Saturday, 5 February 2011

Johnald's Fantastical Daily Link Splurge

Johnald's Fantastical Daily Link Splurge

Tiny Water Flea Has More Genes Than You Do

Posted: 04 Feb 2011 02:29 PM PST

By Mark Brown, Wired UK

This tiny, near-microscopic water flea has more genes than you. In fact, this freshwater zooplankton is the first crustacean to have its genome sequenced, and its 31,000 genes crowns it the animal with the most genes so far. For those keeping count at home, the average human has about 20,000 to 25,000 genes.

The translucent water flea is a Daphnia pulex, and lives in ponds and lakes throughout North America, Europe and Australia. It can also reproduce without sex, is the most commonly found species of water flea and is a "model organism", meaning it's studied extensively and provides insight into other, rarer species.

The reason for this little critters' super-high gene count comes down to its rapid rate of gene multiplication. "We estimate a rate that is three times greater than those of other invertebrates and 30 percent greater than that of humans," project leader and CGB genomics director John Colbourne said in a press release.

 

As well as having a massive number of genes, more than a third of them have never been seen before in other animals. "In other words, they are completely new to science," says Don Gilbert, coauthor and Department of Biology scientist at IU Bloomington. Those previously unknown genes are due to the nature of the flea's environment.

Doing genomic research on animals, even as tiny as this zooplankton, holds importance for humans too. "The Daphnia system is an exquisite aquatic sensor, a potential high-tech and modern version of the mineshaft canary," James E. Klaunig of Indiana University said in a press release. By looking at how changing environmental agents affect the celluar and molecular processes of this flea, we can extrapolate that to the genes shared in humans.

The findings were reported in the journal Science, by members of the Center for Genomics and Bioinformatics (CGB) at Indiana University Bloomington and the U.S. Department of Energy's Joint Genome Institute.

Image: Daphnia pulex, commonly known as the water flea./Jan Michels, Christian-Albrechts-Universitaet zu Kiel.

Source: Wired.co.uk.

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Video: Uncontacted Tribe in Brazilian Jungle

Posted: 04 Feb 2011 01:54 PM PST


Video of an uncontacted tribe spotted in the Brazilian jungle has been released, bringing them to life in ways that photographs alone cannot.

The tribe, believed to be Panoa Indians, have been monitored from a distance by Brazil's National Indian Foundation, a government agency charged with handling the nation's indigenous communities. Many of the world's 100 or so uncontacted tribes live in the Amazon.

Until 1987, it was government policy to contact such people. But contact is fraught with problems, especially disease; people who have stayed isolated from the mainstream world have stayed isolated from its pathogens, and have little immunity to our diseases. Brazilian government policy is now to watch from afar, and — at least in principle — to protect uncontacted tribes from intrusion.

Unfortunately, uncontacted tribes usually live in resource-rich areas threatened by logging, mining and other development. There's often pressure on governments to turn a blind eye. Videos like this, released by tribal advocacy group Survival International and produced by the BBC's Human Planet program, are legal proof that uncontacted tribes still exist, and deserve protection.

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Black Widow Spiders Are Wasteful Gluttons

Posted: 04 Feb 2011 12:00 PM PST

The most venomous spider in North America, the black widow, is actually a bit of a couch potato.

"They're sort of like humans, when they're around a lot of food they become lazy and wasteful," said J. Chadwick Johnson, a biologist at Arizona State University. "They'll kill food they don't need, and leave some of it uneaten."

Johnson's team describes the spiders' habits in a paper called "Wasteful Killing in Urban Black Widows: Gluttony in Response to Food Abundance," published online Jan. 17 in the journal Ethology. Wastefulness is strange to see in animals, because hunting involves spending energy, risking injury and killing prey that might be needed later.

Other research from Johnson's lab has shown that black widows can inherit some feeding tendencies, such as a taste for cannibalism, from their parents. For this study, they wanted to see if wasteful killing was a product of a spider's individual traits, or if most black widows — which, when they're not being wasteful, can go two months without eating — behave the same way.

 

In the lab they fed crickets to spiders, then measured how much the spiders ate. Some of the spiders hadn't eaten in two days; others had gone without food for 7 or 14 days. Johnson's team found that the spiders were quicker to attack and ate more food when they'd gone longest without eating. Habits in individual spiders, which would suggest a genetic component of gluttony, didn't show a trend.

"The spiders are more aggressive when they're hungrier," Johnson said. "The simplest explanation is that."

It isn't clear if this kind of feeding is adaptive for the spider, but it might be a way of attracting mates. Other studies show that male black widow spiders are attracted to the smell of well-fed females.

"Even if she's not around her web, he'll get turned on and begin courting like crazy," Johnson said.

If a male black widow chooses to mate with a starving female, he risks becoming a post-nuptial snack. Johnson speculates that females might be advertising for males by leaving wasted food in their web.

It sends a signal: "Come hither, because I won't kill you."

Image: Female black widow spider, Latrodectus mactans. (James Gathany)

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Citations: "Wasteful Killing in Urban Black Widows: Gluttony in Response to Food Abundance." By Patricia Trubl, Valerie Blackmore and J. Chadwick Johnson. Ethology, Vol. 117, Issue 3, March 2011.

Small Asteroid Passes Close to Earth Today

Posted: 04 Feb 2011 10:56 AM PST

A small asteroid swooped within 7,366 miles of Earth on Feb. 4 — today — at 2:40 p.m. EST [19:40 UT].

The object, called 2011 CQ1, was discovered earlier today by astronomer Richard Kowalski using a 0.68-meter telescope near Mount Bigelow outside of Tuscon, Arizona as part of the Catalina Sky Survey's routine scanning of the skies for small objects that come close to Earth.

2011 CQ1 is tiny by asteroid standards, only about 6.5 to 10 feet across. But though it is small, it will be close. The last asteroid to come within moon-distance to Earth, 2010 TD54, stayed a chaste 27,960 miles away at its closest approach Oct. 12 — more than three times the distance to 2011 CQ1.

 

The asteroid is not on a collision course with Earth, but it will come well within the so-called Clarke Belt where satellites in geosynchronous orbit hang out.

Although the daytime skies are too bright to see the new object in the US, 2011 CQ1 will be visible for a few hours in dark skies, according to Ernesto Guido and Giovanni Sostero of Remanzacco Observatory in Italy. If you're under those dark skies and catch a photo of this new object, send us your best shots.

Via Spaceweather.com

Image: G. Sostero and E. Guido

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Your Next Football Party Could Be Vacuum Fried

Posted: 04 Feb 2011 10:00 AM PST

Championship games come and go, but one Super Bowl matchup remains the same: yummy, unhealthy fried snacks versus healthy, unyummy vegetables.

Perhaps that will change. Food engineers at Chile's Pontificia Universidad Catolica say they've developed a new way to use vacuum fryers to make lower fat, more nutritious snacks, without sacrificing taste.

"People want healthier food, but it is really difficult to change habits," said civil engineer Pedro Bouchon, co-author of the paper published Jan. 19 in the Journal of Food Science. Bouchon says his technique for vacuum-frying carrot and potato chips absorbs 50 percent less oil than traditional methods. For fried apples, he can reduce oil by 25 percent.

Food becomes fried – that is, brown, crunchy and delicious – when put in oil so hot that water inside the food evaporates. The hotter the oil, the more is absorbed. Putting the process in a vacuum lowers water's evaporation point. Food can fry at lower temperatures, absorbing less oil.

Pictures of carrot, potato and apple slices fried at increasing temperatures. Raw slices on the right. Image: Journal of Food Science

Vacuum frying is popular in Asia for fruit and seaweed snacks, but isn't yet popular in the United States. Different techniques are needed for different fruits and vegetables, so Asian techniques aren't directly applicable to U.S. tastes.

Bouchon's study is among the first to search for vacuum frying's sweet spot in western snack foods.

He fried carrots, potato chips and apples at different combinations of pressure and temperature, searching for the range that minimized fat, maximized flavor and kept nutrients intact.

Bouchon's fried potatoes and apples keep 95 percent of their vitamin C, compared to 50 percent retained by conventional frying. His fried carrots and potatoes absorbed about 50 percent less oil than atmospheric-fried chips, his apples about 25 percent less. Vacuum frying also reduces the amount of acrylamide in a potato chip, a suspected carcinogen found in starchy fried food.

Bouchon measured flavor with a chemical analysis that tests for so-called Maillard reactions, which produce "browning" in food. (He verified those results by letting his children taste the snacks.)

One non-dietary factor slowing the adoption of vacuum frying in the west has been expense. At the moment, vacuum fryers are more expensive to install and operate than standard frying devices, and are considered financially risky.

However, Bouchon believes that, given public demand for healthier snack food, companies will soon turn to vacuum frying.

"This is absolutely in line with what the public wants," he said.

Images: 1) Flickr/Philosophographlux. 2) Journal of Food Science.

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Solar-Sail Flare Visible From Earth

Posted: 04 Feb 2011 08:28 AM PST

The first Earth-orbiting solar sail has been caught streaking across the sky. When glints of sunlight reflect off NASA's NanoSail-D satellite, the 10-square-meter sheet of shiny space-age material can briefly outshine the brightest stars.

NanoSail-D unexpectedly unfurled on Jan. 20, after spending a month trapped in its mothership. It is the second solar sail to ever be successfully deployed, and the first to orbit the Earth.

Between now and April or May, the shimmering sheet will skim through the upper atmosphere, slowly descending as it accumulates drag. The idea is to test potential "drag sails" that could help automatically remove future satellites from orbit at the end of their lives, reducing space junk.

Until then, watch the skies. As NanoSail-D sinks closer to Earth, it could flash ten to 100 times brighter than the planet Venus. That's the sort of thing you can see even through city lights.

These flares may be a challenge to spot, though, because of the unpredictable viewing geometry. When viewed edge-on, it's invisible. The sail only glints when the angle with the sun is right. Several websites, including Heavens-Above, Spaceweather.com and Calsky, can tell when NanoSail-D will be overhead, but not when it will flare.

Later in the mission, the best bet for catching a flare is when the sail is near the horizon. Right now the sail is tumbling, so flashes could occur at any time. But as it drags through the atmosphere, it will flatten out, with the flat surface facing forward like an ocean-faring ship. That means it will be edge-on when it's high in the sky, but face-on and likely to flash closer to the horizon.

The beautiful photo above was captured Jan. 30 by Finnish astrophotographer Vesa Vauhkonen. If you can take a better one, submit it to NASA. NASA and Spaceweather.com are sponsoring a contest for the best images of NanoSail-D submitted between now and when the sail disintegrates. You could even win some cash. So look up!

Image: Vesa Vauhkonen/Spaceweather.com

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Universe’s First Stars May Still Shine

Posted: 04 Feb 2011 07:11 AM PST

Talk about glimmers from the past. Some of the universe's first stars may still be shining in the Milky Way 13.4 billion years after they formed, new simulations suggest.

The study, reported online Feb. 3 in Science and posted at arXiv.org on January 28, contradicts the prevailing view that the first stars were all behemoths that burned brightly and died out in a few million years.

In their simulations, Paul Clark of the University of Heidelberg in Germany and his colleagues showed that gas clouds in the early universe could have forged several stellar embryos rather than just one. Clark, along with Thomas Greif of the Max Planck Institute for Astrophysics in Garching, Germany, and other collaborators confirm that finding in an article posted at arXiv.org on January 31.

The infant stars in each cloud were closely spaced, and the team suggests that their mutual gravity could kick the lowest-mass embryo from the tightly packed group — before that infant has had a chance to grow into a massive, short-lived star.

A few of these ejected, underweight stars could have survived to the present day, if they managed to accumulate no more than the equivalent of 80 percent of the sun's mass from their birth cloud, Clark says.

 

Other researchers say they have several qualms about those conclusions. "This is an interesting and tantalizing result, but it is not based on computational physics but rather an ad hoc assumption" about the evolution of disks that surrounded the birth clouds of the first stars, contends Michael Norman of the University of California, San Diego. After reviewing a companion paper submitted by the same research team to Nature, Norman says he advised the journal not to publish it.

Although Clark and his coworkers simulated a longer period of the formation of the first stars than other teams have — the first 100 to 1,000 years of a process that lasts for several hundred thousand — it's still not long enough to determine the final weight of the primordial stars, says Tom Abel of the SLAC National Accelerator Laboratory in Menlo Park, Calif. The simulation technique used by the researchers in their Science paper is not as mathematically rigorous as other methods, even though it can probe the star formation process for longer, he adds.

If any of the first stars did survive until today, their brightness wouldn't require an exceptionally large telescope to image them, says Simon White of the Max Planck Institute for Astrophysics, a coauthor of the arXiv paper. But making a positive ID won't be easy, he adds. Only high-resolution spectra could distinguish primordial stars, which would contain only hydrogen and helium, from slightly younger stars containing trace amounts of heavier elements, he notes.

And in a case of hiding in plain sight, astronomers would still need to develop a strategy for determining which of the hundreds of millions of glittering stars at the center of the Milky Way are most likely to be primordial, says White.

Images: Courtesy of University of Heidelberg/UT Austin/Texas Advanced Computing Center. 1) The birth of a primordial star (blue dot, center) in a supercomputer simulation. In the spiral pattern forming around the star, some perturbations are large enough to trigger the formation of other stars (red spot, left). 2) A computer simulation shows the birth of some of the universe's first stars, some of which may still exist today. As star embryos form over time (white crosses), the mutual gravity of the densely packed infants may have ejected the lowest-mass member before it had a chance to grow into a massive, short-lived star.

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Posted by johnald