Friday 11 February 2011

Johnald's Fantastical Daily Link Splurge

Johnald's Fantastical Daily Link Splurge

Thousands of New Stars Emerge in Glowing Nebula

Posted: 10 Feb 2011 01:30 PM PST

Thousands of young stars come to the fore in in this beautiful new image from the Spitzer Space Telescope.

The previously unseen stars were born around 1,800 light-years from Earth in a region called the North American Nebula. In images that capture the same range of light that human eyes can see, the nebula looks like the eastern seaboard of the United States, down to the Gulf of Mexico. But most of that light is reflected off clouds of dust that hide infant stars. Only about 200 young stars were known before.

This image breaks through the clouds to find more than 2,000 new objects that may be young stars. (More data processing will determine their nature.) Because Spitzer is sensitive to infrared wavelengths that can sense heat, it can see the glow of the dusty, buried stars.

"One of the things that makes me so excited about this image is how different it is from the visible image, and how much more we can see in the infrared than in the visible," said Spitzer astronomer Luisa Rebull in a press release. "The Spitzer image reveals a wealth of detail about the dust and the young stars here." A paper detailing the observations has been accepted in the Astrophysical Journal Supplement Series.

Stars are born inside collapsing balls of gas and dust, which flattens into a disk that spins together with the star like a record album. As the star ages, the disk is thought to congeal into planets. Most of the dust is expected to dissipate by the time the star is at the center of a mature solar system.

The new Spitzer image shows stars in all stages of development, from dust-blanketed infancy to early adulthood, when stars are new parents to a growing family of planets.

Despite the new views of its growing stellar family, the North American nebula is still shrouded in mystery. The group of massive stars that is thought to dominate the nebula is still unseen. The Spitzer image and images from other telescopes hint that the missing stars lurk behind the Gulf of Mexico portion of the nebula.

In this image, infrared light with a wavelength of 3.6 microns is colored blue; 8.0-micron light is green; and 24-micron light is red. Since taking this image, Spitzer ran out of the coolant needed to keep the two longest wavelength detectors working. Spitzer is still snapping photos in the two shorter wavelength bands.

Images: 1. NASA/JPL-Caltech 2. L. Rebull/SCC/Caltech

See Also:

Lucy’s Feet Were Arched and Stiff, Just Like Ours

Posted: 10 Feb 2011 12:00 PM PST

How did Lucy walk? Although the famous 3.2-million-year-old skeleton shows that she was undoubtedly an upright walker, our incomplete knowledge of her feet has fed a long-running debate about the mechanics of her stride. Now, thanks to the discovery of a single bone, scientists have found important similarities between Lucy's feet and our own.

Reported Feb. 10 in the journal Science by University of Missouri anthropologist Carol Ward and co-authors William Kimbel and Donald Johanson of Arizona State University, the single foot bone was discovered in 2000 and comes from Hadar, Ethiopia. Of the same age as Lucy herself, this site contains the remains of many Australopithecus afarensis individuals who died under mysterious circumstances.

The bone is a fourth metatarsal; one of the bones of the mid-foot, just behind the toes. In modern humans, metatarsals create the distinctive arch of the foot and act as a shock absorber while keeping the foot stiff. Earlier research has shown, however, that the degree of the arch has varied during human history.

 

Like the same bone in our foot, but unlike that seen in chimpanzees or gorillas, the fourth metatarsal of this A. afarensis individual angled down to contact the ground, creating a strong, weight-bearing arch along the outside edge of the foot. Also telling were two facets on the bone's end where it connected with the rest of the foot, trading the flexibility seen in ape feet for strength and stability.

This discovery may also resolve a long-running debate over the identity of prehistoric humans who left 3.6-million-year-old tracks in an ash bed found at Laetoli, Tanzania. The only human fossils found that locality are A. afarensis, but paleoanthropologists have disagreed about whether Lucy's relatives truly could have left the tracks due to supposed differences in skeletal anatomy. As Ward and colleagues argue, the confirmation of an arched foot in A. afarensis removes this objection, meaning they were probably the true track makers, after all.

Despite the newfound correspondences between the A. afarensis foot and our own, their feet were significantly different from ours. According to American Museum of Natural History paleoanthropologist William Harcourt-Smith, who was not involved in the Science study, "If you look at the A. afarensis foot as a whole, it has a combination of human-like and ape-like features." Much like the rest of their skeletons, the anatomy of these hominids' feet is a mosaic of features seen in earlier and later humans. Some features of our own skeletons – such as the arch on the inner side of our foot – are not seen in A. afarensis.

The description of the metatarsal bone will inform paleoanthropologists about the way Lucy moved, but just how she walked and how that fits into the bigger picture of human evolution requires further study. "A. afarensis was a biped," says Harcourt-Smith, "but not one like us."

Image: The A. afarensis fourth metatarsal, and its analogue in the bones of a human foot. (Kimberly Congdon, Carol Ward and Elizabeth Harman)

See Also:

Citation: "Complete Fourth Metatarsal and Arches in the Foot of Australopithecus afarensis." By C.V. Ward, W.H. Kimbel and D.C. Johanson. Science, Vol. 331 No. 6018, Feb. 11, 2011.

Male Squids ‘Kick Ass’ at Touch of Female Pheromone

Posted: 10 Feb 2011 10:01 AM PST

Just a touch of a female pheromone can send male longfin squids into a frenzied rage, potentially giving wimpy squid males a chance to fight for the ladies.

Whether there exists a human analogue to the pheromone, called Loligo beta-microseminoprotein, is a matter of premature speculation. But the findings do reveal a potentially fascinating subject for further research.

"It's like Popeye's spinach. When they touch it, they say 'let's go' and start to kick ass," said biologist Roger Hanlon of the Marine Biological Laboratory, who reported the findings Feb. 10 in Current Biology. "It's a beautiful, robust response. It may be a mechanism for smaller males who have trouble being dominant to mate with females."

Pheromones are compounds produced by animals that trigger behaviors and physiological cycles in their brethren, including aggression, alarm, ovulation and even sex. As their mating season peaks in the spring, female longfin squids secrete Loligo beta-microseminoprotein onto their capsules of eggs.

During a 1997 dive to investigate the longfin squid's mating behavior, Hanlon and others placed one female egg capsule in a school of about 1,000 squids. All of a sudden, the males — which typically show no signs of aggression — went crazy.

"Males are visually attracted to egg capsules. So one bold male squid wiggled his arms in there and immediately started fighting with other males," Hanlon said. "Another came down and started fighting, then another, then another." Within five minutes, the entire school had spawned.

Hanlon and his team went on to search for compounds that could trigger the behavior. They brought wild squids into the lab, then isolated compounds secreted by female genitals and in eggs. Males were exposed to each compound until the researchers found one that drove them nuts: Loligo beta-microseminoprotein (video below).

The pheromone resembles a class of poorly understood compounds secreted in reproductive cells and fluids across the animal kingdom, including mammals. However, Hanlon cautioned against thinking it would have an effect on people.

"It's easy to take a molecule that turns on aggression in squid out of context, though. The NFL and Army shouldn't be calling for this stuff. It's so far removed from that," he said. "There is no evidence at all that it would cause aggression in any vertebrate animal, let alone humans."

Neurobiologist Edward Kravitz of Harvard University, who studies aggression in flies, called the finding compelling and is curious to see where it leads.

"People think these may be signaling molecules. It's possible this is a molecule used throughout evolutionary history for a similar purpose," Kravitz said.

Many other questions remain about the pheromone's function in squids.

"We don't know how it gets into the suckers and the blood stream, what receptors it affects, and how it influences the nervous system," Hanlon said. "This is really just the beginning, and we hope to inspire other folks to start looking closely at how this class of proteins function."

Images: Longfin squids, also known as Loligo pealei (WHOI/Tom Kleindinst)

Video: Roger T. Hanlon/The Marine Biological Laboratory.

Citation: "Extreme Aggression in Male Squid Induced by a β-MSP-like Pheromone." Scott F. Cummins, Jean G. Boal, Kendra C. Buresch, Chitraporn Kuanpradit, Prasert Sobhon, Johanna B. Holm, Bernard M. Degnan, Gregg T. Nagle, and Roger T. Hanlon. Current Biology, Feb. 22, 2011. DOI: 10.1016/j.cub.2011.01.038

See Also:

Rogue Planets Could Harbor Life

Posted: 10 Feb 2011 08:42 AM PST

If a planet is ripped from the warm cradle of its solar system and plunged into the frigid depths of space, it could still hold on to a liquid ocean — and maybe life — beneath an icy crust.

Planet formation models suggest that small planets are regularly flung from their solar systems by close encounters with neighboring gas giants. The giants' gravitational fields create an interplanetary slingshot effect, sending smaller planets on unstable orbits that quickly leave their star behind.

Prior to ejection, some of those planets could conceivably be like Earth, with continents, oceans and biospheres. A new model suggests that submarine aliens on such a planet could have a chance at survival.

"We originally started with the question, 'What if you turned off the sun?'" said University of Chicago geophysicist Dorian Abbot, co-author of a paper submitted to Astrophysical Journal Letters and prepublished Feb. 5 on arXiv.org.

Along with fellow University of Chicago astrophysicist Eric Switzer, Abbot ran the numbers to see if an ocean could stay liquid without heat from a star. They called their rogue world a Steppenwolf planet, "since any life in this strange habitat would exist like a lone wolf wandering the galactic steppe."

 

The pair assumed the planet was between 0.1 and 10 times Earth's mass, with a similar amount of water and rock. Once the planet was flung its warm, nurturing star, the ocean would start to freeze. But leftover heat from the planet's formation and decaying radioactive elements in the rock could keep the ocean warm beneath a shell of ice. As long as the planet could keep the ice from freezing all the way to the core, the ocean should be safe.

Abbot and Switzer calculated that a planet 3.5 times the mass of Earth would be warm enough at the core to maintain a liquid ocean beneath an ice crust a few kilometers thick. The ocean could last for about 5 billion years.

"That's a non-ridiculously short timescale," said astrobiologist Cynthia Phillips of the SETI Institute, who was not involved in the new work. "It seems like this thick ocean could actually persist for longer than you might assume, without going through the numbers."

Phillips studies the possibility of life beneath the icy crust of Jupiter's moon Europa, a world superficially similar to the hypothetical Steppenwolf planet. But unlike the rogue world, most of Europa's heat comes from tides raised by Jupiter.

In a slightly more bizarre twist, Switzer and Abbot imagined the Steppenwolf planet with volcanoes spewing carbon dioxide into the atmosphere. The gas would freeze and fall as snow almost immediately, covering the world with an insulating blanket of dry ice. In that case, planets as small as 0.3 times the mass of Earth could keep a liquid ocean.

"That, I'm a bit more dubious about," Phillips said. With only decaying radioactive elements providing heat, "it seems unlikely that you'd have serious volcanic activity going on, without any other energy present."

Life on the planet could consist not only of organisms that survived the interstellar turmoil and adapted, but those that evolved later, around hydrothermal vents at ocean floors.

Abbot and Switzer declined to speculate what such life would look like, but they and Phillips agreed that it would almost certainly be microscopic.

"I would be very, very surprised if a planet like this could sustain big macroscopic life forms, just because the energy is so limited," Phillips said.

If these inhabited, free-floating planets exist, they could have been a vehicle for bringing the seeds of life to Earth. If the planet came within about 0.01 light-years of Earth, it could even be observed from the ground, Abbot and Switzer suggested.

But the odds of that happening about one in a billion at best, Switzer said. The researchers mostly meant to muse on the extreme possibilities for habitable worlds.

"If you can imagine life on such an object," Abbot said, "potentially there could be life in many sorts of weird situations that we haven't thought of before."

Image: Jupiter's moon Europa, which could harbor life in a liquid ocean beneath an icy crust. (NASA)

See Also:

"The Steppenwolf: A Proposal for a Habitable Planet in Interstellar Space." Dorian S. Abbot and Eric R. Switzer. arXiv.org, Feb. 5, 2011.

Fleas Jump Using Spring-Loaded Feet

Posted: 10 Feb 2011 07:14 AM PST

A decades-old debate about how the animal kingdom's most renowned jumper jumps appears to be settled.

No, not rabbits or frogs. Fleas.

Using new tools like high-speed video, researchers with the University of Cambridge in England have shown that fleas take off from their tibia and tarsi — the insect equivalent of feet — and not their trochantera, or knees. The researchers report their conclusion in the March 1 Journal of Experimental Biology.

Regardless of how fleas do it, the insects have always been famous jumpers, says study co-author Gregory Sutton. "There are even fairy tales that talk about how magnificent fleas are at jumping," he says. And it's not surprising: Fleas jump far. Some fleas — only a few millimeters long — can jump well over 10 centimeters, according to one study. Adult hedgehog fleas (Archaeopsyllus erinacei) go from resting to midair in about 1 millisecond, says Sutton, a mechanical engineer at Cambridge.

 

No known muscle can generate anywhere near the power needed to launch a flea so far, Sutton says. In the late 1960s, researchers discovered that the bugs aren't jumping with just their muscles. Instead, they spring. Before fleas launch, they store energy in a naturally springy protein hidden away in their bodies called resilin, then release it in one big bound.

But where the spring power goes from there wasn't clear. One camp said the force moves down to the knees, the other said the feet. "They argued about it," Sutton says, and for years the technology didn't exist to put the matter to rest.

It did, however, for Sutton and biologist Malcolm Burrows. With a little "flea wrangling," the researchers were able to collect 51 slo-mo clips of leaping hedgehog fleas.

The St. Tiggywinkles Wildlife Hospital Trust in Buckinghamshire, England, donated the fleas right off the backs of hedgehogs, the researchers note. The team also drew up mathematical models to simulate bug leaps on paper and eyed flea anatomy up-close using a scanning electron microscope.

Each avenue of exploration came up feet. For starters, flea knees never even touched the ground in about 10 percent of the jumps, Suttonsays. With or without knee contact, the fleas still jumped with the same speed and acceleration.

The team also found long spikes on the flea tibia and tarsi — good for traction, perhaps — but only short hairs on the knees. The jumps Sutton and Burrows watched on film also matched the predictions in their feet-jumping but not knee-jumping mathematical models.

"It seems like a pretty good nail in the coffin," says Dan Dudek, who studies biomechanics at Virginia Tech in Blacksburg. But studies like these are more than just flea circuses, he says.

Faced with the limitations of human manufacturing, many biologists and engineers have turned to living organisms for inspiration. Dudek studies the resilin protein, which he says is more resilient than any man-made spring.

"Certain animals are interesting and worth studying in their own right," he says. "But understanding that force generation, translation and control may make it easier to understand a jumping robot."

Sheila Patek, a biologist at the University of Massachusetts Amherst, agrees. But, she says, many organisms — from spore-shooting fungi to stinger-shooting jellies — have independently evolved fast and furious traits. Engineers have the option of copying not just one animal, but picking and choosing among the best of the entire evolutionary spectrum, she says.

And humans may have barely touched on what animals can do, Sutton says. The legendary abilities of jumping fleas, too, may be just that — a fairy tale.

Both locusts and bugs called froghoppers jump faster and with wider ranges than the itchy flea, he says. "Given how many insect species there are," he says. "I find it hard to believe that the fastest insect lives in the front garden."

Image: Flea under a scanning electron microscope. (CDC/Janice Haney Carr)

See Also:

Gibbons Sing With Regional Accents

Posted: 09 Feb 2011 02:54 PM PST

By Liat Clark, Wired UK

Regional accents have been discovered in the songs of crested gibbons, our closest relatives after great apes.

The small apes (genus Nomascus) — found in Vietnam, Laos, Cambodia and southern China — were already known to communicate in species-specific song when defining territory or attracting mates. However, researchers from the German Primate Centre in Göttingen have discovered conclusive correlations between song structure, genetics and geography, answering questions surrounding the primates' evolutionary development and migration patterns in the process.

Evolutionary biologist Van Ngoc Thinh explained in a press release: "Each gibbon has its own variable song but, much like people, there is a regional similarity between gibbons within the same location."

 

The study, published yesterday in the BMC Evolutionary Biology journal, focused on the song structure of six crested-gibbon species, paying particular attention to the four most closely related. More than 400 male and female songs were recorded from 92 groups, in 24 different locations.

"The structure of gibbon songs shows a clear adaptation to improved long-distance transmission," the study states, meaning they have adapted to their natural habitats in forests across Asia. Songs are emitted in single-frequency bands with slow modulation, producing a sound more akin to that of rain-forest birds than to other primates.

Though there are similarities in species' song structures, there are many variations — as with individual voices. By comparing analysis of 53 different vocal features with species' genetics, it was found that four of the most similar songs came from species with the most closely related DNA and the closest proximity to one another. It was also discovered that gibbons from the southernmost regions were more closely related than those in northern Vietnam and China, indicating the primates originated in the north and popular migration is to the south.

It was concluded that songs and calls of other primate species are likely to proffer similar results, therefore these findings can be more widely used to help researchers identify genetic relationships between species and define migration history.

Image: Black-crested gibbon./Flickr/Stephen Desroches.

Source: Wired.co.uk.

See Also:

Animal Kingdom Gains Phylum But Loses Link

Posted: 09 Feb 2011 12:57 PM PST

A new rearrangement of the animal kingdom has expanded a little-known offshoot into a major branch, and opened a gap between relatively simple and highly complex life.

Ocean-dwelling flatworms called acoelomorphs were thought to represent one of life's early stages, bridging primitive animals with radially symmetrical bodies, like jellyfish and sea anemones, and animals with bilaterally symmetrical bodies, from butterflies to humans.

But acoelomorphs now appear related to Xenoturbella, a bilaterally symmetrical ocean worm.

"It was nice to have this intermediate group between jellyfish and the other complicated animals. We've lost that," said Max Telford, a University College London geneticist and co-author of the new analysis, published Feb. 9 in Nature.

 

The identity of both worms is a matter of ongoing interpretation among scientists who map life's tree. Until the early 1990s, both were lumped with the Platyhelmine, or "true flatworm," phylum. Then genetic data reclassified Xenoturbella as molluscs and acoelomorphs as descended from that unknown, ur–complex animal.

Over the last decade, the Xenoturbella interpretation was revealed as a mistake. It wasn't a mollusk, but ate them: Researchers had confused DNA from shellfish prey with genes from Xenoturbella itself. Thus corrected, Xenoturbella was recognized as a phylum unto itself, clearly grouped with other bilaterally symmetrical animals.

Now Telford's team has turned a corrective lens on the acoelomorphs. Like other phylogenists, the team analyzed DNA from species in every phylum, searching for patterns of relationships and then constructing a tree to fit the data. But Telford and fellow researchers made one key adjustment, tweaking their algorithms to account for the unusually high mutation rates of acoelomorphs.

"They've evolved much more quickly than other animals," said Telford. "We suspected that this effect caused previous studies to put them a long way from animals with normal rates of evolution."

This rate-adjusted analysis pulled the acoelomorphs out from the base of the tree of life, and set them down on a far branch alongside Xenoturbella. Together, the two Xenoturbella species and hundreds of acoelomorph species constitute a newly classified phylum, which the researchers named Xenacoelomorpha.

Xenacoelomorpha is on roughly the same branch of life's tree as sea stars, sea cucumbers and acorn worms — not the most complicated animals, but far more complex than what the acoelomorphs were thought to be.

As for what might replace acoelomorphs as a candidate for root-animal status, Telford doesn't know.

Another question raised by the findings is how and why acoelomorphs evolved in such fashion. Their ancestors were likely creatures with guts, fluid-filled cavities and gill slits. Acoelomorphs have none of these features, and are so physically primitive as to resemble researchers' notions of how an ancient animal ought to appear.

"Now we've got these very simple worms nested right in the middle of the complex animals," said Telford. "How did they end up so simple? They must have lost a lot of complexity."

Videos: 1) Acoelomorph flatworm/Max Telford. 2) Xenoturbella/Max Telford.

See Also:

Citation: "Acoelomorph Flatworms Are Deuterostomes Related to Xenoturbella." By Herve Philippe, Henner Brinkmann, Richard R. Copley, Leonid L. Moroz, Hiroaki Nakano, Albert J. Poustka, Andreas Wallberg, Kevin J. Peterson & Maximilian J. Telford. Nature, Vol. 470 No. 7333, Feb. 9, 2011.
Posted by johnald