- Leaves Show Looped Networks May Be Better Than Branched
- Best View Yet of Pluto Shows Rapidly Changing Surface
- Dinosaur Fossil Reveals True Feather Colors
- Compare Aerial Images of WWII Destruction With Today in Google Earth
- Athletes Beware, Scientists Hot on Gene Doping Trail
- Gene Patents Under Legal Attack
- Altitude Causes Weight Loss Without Exercise
Posted: 04 Feb 2010 08:21 PM PST
Tree branches have inspired efficient transit networks, but a new study finds inspiration in leaves. The curvy, connected leaf veins found in some plants are an efficient way to circumvent damaged areas and channel nutrients, report researchers led by Eleni Katifori of the Rockefeller University in New York City.
"It's obvious that if you look at leaves, they have a lot of loops," Katifori says. To find out how the looped networks may be beneficial for the plants, the researchers created a computer model to compare how efficiently different branching patterns could do the job of leaf veins, which move water and nutrients around. "The question we're asking is, what's the best network we can build?" Katifori says.
In the simulations, the looped network performed better than nonlooped ones in several important ways, the team reported Jan. 29 in Physical Review Letters. Damage from hungry insects, cold weather or parasites can interrupt leaves' normal venation patterns. Connected circular veins allowed the flow of water and minerals to circumvent areas where veins were destroyed, the team shows. The looped network also allowed leaves to easily adjust the flow rate of water through veins, which can help leaves conserve water on a hot day, Katifori says.
Loop networks aren't found just in tree leaves. Blood vessels in the retina, structural veins in insect wings and the architecture of certain corals are all based on loops, the researchers write. Understanding the benefits of such networks might lead to more efficient man-made network designs.
Videos: 1) Looped vein network grows around a damaged spot./Eleni Katifori. 2) Straight veins are stopped by a damaged spot./Eleni Katifori.
Posted: 04 Feb 2010 01:43 PM PST
After more than four years of processing on20 hand-built computers, the bestviews evercaptured of Pluto are now available.
Working from 384 images taken by the Hubble Space Telescope in which the image of Pluto itself was just a few pixels across, astronomer Marc Buie and his team at the Southwest Research Institute stitched together the maps of Pluto you see here.
"It also shows you what I consider to be my best guess for what the true color of Pluto would be if you were puttering around near it in a spacecraft," Buie said in a NASA teleconference.
Pluto has mostly been in the news in recent years for its demotion from planet to dwarf planet and subsequent attempts to get it lumped back in with the bigger, round objects of the solar system.
But astronomer Mike Brown of the California Institute of Technology, aka @PlutoKiller on Twitter, said the question of the classification of the celestial body doesn't merit the attention it's gotten.
"That's really not an interesting question to ask," said Brown, who was not involved with the research. "It's a great place to study."
Specifically, what's fascinating to Brown and Buie is the tremendous amount of change that has been observed on Pluto, particularly between images obtained in 1994 and 2003. Based on the new processing of the photos, there has been more change on Pluto than Earth or Mars.
"You're looking at the surface in the solar system where there are the biggest changes we've ever seen," Brown said.
The color of the surface of Pluto changed so markedly, particularly between 2000 and 2002, thatBuie hasspent years checking and rechecking his work, just to make sure the differences weren't an artifact of faulty equipment or calculations.
"I got that result years ago but it's just so hard to understand and believe that I've been checking everything that I can think of," he said. "I'm still nervous about it. It could be that I've just completely screwed this up, but I can't find where."
One thing that gives him confidence is that one of Pluto's moons, Charon, is also in the image they have of the dwarf planet and its color remained constant as Pluto's changed. That makes it less likely that something went haywire in the instrumentation or processing.
The computing power necessary to turn the pixels of Pluto into the global map seen above as considerable. Buie handwrote all the code in a combination of IDL, a scientific programming language, and C. But when he finished and began to crunch the data, it appeared that it would take decades for the calculations to complete.
So, he took the funding he had and scrapped together 20 computers to do the work in parallel.
"I bought these little shuttle boxes and a processor and memory. I got [the price] down to $450 per computer and I had enough to buy 20 computers and have them all grind," he said. "That's about the cheapest supercomputer you can manage."
Planet or not, Pluto will now provide a lens for studying the rest of the objects in the Kuiper Belt beyond Neptune.
"Even though Pluto is not the biggest one it's the closest one and the best one to study," Brown said, "and to help us interpret all these other things we're seeing in the outer solar system.
Image and Video: NASA, ESA, and M. Buie (Southwest Research Institute)
Posted: 04 Feb 2010 01:21 PM PST
Another week, another colorful feathered dinosaur. Hot on the heels of a recent report identifying pigments in fossilized dino feathers and filaments (SN Online: 1/27/10), a different team of scientists says that it has mapped the full pattern of plumage sported by the oldest known feathered dinosaur.
Paleontologists first described Anchiornis huxleyi, which lived in what is now northeastern China between 151 million and 161 million years ago, in September (SN: 10/24/09, p. 8). Reports of the lithe, peacock-sized dinosaur caused quite a stir, not least because the feathered creature was older than Archaeopteryx, which is considered by many scientists to be the oldest known bird.
Now, analyses of fossil feathers from all parts of A. huxleyi's body — reported online Feb. 4 and in an upcoming Science — provide a detailed look at the dino's color scheme. The new findings also bolster the notion that feathers first evolved for a purpose other than flying, scientists say.
A. huxleyi had black and gray body plumage, the team's investigations suggest. And while the long feathers on the front and side of the creature's crest were gray, those sprouting from the top and back of its head were reddish-brown. Along with reddish-brown spots on its head and neck, A. huxleyi sported white racing stripes on its legs and its winglike forelimbs.
Paleobiologist Jakob Vinther of Yale University and his colleagues took a microscopic look at fossilized feathers at 29 sites on a specimen of A. huxleyi unearthed early last year. Some analyses focused on the small, simple feathers that covered the creature's body and skull, and others targeted the longer, more complex feathers that adorned its forelimbs, legs and feet. "There was hardly any part of the creature that wasn't feathered," Vinther notes.
Almost all of the feathers the team scrutinized contained well-preserved remnants of pigment-bearing structures called melanosomes. Feathers lacking melanosomes were probably white, the researchers note. By comparing the size, shape, density and arrangement of melanosomes in each fossil feather with those in variously colored feathers of modern birds, the team then sketched out what A. huxleyi looked like. "Using those comparisons, we can reliably predict [the creature's] color and map the whole animal," Vinther says.
The team's analyses "reveal an enormous array of information," says Michael Benton, a paleontologist at the University of Bristol in England. The black-and-white bars on A. huxleyi's forelimbs, as well as its colorful crest, are reminiscent of similar features in modern birds, he adds.
Knowing when color appeared in feathers or filaments may help solve the conundrum of why those structures evolved in the first place, Benton says. After all, he notes, A. huxleyi's feathered forelimbs weren't sufficiently large enough to carry the creature's weight in flight. "What's the function of half a wing?" he asks. The fact that feathers appear in the fossil record long before flight-capable birds suggests that feathers initially served a behavioral function, possibly one related to sending visual signals, and only later began to serve an aerodynamic function.
Philip J. Currie, a paleontologist at the University of Alberta in Edmonton, Canada, agrees: "Ancient creatures didn't just sprout feathers and start flying. The feathers were there for another reason first." Fossils reveal that dinosaurs often had very large eyes and sizable optic lobes in their brains. "Dinosaurs were very visual animals, just like birds are," he adds.
Bold patterns of plumage, such as those seen in A. huxleyi, could have served any of a number of functions, Vinther and his colleagues speculate. Besides communicating to members of its own species — a "come here, cutie" to members of the opposite sex, say, or a "back off" message to rival suitors — a quick flash of boldly colored plumage could startle an attacking predator or flush prey out of hiding, the researchers say.
Images: © 2010 National Geographic
Posted: 04 Feb 2010 11:51 AM PST
Aerial imagery of Europe in 1943 that shows the devastation of World War II is now available in Google Earth. Comparing photos such as those above of Warsawbefore the war, mmediately after the war and today really brings to life the incredible destruction and amazing recovery of bombed European cities.
Around three dozen cities have images available from 1943 in Google Earth's historical imagery feature including Lyon, France, Naples, Italy and Stuttgart, Germany, all pictured below. The aerial perspective highlights the extent of the demolition.
One of the most striking sets of photos is of the Warsaw ghetto below in 1935, 1943 and present day. It was the largest ghetto in Europe and hundreds of thousands of Jewish people were deported from there or killed there.
The images above show the same time sequence for Warsaw's Old Town at top and Warsaw University.
Posted: 04 Feb 2010 11:27 AM PST
After warning for years that athletes would try to dope their genes, scientists are finding ways to catch them. The tests are still being refined in animals, but will likely berun years from now on samples taken at the upcoming Winter Olympics and stored.
The tests reflect a new approach to doping detection: Rather than targeting specific, easily masked chemicals, they look at system-wide changes in gene expression and protein production.
"Before, drug testers took a toxicological approach," said Olivier Rabin, science director at the World Anti-Doping Agency. "Now we're on much more of a medical and forensic approach."
The International Olympic Committee formally banned gene doping in 2003, when gene therapy and gene-targeting therapeutics were mostly a matter of medical prediction. Since then, they've moved to the edge of medical reality. Most advances are still limited to lab animals, but that hasn't stopped athletes from hoping for an early if unproven edge.
Bodybuilding magazines already carry advertisements for DNA-tweaking drinks and pills. Experts say these are fraudulent, but reputable researchers are routinely contacted by coaches and athletes wondering if their animal treatments can be given to humans.
Three years ago, German track coach Thomas Springstein was busted after unsuccessfully trying to score Repoxygen, an experimental gene therapy drug that boosts red blood cell production, for his runners. At the Olympics in Beijing, an unidentified Chinese doctor offered stem cell injections to a German journalist posing as a swim coach.
"We have no evidence that any athlete bought or used that stuff," said Mark Frankel, an American Association for the Advancement of Science bioethicist who studies gene doping. "But the next big movement forward in terms of cheating is very likely to be in the genetic arena."
The most likely biological targets for cheating are erythropoietin, the protein enhanced by Repoxygen; genes for the production of myostatin and insulin-like growth factor I, which affect muscle production (as in the lower mouse in the photo); and peroxisome proliferator-activated receptors, a family of proteins that regulate metabolism and have been touted as providing "exercise in a pill."
For now, none of these boosts can be detected. But all of them are being studied by researchers supported by the World Anti-Doping Agency, who have sponsored dozens of test-developing projects.
Some of the tests are aimed at detecting immediate evidence of doping: leftover fragments of engineered viruses used by gene therapists, telltale proteins, obviously modified DNA sequences, and so on.
But this is difficult. Such evidence is hard to find and degrades quickly in the body. Moreover, even if a first generation of tests are successful, they could be tricked by slight changes to gene-modifying approaches.
Instead, researchers are looking for broader changes that are produced by gene modification and can't be masked. Tweaking insulin-like growth factor, for example, appears to change levels of fatty acid production and body-wide protein expression in ways that can't be masked.
"The concept is that if you suspect doping, you don't look for the drug, but for the effects of the drug on global gene expression and proteomic patterns," said Theodore Friedmann, a University of California, San Diego geneticist who's now combining results from WADA-supported research into statistical models of cheating. "Even if someone makes a chemical change to a drug to make it invisible to testing, they can't wipe out the effects of the drug."
This approach could end up being applicable not only to genetic modification, but to changes produced by traditional performance enhancers, like steroids and growth hormone.
Friedmann cautions that much work remains to be done on these tests, which are still limited to animal studies. But even if they take years to be refined, the tests could be used on biological samples already taken from elite athletes.
"We have to make sure the changes we find aren't caused by gender or nutrition or training, and there are issues with genetic privacy," said Friedmann. "But the samples can be put away for up to eight years. We can go back to them later."
Could even these system-wide tests be duped?
"Anything you do to your body changes your body," said Rabin. "Is there a perfect crime? Many investigators will tell you no."
Posted: 04 Feb 2010 09:43 AM PST
Federal court hearings continued Tuesday on a lawsuit that could transform biotechnology in the United States by eliminating gene patents.
The case hinges around the claims of Utah-based Myriad Genetics on BRCA1 and BRCA2, a pair of genes closely linked to breast and ovarian cancer. Myriad "owns" the genes, and saysits patents make it possible to profit on diagnostic tests. The company argues that if you remove the patents, the tests — indeed, commercial biotechnology as we know it — will vanish.
Acoalition of civil rights, research and women's health groupsis fighting the patents. They argue that Myriad's claims stifle innovation by discouraging researchers from looking at the genes, which are still not fully understood, and say Myriad's monopoly limits women's health choices. More broadly, the claims set a precedent for other gene patents, which now cover about one-fifth of the human genome.
"Allowing patents on genetic material imposes real and severe limits on scientific research, learning and the free flow of information," said Chris Hansen, an attorney with the America Civil Liberties Union, in a press release.
At Tuesday's hearing, defense attorney Brian Poissant insisted that "'women would not even know they had BRCA gene if it weren't discovered' under a system that incentivizes patents," reported GenomeWeb Daily News.
But much of the scientific community rejects Myriad's case. Roughly 150,000 researchers are represented by associations that have filed court briefs supporting the plaintiffs. Among them are the American Medical Association, American Society of Human Genetics and March of Dimes.
In his recent book, The Language of Life: DNA and the Revolution in Personalized Medicine, National Institutes of Health director Francis Collins also argued against broad gene patents.
"The information contained in our shared instruction book is so fundamental, and requires so much further research to understand its utility, that patenting it at the earliest stage is like putting up a whole lot of unnecessary toll booths on the road to discovery," he wrote.
In May, the court rejected Myriad's request that the case be thrown out without a trial. DuringTuesday's hearing, the plaintiffs asked to be declared victorious without a trial. A decision is expected to take several months.
If the court rules against Myriad, patents involving genes and other biological products won't be eliminated altogether. Instead, claims will need to be made on specific types of tests or modifications, rather than the discovery of something that exists in nature. The ACLU likened Myriad's claim to that of someone who patents gold after panning a few nuggets from a stream.
A case memo filed by the plaintiffs called Myriad's prediction of industry doom "pure hyperbole." They cited a 1931 Supreme Court decision that struck down the American Fruit Company's claimed ownership of fresh fruit.
"To be sure, the fruit industry survived," wrote the plaintiffs.
For full documentation of the case, see "Association for Molecular Pathology, et al. v. U.S. Patent and Trademark Office, et al."
Posted: 04 Feb 2010 06:30 AM PST
Just a week at high altitudes can cause sustained weight loss, suggesting that a mountain retreat could be a viable strategy for slimming down.
Overweight, sedentary peoplewho spent aweek atan elevation of 8,700 feet lost weight while eating as much as they wanted and doing no exercise. A month after they came back down, they had kept two-thirds of those pounds off. The results appear in the Feb. 4Obesity.
"What is nice about this paper, is that it clearly demonstrates that there's a lasting effect of decreased caloric intake, that people eat less even a month after they come out of high altitude," said Massachusetts General Hospital anesthesiologist Kay Leissner, who studies high altitude physiology, but was not involved in the study.
Since a 1957 study, scientists have known that animals lose weight at high altitudes. Mountaineers also shed pounds during expeditions to 12,000 feet or more, though the exertion of climbing a mountain clearly played a role.
But the obese aremore likelyto suffer severe altitude sickness, in which low oxygen pressure causes dizziness, nausea and more serious problems like edema or heart attacks, Leissner said.
So a team at Ludwig-Maximilians University in Munich wanted to see if the pounds also melted away with a safer, sedentary stay at somewhat lower altitude.
The scientistsferried 20 overweight, middle-aged men by train and cable car to a research station perched 1,000 feetbelow the peak of Germany's highest mountain, Zugspitze. During the week-long stay, the men could eat and drink as much as they liked and were forbidden from any exercise other than leisurely strolls. The teammeasured the men'sweight, metabolic rate, levels of hunger and satiety hormones before, during, and after their mountain retreat.
After a week up high, the subjects lost an average of3 pounds. A month later, they were still2 pounds lighter. The sceintists' data showed this was likely because they ate about 730 calories less at high altitudes than they did at normal elevations. They may have felt less hungry, in part, because levels of leptin, the satiety hormone, surged during the stay, while grehlin, the hunger hormone, remained unchanged. Their metabolic rate also spiked, meaning they burned more calories than they usually did.
A high-altitude weight loss strategy could be viable, though studies have shown peoples' appetites bounce back after about six months at high elevation, Leissner said. "If you could do intermittent periods for one week, then go down, and then go back up, this might actually be helpful."
One limitation of the study, however,is that it didn't show whether the men lost mostly muscle mass, fat, or water weight,Leissner said.
And the study didn't show that the stay at 8,700 feet was actually safe for the participants, University of Geneva exercise physiologist Bengt Kaysersaid in an e-mail.
New research into why the overweight are prone to heart attacks, diabetes, and other inflammatory diseases, suggest it could be some fat cells grow so rapidly that blood vessel growth can't keep up, and that leads to pockets of oxygen-starved fatty tissue, Kayser said."This causes local inflammation because immune cells get activated."
If that's the case, then shuttling the overweight to even a moderate altitude may worsen inflammation and increase their chances of heart attack or other serious problems.
"So for the moment one has to remain very careful," Kayser said,"and evaluate the question a few more times before migrating all obese Americans to Colorado!"
Image: Zugspitze, Stephan A./flickr
Citation: "Hypobaric Hypoxia Causes Body Weight Reduction in Obese Subjects," Florian J. Lippl, Sonja Neubauer, Susanne Schipfer, Nicole Lichter, Amanda Tufman, Bärbel Otto, and Rainald Fischer. Obesity, 4 February 2010.
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