Tag: PNAS

Bees Not Bombs: Venom Protein Makes Fluorescing Explosive Detector

By Veronique Greenwood | May 10, 2011 3:24 pm

bees

What’s the News: The next generation of bomb detectors may come from an unusual source: bee venom, the stuff that hurts like all get-out when you get stung. A team of researchers at MIT have used fluorescent carbon nanotubes and venom proteins called bombolitins that bind to single molecules of explosives like TNT to create an exquisitely sensitive detector.

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CATEGORIZED UNDER: Living World, Technology

Hummingbirds Are Not Sipping Straws. They're Doing Something Much Weirder.

By Veronique Greenwood | May 4, 2011 9:43 am

What’s the News: Hummingbirds have been keeping a secret, now revealed by high-speed videos: their tongues are nothing like straws. They’re much more like mops.

Those dexterous helicopters of the sky (and mascots of this fine news aggregator) are known for consuming large quantities of flower nectar—as much as 14 times their body weight in a day—to power their speedy metabolisms (when your heart beats more than 1,200 times a minute, you’ve got to keep gobbling that fuel). Researchers had always thought that hummingbird tongues, which are forked, functioned like a coffee straw, with two slender tubes using capillary action—the force pulling liquid up the sides of a tube—to drink. But new video evidence shows the two halves of hummingbird tongues scooping up the fluid like tiny hands, knocking the straw theory out of the running.

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CATEGORIZED UNDER: Living World

Bacteria Survive & Reproduce in Gravity 400,000X Stronger Than Earth's

By Valerie Ross | April 27, 2011 11:49 am

e coliE. coli

What’s the News: Some bacteria can live in extreme “hypergravity,” found a new study published in the Proceedings of the National Academy of Sciences, surviving and reproducing in forces 400,000 times greater than what’s felt on Earth. These findings fit with the idea that microbes carried on meteorites or other debris—a ride that would have subjected them to hypergravity-strength forces—may be the ancestors of life on Earth.

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CATEGORIZED UNDER: Living World, Space

After a Nice Hot Blood Lunch, Mosquitoes Go Into Shock

By Veronique Greenwood | April 26, 2011 2:06 pm

skeeter

What’s the News: When mosquitoes finish a piping-hot meal of blood, they have more than your average postprandial snooze, biologists have found: they go into heat shock, producing proteins most organisms only make when something is terribly wrong.

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CATEGORIZED UNDER: Living World

Visual Virtual People: A Better Model for the Behavior of Crowds

By Veronique Greenwood | April 25, 2011 2:37 pm

crowds
A new model of crowd behavior uses simple visual rules.

What’s the News: When crowds go wrong, they go really wrong—more than 300 people died in a stampede in Cambodia last year during a festival, and hundreds more have been crushed to death in periodic disasters near the Muslim holy city of Mecca. A major flaw of computational models describing how people behave in crowds is that they are often too simplistic or too specific to a situation to explain both normal and disastrous behavior. A new model manages to recreate both types of behavior, working from two basic visual rules: (1) each person will move in the least crowded direction in their line of sight, and (2) they will adjust their speed to maintain a safe distance from visible obstacles.

“This work is an extremely important step in pulling together our fragmented understanding,” says behavioral biologist Iain Couzin, who was not involved in the study (via ScienceNOW). “We’re now approaching a sort of unified understanding of human behavior in crowds.”

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CATEGORIZED UNDER: Mind & Brain, Physics & Math

Ancient Stone Structures Herded Gazelles to Mass Slaughter

By Valerie Ross | April 20, 2011 9:44 am

What’s the News: Large, corral-like stone stone structures found in the Middle East, called desert kites, were used to capture entire herds of gazelle for slaughter 6,000 years ago, suggests a study published online yesterday by the Proceedings of the National Academy of Sciences. While historians and archaeologists have long suspected the structures may have been used to round up and kill gazelles, this study, which found and dated thousands of gazelle bones in close proximity to several desert kites, provides physical evidence to corroborate the idea and an estimate of when the kites were used. (A labeled aerial photo of a desert kite can be found here.)

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CATEGORIZED UNDER: Human Origins, Living World

Study: Ammonia-Packed Meteorites Could Have Provided Nitrogen for Early Life

By Andrew Moseman | March 1, 2011 11:57 am

One nitrogen atom, three hydrogen atoms. That’s all it takes to make the basic ammonia molecule. This simple compound was one of the most important building blocks for the origin of life, scientists believe, providing the nitrogen that is crucial to many organic compounds. They just don’t know for sure how so much of it could form under the conditions of the early Earth.

In a new study this week, Sandra Pizzarello and colleagues tie the ammonia surplus to one of the more fascinating theories about the rise of life—that some of its basic components seeded the Earth from space on board meteorites that pounded the planet’s surface.

Pizzarello’s team analyzed a particular meteorite found in Antarctica. Its name is Graves Nunataks (GRA) 95229, and it was discovered in 1995. But its important characteristic is that the it belongs to a class of meteorites called carbonaceous chondrites that are full of organic materials. In the lab, the researchers tried to simulate how those materials in GRA 95299 might have reacted when they reached the younger Earth.

Pizzarello and her co-authors subjected a sample of the meteorite … to temperatures of 300 degrees Celsius at high pressures in the presence of water to simulate hydrothermal conditions on the meteorite’s parent asteroid or on Earth. Under heat and pressure, GRA 95229 released almost nothing but ammonia, in amounts that constitute roughly 1 percent by mass of the type of meteoritic material examined. Its parent asteroid, the authors speculate, must have been rich in ammonia. [Scientific American]

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CATEGORIZED UNDER: Living World, Space

In Bird Flu-Swine Flu Hybrids, a Clue to What Makes a Super-Strain

By Andrew Moseman | February 28, 2011 5:45 pm

Swine flu is not gone, and it is not stagnant. Though the public health scare about the 2009 swine flu pandemic subsided, the virus—like avian flu—remains in pockets of animals, shuffling its genes while hidden from the watchful eyes of virus experts. Virologists call this genetic switcheroo “reassortment,” and it’s how new and dangerous strains of flu snuck up on humankind in the past—and how they could do it again. This time, though, virologist Jinhua Liu and colleagues are trying to get a jump on the viruses.

For a new study in the Proceedings of the National Academy of Sciences today, this team of Chinese researchers simulated what could be a dire situation for humans: swine flu (H1N1) and avian flu (H9N2) together in one animal. When these flu strains are together they can exchange genetic material. So to test what that mixing might produce, Liu’s team swapped genes between the two and created 127 hybrid viruses, testing each on mice.

Eight of these hybrid strains turned out to be more virulent and dangerous in the mice than their parent strains of swine flu and bird flu. [National Geographic]

According to Dutch virologist Ab Osterhaus, we can’t be sure that these eight nasty strains are the ones that would hit humans hardest—animal studies aren’t perfect.

“Mice mirror, to a certain extent, what happens in humans,” he says, but they are not perfect model animals. Liu agrees. He plans to investigate how contagious his new viral blends are in guinea pigs and ferrets—animals whose respiratory system better reflects our own feverish battle with flu. [ScienceNOW]

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CATEGORIZED UNDER: Health & Medicine

The Unkindest Cut: How Wounds Can Trigger Tumor Growth

By Patrick Morgan | February 15, 2011 11:05 am

Sometimes, even a tiny cut can have serious and unexpected consequences. New research reveals that even a minor flesh wound can cause previously dormant cancer cells to develop into tumors.

The study, published in the Proceedings of the National Academy of Sciences,  focuses on basal cell carcinoma, a variety of skin cancer associated with hair follicle cells. Basal cell carcinoma is the most common type of skin cancer, and while it rarely metastasizes or kills it’s still considered malignant.

Biochemists Sunny Wong and Jeremy Reiter, from the  University of California, San Francisco, wanted to see how tumors develop from cancerous mutations. To do that, they genetically modified mice so that their hair follicle stem cells expressed the human basal cell carcinoma gene. After giving some of the mice a small cut, and leaving others alone, they discovered that tumors only formed on the hurt mice.

When skin is cut, hair-follicle stem cells migrate to the injury. Wong says pre-cancerous cells can lie dormant in the body until a trigger, such as radiation or a build up of mutations, pushes them into forming a tumour. “In this case, wounding got cancerous cells out of their resting phase,” he says. [New Scientist]

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CATEGORIZED UNDER: Health & Medicine

Numbers Need Language to Make Sense in Our Minds

By Andrew Moseman | February 8, 2011 6:48 pm


How we talk about numbers plays a big role in how we think about numbers—that much is clear. But this week, new research makes the case that language is not a key part of thinking about numbers, but the key part, overriding other influences like cultural ones.

The study in the Proceedings of the National Academy of Sciences by psychologist Elizabet Spaepen focuses on a group of deaf Nicaraguans called the homesigners, who invented their own form of sign language—a form that lacks a numerical vocabulary.

That’s a common trait in many hunter-gatherer societies, where the numbering system is often one-two-three-many. For example, the Munduruku Amazonian people in rural Brazil don’t have any words for exact numbers larger than five. Their neighbors, the Piraha, no exact number words at all. [USA Today]

There are two things that make the homesigners extremely scientifically interesting. One is the fact that they spontaneously invented this language when brought together at a home for the deaf in the 1970s. And the other—the one that’s important for this study—is that they’re not an isolated tribe in which nobody uses numbers. They live within Nicaragua, surrounding by a Spanish-speaking society that’s as number-dependent as any other country. Thus, Spaepen’s team reasoned, if the homesigners struggle to conceptualize larger numbers, the reason would have to be linguistic and not cultural.

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CATEGORIZED UNDER: Mind & Brain
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