscathed.

Still intent on finding fabric protectants, the team turned to materials that intumesce — undergo a foaming chemical reaction — at high temperatures. In the construction industry, millimeter-thick intumescent coatings on steel girders protect a skyscraper’s skeleton. Grunlan’s group scaled the technology down to nanometer-thick alternating layers of the compounds, polysodium phosphate and poly-allylamine. 

When cotton fabric treated with 10 alternating layers of each chemical was exposed to a flame for 10 seconds, the fabric charred but didn’t burn up, Grunlan says. The only sign of damage was localized, minor charring where the flame touched the fabric. Li, Grunlan and colleagues published details of these experiments online July 29 in Advanced Materials.

These data “sound really good,” Wilkie says — if the concern is preventing ignition of flammable materials. But in the real world, fires last considerably longer than 10 seconds, he points out, so these materials might retard burning or limit its spread, but wouldn’t withstand an inferno.

Vince Baranauskas of NanoSonic Inc. in Pembroke, Va., a firm that engineers materials including fire retardants, cautions that nano-layered flame retardants may not be feasible on a commercial scale. “Alternating dips would cost a great deal more than the fabric itself,” he says.

But Serge Bourbigot of the University of Lille in Villeneuve d'Ascq, France, remains optimistic. The new nanolayer fire retardants — with or without intumescence — are novel and show great potential, he says, even if they might need refinements before they are marketed.

Found in: Environment, Molecules and Technology

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News in Brief: Body & Brain

One defense against diarrhea and early hints of diabetes in obese children in this week’s newsWeb edition : Wednesday, August 31st, 2011

Body’s diarrhea defense
The body has a biological mechanism tailor-made to fend off infections by Clostridium difficile, a bacterium responsible for many hospital-acquired diarrheal infections. Reporting online August 21 in Nature Medicine, researchers at Case Western Reserve University and colleagues from other institutions show that a compound called S-nitrosoglutathione can bind to toxins secreted by the microbe and neutralize them before they damage cells. Increased levels of S-nitrosoglutathione in the guts of mice protected them from C. difficile, the researchers report. —Nathan Seppa

Third graders en route to adult disease
Obese but apparently healthy children 7 to 9 years old were twice as likely to be insulin resistant (a hallmark of impending diabetes) as were normal weight children their age, a team of scientists from U.S. universities finds. The scientists compared a range of features characterizing the blood, vascular health and fat-processing in 123 children. A whole host of prediabetes and pre-heart disease changes were evident in the obese youngsters. These children also were beginning to store fat outside of normal sites, the researchers report online August 25 in Obesity. The results “highlight the importance of interventions to prevent and manage obesity” very early in life. —Janet Raloff

Found in: Body & Brain

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Obesity can turn body fat toxic

A lucky few escape the link with disease-causing inflammation, two studies findWeb edition : Friday, September 2nd, 2011

Obesity can trigger inflammation in the fat cells found just below the skin, creating an environment that has been linked with the development of both diabetes and heart disease, two new studies indicate.

The findings suggest that people need to worry about all types of body fat, not just the deeply embedded fat that earlier work had focused on. But the new work also hints that some face a higher risk than others.

In the body, most fat clusters under the skin in what’s known as subcutaneous adipose tissue. Much of the rest, called visceral fat, accumulates within muscle and between organs deeper inside the body. For more than a decade, studies have shown that obesity triggers visceral fat to begin spewing hormonelike chemicals called cytokines. These proinflammatory chemicals have been linked with metabolic syndrome, a constellation of abnormalities that can include impaired insulin sensitivity (known as insulin resistance), fat buildup around the waist, high blood pressure and low concentrations of HDL, the good cholesterol.

“There’s been this sort of ill-proven idea that subcutaneous adipose tissue is not harmful and that visceral adipose tissue is the vicious demon that makes us sick,” says Gökhan S. Hotamisligil of the Harvard School of Public Health in Boston, who was not involved in the studies. The new data, he says, reinforce the fact that subcutaneous fat is far from benign.

In one study, Ishwarlal Jialal of the University of California, Davis Medical Center in Sacramento and his colleagues sampled blood and subcutaneous fat from 65 men and women. Most were clinically overweight or obese, and 39 had metabolic syndrome.

Subcutaneous fat from people with metabolic syndrome was rife with macrophages, a type of immune molecule that normally kills unwanted cells. But here, Jialal says, macrophages “appeared to be conspiring with fat cells to produce a host of proinflammatory cytokines,” whose levels correlated with an individual’s insulin resistance.

This proinflammatory environment was absent in people without metabolic syndrome — even among people who were very obese, the researchers report in the November Journal of Clinical Endocrinology & Metabolism, in an article posted online August 24. Although obesity predisposes people to develop metabolic syndrome, concludes Jialal, it takes more than excess fat to trigger it.

A related trial, published in the July 12 Journal of the American College of Cardiology, probed inflammation and metabolic impairments associated with subcutaneous fat in 109 obese men and women and 17 lean individuals. Some had diabetes but none had known heart disease.

“We found no inflammation in the fat of lean individuals,” who also had healthy blood vessel function, notes cardiologist Noyan Gokce of Boston University School of Medicine. In contrast, roughly 70 percent of the obese people had metabolic syndrome or at least some abnormal metabolic parameters in blood tests. These people also showed evidence of inflammation-promoting fat and impaired blood vessel function.

But the big surprise, Gokce says, was that the other roughly 30 percent of the obese people had very little inflammation inside their fat, little evidence of insulin resistance and vascular function that was the same as in lean people. “So it seems that the quantity of fat may not be nearly as important as its quality.”

The new data “open up the idea that maybe we should revisit subcutaneous fat as a major player in the metabolic consequences of obesity,” says Alyssa Hasty of Vanderbilt University School of Medicine in Nashville.

Found in: Body & Brain

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News in Brief: Molecules

Tracking the source of wines’ deep reds, fish oil goes to the brain and more in this week’s news. Web edition : Sunday, September 4th, 2011

Red, red wine
Scientists can now tell whether a glass of deep red vino acquires its color from grapes or rice. Deep reds can attract a higher price and winemakers will sometimes blend wines with Rossissimo, a wine that’s extra rich in red pigment. In some markets pigments extracted from black rice are also used as “correctors,” but in Italy this practice is frowned upon. Reporting in the Sept. 9 Analytica Chimica Acta, Italian researchers report that high-end spectroscopic techniques can discern rice red from Rossissimo red. —Rachel Ehrenberg

Omega-3s down, suicide risk up
The heart-healthy omega-3 fatty acids found in fish oils might also help keep the head healthy. A new study finds that U.S. military personnel who were at high risk for suicide also had low levels of DHA, or docosahexaenoic acid, the major omega-3 used by the brain. The study does not establish cause and effect, but it adds to a growing body of evidence linking low levels of omega-3s with mood problems including depression. Researchers from the National Institutes of Health and the Uniformed Services University of the Health Sciences in Bethesda, Md., report the work online August 23 in the Journal of Clinical Psychiatry. —Rachel Ehrenberg

Wines’ notes
Descriptions of wine typically involve notes of fruit or musk, not piano or woodwind. But people do make associations between a wine’s scent and particular musical instruments, new research shows. When 30 study participants had to choose a sound to match a wine’s bouquet, five odors were consistently linked with particular instruments, scientists from the University of Oxford in England report in an upcoming Chemical Senses. Vanilla and apricot connoted woodwind and piano; blackberry also inspired primarily piano; and musky wines were linked to brass. —Rachel Ehrenberg

Found in: Molecules

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FOR KIDS: Possible new saltwater stains on Mars

Dark streaks that grow in spring, fade in winter may point to saltwater on the Red PlanetWeb edition : Wednesday, August 31st, 2011 This image of a slope inside a Martian crater is actually a combination of several pictures taken by an instrument onboard the Mars Reconnaissance Orbiter. Scientists suspect the long, thin dark streaks are signs of saltwater that flows and then evaporates.HiRISE, MRO, LPL (U. Arizona), NASA

Here on Earth, it’s easy to find saltwater: Just head to the nearest sea. Oceans cover most of Earth’s surface, which means if you were to transport yourself to a random spot on our planet, you would probably end up all wet.

Visit the new Science News for Kids website to read the full story: Possible new saltwater stains on Mars

Found in: Science News For Kids

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A lighter Higgs, but chase continues

Target narrows with new estimated mass for elusive particleWeb edition : Thursday, September 1st, 2011 An actual collision between two protons produces showers of particles whose paths and energies are recorded by the Large Hadron Collider’s CMS detector. This spray of electrons (thick red lines) and muons (thin red lines) looks similar to what would be expected from the Higgs, but could also be a background fluctuation.L. Taylor and T. McCauley/COPYRIGHT CERN 2011

In the hunt for the Higgs boson, the world’s most powerful particle collider has tightened the net. New data collected this year by CERN’s Large Hadron Collider near Geneva narrow the range of allowable masses for the hypothetical particle, whose existence would confirm the mechanism thought to give mass to other particles.

To fit with the standard model, the cornerstone of modern particle physics, the Higgs must now be lighter than 145 billion electron volts, or GeV. Team members from LHC’s ATLAS and CMS experiments presented their results August 22 in Mumbai, India at the International Symposium on Lepton Photon Interactions at High Energies.

This new limit goes beyond previous results from the Tevatron at the Fermi National Accelerator Laboratory in Batavia, Ill. — which directly excluded 156 to 177 GeV by looking for debris left behind when the Higgs breaks down, and indirectly ruled out masses above 185 GeV using theoretical calculations and measurements of other particles.

“We’ve now confirmed with direct searches that the mass of standard model Higgs, if it exists, is light,” says CERN’s Fabiola Gianotti, a spokeswoman for ATLAS.

Even as it runs out of room to hide, though, the Higgs is still playing hard to get. Faint hints of the Higgs that turned up at the LHC in July — particles with energies that could indicate a lighter Higgs — have only grown fainter in the new LHC data. No statistically significant signs of the Higgs have appeared in the rest of the remaining mass range.

A lighter Higgs is harder to find at the LHC. At lower energies, its signature tends to fade into the background. But CERN physicists still expect to discover or rule out the existence of such a particle in the next two years.

Found in: Atom & Cosmos and Matter & Energy

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