- Cockroach Brains, Coming to a Pharmacy Near You
- Flying Fish Ace Wind-Tunnel Tests
- Earth’s Most Stunning Natural Fractal Patterns
- Early Warning Signs Could Show When Extinction Is Coming
- Carbon Emissions Not at Doomsday Level … Yet
- Rare, Tiny, Supercute Baby Seahorse Found in British Waters
- 1976 Look at Mars Soil May Have Missed Life’s Building Blocks
- Close-Shave Asteroid Caught on Camera
- Native Toad Fights Back Against Yellow Crazy-Ant Invasion
- DIY Laser-Safety Update: There’s an Easier Way
Posted: 10 Sep 2010 10:58 AM PDT
Cockroaches may be nasty bugs, but they could help fight even nastier ones. New research finds that the rudimentary brains of cockroaches and locusts teem with antimicrobial compounds that slay harmful E. coli and MRSA, the antibiotic-resistant staph bacterium. The work could lead to new compounds for fighting infectious diseases in humans.
Extracts of ground-up brain and other nerve tissue from the American cockroach, Periplaneta americana, and desert locust, Schistocerca gregaria, killed more than 90 percent of a type of E. coli that causes meningitis, and also killed methicillin-resistant staph, microbiologist Simon Lee reported Sept. 7 at the Society for General Microbiology meeting at the University of Nottingham in England.
"Some of these insects live in the filthiest places ever known to man," says Naveed Khan, co-author of the new study. "These insects crawl on dead tissue, in sewage, in drainage areas. We thought, 'How do they cope with all the bacteria and parasites?'"
Khan and his colleagues became intrigued by insect antimicrobials when they noticed that many soldiers were returning from the Middle East with unusual infections, yet locusts living in the same areas were unperturbed. So the researchers, all from the University of Nottingham, began investigating how the insects ward off disease.
The team ground up various body parts from both cockroaches and locusts that had been reared in the lab and incubated them for two hours with different bacteria. Leaving these mixtures overnight on petri dishes revealed that the extracts from brains and from locust thorax nerve tissue killed nearly 100 percent of the bacteria.
Yet the insect brain extracts didn't seem to bother human kidney or epithelial cells when grown with them in a lab dish.
Curiously, extracts of insect fat, muscle and blood didn't bother the bacteria at all. Cockroaches and locusts often eat stuff loaded with microbes, says parasitologist Carl Lowenberger of Simon Fraser University in Burnaby, Canada, so you would think insect guts and blood, which bathes the organs, would have similar antimicrobial activity.
Nine molecules appear to be responsible for the antimicrobial activity in locust tissue, although they have yet to be identified. The team is also still working out the details of the cockroach compounds.
The compounds may work together as a cocktail, Lowenberger says. Insects make hundreds of antimicrobial compounds, and it may be that very high concentrations of those molecules would be required for fighting an infection in humans. But the research "is pretty neat stuff," he says. And perhaps down the road, the yet-unidentified molecules will prove useful in fighting infections in people.
Posted: 10 Sep 2010 09:13 AM PDT
Put flying fish in a wind tunnel, and they're as aerodynamically polished as most birds.
Earlier analyses of their bodies suggested as much, but the calculations were hypothetical.
"We directly measure the aerodynamic forces," wrote aerospace engineers Hyungmin Park and Haecheon Choi of Seoul National University in a Sept. 10 Journal of Experimental Biology paper. "The gliding performance of flying fish is comparable to those of bird wings such as the hawk, petrel and wood duck."
Park and Choi's specimens were caught in the Sea of Japan and formally belonged to Cypselurus, a flying fish genus with a cylindrical body, exceptionally broad pectoral fins and unusually developed pelvic fins near its tail. Another genus, Exocoetus, has narrower pectoral and smaller pelvic fins; researchers liken them to biplanes and monoplanes (.pdf).
Propelled by a tail-motor action on the surface of waves, the fish regularly make gliding flights of more than a hundred feet, at speeds above 30 mph. (In a widely circulated video shot from a Japanese ferry, a fish stayed aloft for 45 seconds.) Flying helps the plankton-eating fish escape from predators.
With the fish dry-mounted and filled with urethane to maintain shape (.pdf) in wind tunnel tests, Park and Choi were able to measure the fishes' lift-to-drag ratios, how far they moved horizontally per unit of vertical fall, and other aerodynamical measures.
At their precise angle of exit from the water, the fish achieve their greatest lift. The fin arrangement pushes air down the fishes' bodies towards their tails, like a jet. And when the fish are just above the water's surface, they benefit from a ground effect, in which air pressure underneath their fins creates lift.
The researchers are now curious about the potential role of texture differences between the top and bottom of flying fish pectoral fins.
The pair are also designing a flying fish-inspired plane. In an e-mail, Choi gave few details, but it would appear to be quite low-flying.
"The ground effect for reducing the drag force is very important in the design," he said.
Images: 1). Diagram of flying fish in wind tunnel, and depiction of air flow around its body at a flat (top) and 10 degree (bottom) angle./Journal of Experimental Biology. 2) Diagram of flying fish./JEB.
Citation: "Aerodynamic characteristics of flying fish in gliding flight." By Hyungmin Park and Haecheon Choi. Journal of Experimental Biology, Vol. 213 Issue 18, September 2010.
Posted: 10 Sep 2010 04:00 AM PDT
<< Previous | Next >>
Posted: 09 Sep 2010 11:55 AM PDT
Animal populations headed for extinction may give the same signals seen before crashes in coral reefs, the Sahara's climate and even stock markets.
These systems are very different, but each exhibits what's known as "critical slowing down," in which a loss of resilience magnifies the effect of small perturbations, which become more and more difficult to recover from.
"Critical slowing down is an early warning signal. If you can detect it, you can know that you're headed for a tipping point," said University of Georgia ecologist John Drake. "This could lead to new ways of quantifying population viability."
Critical slowing down in animals was theoretically predicted, and has now been demonstrated in laboratory populations of water fleas. If it can be detected in real-world populations of other animals, scientists could have a valuable new tool for telling when animals are literally on the brink of extinction.
On the surface, predicting extinction risk seems like it should be easy: It's generally the result of habitat loss, exploitation, and factors like disease or invasive species. But with these conditions changing constantly, modeling is often difficult, and it can be hard to tell exactly when the threat of extinction has gone from predicted to imminent.
Drake, who specializes in population dynamics, wanted to see whether the emerging science of so-called critical transitions — the sudden flip of a system from one condition to another, originally identified in physics and recently applied to ecology — also applied to animals. At least theoretically, their populations should behave in similar fashion when approaching the critical transition that is extinction.
In a study published Sept. 9 in Nature, Drake and University of South Carolina biologist Blaine Griffen tracked population changes in 60 laboratory colonies of water fleas. Half were given a steady food supply, while the others received one-quarter less food every month. Lacking the nutrients needed to reproduce more frequently than they died, the latter colonies inevitably went extinct, long before the food ran out.
In any animal population, the number of individuals oscillates naturally. A few extra offspring are born, putting a strain on resources; that leads to a few extra deaths or a drop in births, which frees up resources that allow the population to grow again. These fluctuations converge on an equilibrium somewhere in the middle. Both the control and nutrient-deprived populations followed this pattern.
But when Drake and Griffen looked closely at the data from declining groups, they found that populations took much longer to return to equilibrium. That's a telltale sign of critical slowing down. Under too much stress, a system loses its balance easily, and takes longer to recover that balance. It was evident up to eight generations before extinction.
"Critical slowing down refers to the resilience that a system has, its ability to recover from perturbations," said Drake. "A tipping point is a condition when that ability to recover goes all the way to zero. As you're getting closer, it takes longer and longer for each perturbation to die down."
The equations generated by the cycles of water flea populations matched those seen in other systems as they approached their own critical transition points — the then-verdant Sahara before turning to desert 5,500 years ago, once-clear freshwater lakes turned by nutrient pollution into algae-choked soup, even the stock market prior to its 1987 crash.
Wageningen University ecologist Marten Scheffer, a pioneer in critical transition research, called the findings a "really important step" in learning how to detect impending tipping points in animal populations. But he warned that detecting signals in real-world conditions is harder than in a laboratory.
Such experiments are currently being run by University of Wisconsin ecologist Steve Carpenter, who has turned several lakes into field laboratories for detecting ecosystem shifts. "It's too early to draw conclusions, but so far it seems promising," said Carpenter.
Another useful experiment would be to measure the results of interventions at different points in the water fleas' slide to extinction. That might hint at when an early warning sign turns into a foregone conclusion.
Drake's resources have been stretched thin, but "that would be a fantastic experiment, and I would love for someone to do it," he said.
Images: 1) Male and female water fleas./West Group, Oxford University. 2). Differences between control and food-deprived populations in two measures of critical slowing down./Nature.
Citation: Early warning signals of extinction in deteriorating environments John M. Drake & Blaine D. Griffen. Nature, Vol. 467 No. 7313, September 9, 2010.
Posted: 09 Sep 2010 11:00 AM PDT
There are two doomsday numbers in climate change discussions: 2 degrees Celsius and 450 parts per million. Groups of climate scientists like the Intergovernmental Panel on Climate Change generally agree that if the world warms more than 2 degrees above pre-industrial levels, which would put the concentration of carbon dioxide in the atmosphere at 450 parts per million, the ramifications of global warming get exponentially worse.
But some scientists wonder if we're already there. Climate energy scientist Steven Davis of the Carnegie Institution's Department of Global Energy and colleagues posed a hypothetical: What would happen if the whole world suddenly stopped building new carbon dioxide emitters, from coal plants to cars, and let the existing ones die naturally of old age? Will the carbon emitters of today push us over the limit, no matter what we do next?
Not just yet, Davis claims in a paper in the Sept. 10 Science. But just because we're not doomed yet doesn't mean we can relax.
"The currently existing infrastructure is not going to create the worst impact of climate change," Davis said. "The devices whose emissions will have the worst impact have yet to be built."
Davis and colleagues compiled data sets on power plant emissions, motor vehicle emissions, and household, business, industrial and transportation emissions, plus historical data on how long technologies like cars and power plants generally last. A coal-fired power plant's natural lifetime is about 40 years, for example, while a car in the United States usually lasts around 17 years.
They calculated that existing emitters will blow between 282 and 701 gigatons of carbon dioxide into the atmosphere between 2010 and 2060, which would keep the atmospheric concentration of carbon dioxide below 430 parts per million. These levels of carbon dioxide would result in warming of only 1.1 to 1.4 degrees above pre-industrial levels, even at the upper limit of their estimates.
"We were pleasantly surprised that we came in under those benchmarks," Davis said. "The fact that existing infrastructure doesn't put us over these common benchmarks is good news."
But it's good news with an asterisk: There's no way the world will stop building new carbon emitters tomorrow. The social and political inertia surrounding issues of energy and climate could take years or decades to reverse.
"These scenarios drastically underestimate the time to transition to this carbon-free energy system," Davis said. "To actually get anywhere close to the scenario we've come up with would require a tremendous ramp-up of carbon-free technology."
The study highlights "the draconian reductions in emissions that would be necessary to prevent that [disastrous climate change] from happening," commented physicist and climate scientist Martin Hoffert of New York University. Hoffert thinks it will take a revolutionary change in our energy system to get out of the danger zone.
"We would have to do something like what FDR did in World War II, just say look, this is a matter of survival, we're not going to worry about money," he said. "We really will need to make major investments as a society in research and development in alternate energy. We don't have this stuff sitting on a shelf."
Hoffert also noted that combating climate change is not about saving the planet. The planet has already gone through several periods of extreme warming, where carbon dioxide levels soared and glaciers melted.
"The planet will survive," he said. "It's just that our civilization won't."
Image: Steven J. Davis
Posted: 09 Sep 2010 08:31 AM PDT
By Mark Brown, Wired UK
File this under A for adorable. The Seahorse Trust, after years of surveying the fish in British waters, has finally found, measured and photographed a baby seahorse, which is also called a fry.
Despite finding many adults, plenty of pregnant males (female seahorses transfer their eggs to the male, who fertilizes them in his pouch) and juveniles, the trust had previously failed to find any babies.
Baby seahorses are left entirely on their own after being born, and rarely survive long enough to become an adult. Due to their premature independence and underwater predators, less than one in a thousand will survive into adulthood. Not good odds, even though about 100-200 eggs are hatched at a time.
But the trust finally found a fry in the waters at Studland in Dorest. Despite poor weather and only 3 feet of visibility, scientists spotted a tiny seahorse clinging on to a piece of seagrass. They managed to measure the 1.6 inch creature, and snap the photograph above, before the baby returned to the sea bed.
In the first few weeks of a seahorse's life, it will live predominantly in the plankton layer of the ocean, gobbling up an astounding 3,000 pieces of plankton every 24 hours.
But unfortunately, seahorses are under threat around the world as they're popular as pets, souvenirs and in Chinese medicine. An excess of 20 million of the critters are taken from the sea each year and used in Asia to treat ailments like asthma, impotence, thyroid disorders, broken bones and heart disease.
In the U.K., however, it is illegal to kill, take or disturb seahorses in British waters.
Image: The Seahorse Trust
Posted: 09 Sep 2010 07:29 AM PDT
Martian soil could contain the building blocks of carbon-based life after all, a new study suggests, despite the negative results of an analysis performed by the Viking missions 34 years ago.
When the Viking landers touched down on Mars in 1976 and scooped up soil samples, scientists were surprised that the two craft failed to unearth evidence that the Red Planet contained any organic compounds. The apparent lack of organic molecules — a basic requirement for carbon-based organisms — helped to cement the notion of Mars as an entity that would not easily support life.
But a new study, which relies on soil samples from Earth, now suggests that the Viking craft may have found organic compounds from Mars but failed to recognize them. The finding represents a sea change in the way many scientists think about Mars and suggests a specific strategy for searching for vestiges of life on the planet, says study co-author Rafael Navarro-González of the National Autonomous University of Mexico in Mexico City.
Navarro-González and his collaborators, including Chris McKay of NASA's Ames Research Center in Moffett Field, California, describe their work in an upcoming Journal of Geophysical Research–Planets. They also reported the findings Sept. 6 during a press briefing from the National Autonomous University.
The study was inspired by an analysis of soil samples conducted by the Mars Phoenix Lander, which arrived in the north polar region of Mars in May 2008 and operated for five months. Phoenix found that most of the chlorine at the landing site was in the form of perchlorate, rather than a chloride salt as had been assumed.
Perchlorate is an oxidizing agent that when heated, breaks down into highly reactive fragments that destroy organic compounds. These reactions take place at the same temperatures — 200° to 500° Celsius — to which Martian soil samples were heated by the Viking craft. The only organic compounds found by Viking, chloromethane and dichloromethane, were interpreted as contaminants from Earth, since they are common in cleaning fluid, solid rocket fuel, fireworks and other explosives.
But when Navarro-González and his colleagues added 1 percent by weight magnesium perchlorate to soil from the Atacama Desert in Chile, which is thought to closely resemble Martian soil and is known to contain organic compounds, they found an intriguing result. Heating the perchlorate-adulterated desert soil to temperatures comparable to those in the Viking experiments produced the same chlorinated organic compounds that were found by the landers in 1976 but dismissed as contaminants. Nearly all the organic compounds originally in the Chilean soil were destroyed during the heating.
Similarly, the team says, the soil at the two Viking sites likely contained plenty of organics that were destroyed upon heating and were turned into chlorinated methane compounds due to the presence of perchlorate.
"The bottom line of this work is that the Viking landers did detect organics on Mars, we just did not realize it," McKay asserts. He and his colleagues estimate that the Martian soil contains a few parts per million of organics, comparable with the driest parts of the Atacama Desert.
But astrobiologist David Des Marais of NASA-Ames cautions that the study's authors can't be sure that the Chilean desert soil that they analyzed closely resembles the Martian soil. In addition, he notes, the inorganic compounds in the Chilean samples could alter the nature of the materials released during the heating process.
The presence of organic compounds on Mars at concentrations of parts per million does not mean that the Red Planet, now cold and arid, is a gentler, kinder place for life, McKay says. Nor does it require that life exists or once flourished there, the researchers emphasize.
Meteorites could have delivered the compounds to the planet, rather than a biological source. However, the presence of organic compounds opens up a relatively easy way to search for life on Mars, the researchers say.
If Mars contained organic compounds at concentrations of only parts per billion or less, searching for such signs of life as DNA, complex proteins or energy-carrying adenosine triphosphate would be problematic. But if Mars contains organic compounds at the level of parts per million, "then searching within these organics for such biomarkers makes sense," McKay says. Moreover, scientists are particularly adept at searching for these biomarkers, he adds.
For Des Marais, however, searching for Martian DNA "is out of the question" because the molecule is too fragile.
NASA's Curiosity Rover, scheduled for launch in November 2011, has the ability to search for organic compounds by adding liquid to soil samples, which would not subject them to the high temperatures at which perchlorate destroys organic compounds, notes McKay.
"I'm very excited about the possibility that in a couple years, we will have a follow-up mission that will use the information that comes from this study to detect and confirm the organics on Mars," he says.
Image: Photograph of Mars surface taken by the Phoenix lander one day after arrival./NASA.
Posted: 08 Sep 2010 11:45 AM PDT
When asteroid 2010 RX30 zipped past Earth early Wednesday, observers at the Remanzacco Observatory in Italy were ready. At 12:45 a.m. Mountain time, amateur astronomers Ernesto Guido and Giovanni Sostero remotely controlled a 0.25-meter telescope in Mayhill, New Mexico, through the Global Remote Astronomy Telescope Network. They got four separate exposures of 30 seconds each and stitched them together to make this animation.
At its closest approach, 2010 RX30 was about 154,100 miles from Earth, or 60 percent the distance between the Earth and the moon.
Another asteroid, 2010 RF12, swung past Earth at a distance of 49,000 miles (20 percent the Earth-moon distance) at 5:12 p.m. EDT (0012 UT Thursday). Check back for more photos of these cosmic interlopers in action.
Image: Ernesto Guido and Giovanni Sostero
Posted: 08 Sep 2010 11:24 AM PDT
After so many sad tales of invasive species overwhelming hapless natives, scientists have found a native toad in Indonesia that's fighting back.
Yellow crazy ants get their name from their color and their zigzag scurrying, and they have crowded out native ants and disrupted ecosystems elsewhere. The invaders meet any foe aggressively, releasing noxious chemicals during battle. The Sulawesi toads eat them nonetheless, Wanger says.
During a week of toad abundance on Sulawesi farms, test plots hopping with toads had as little as one-third of the invasive-ant populations found on plots where fencing kept toads out, Wanger and his colleagues report in a paper released online the week of Sept. 6 in Proceedings of the Royal Society B.
The paper could be a first in suggesting that a native toad might control populations of invasive ants, says ecologist Stacy M. Philpott of the University of Toledo in Ohio. "It is a really neat finding," she says.
Wanger and his colleagues established that the toads disproportionately prey on ants, based on the toads' fecal samples. "You wouldn't believe how smelly these things are," he says. The samples revealed that some kind of ant accounted for three-quarters of the diet of the toads storming through the test region, even though ants didn't represent a large proportion of the arthropods there. Native ants presumably have long coexisted on the island with the toads, but populations of invaders may be taking a hit, the researchers suggest.
The test plots lay in cacao plantations, and the researchers speculate that the toads' taste for ants may turn out to be a boon for cacao pest control. About every three months, the toads leave their usual forest home and surge through the cacao plantations to breed in the water of neighboring rice fields.
Toads feasting on yellow crazy ants may help keep the invaders from crowding out the native ants in cacao plantations. Other researchers have shown that a rich diversity of native ants helps keep cacao pests and diseases in check.
The study's suggestion that the Sulawesi toads ultimately help control pests in the cacao plantations is plausible, Philpott says. She and a colleague have surveyed the scientific literature on how the diversity of ants can affect diseases and pests in coffee and cacao plantations. One kind of native ant preys on insects that leave sticky lesions on cacao pods, for example, and fewer sticky spots means the pods attract fewer visits from flies tainted with a pathogen causing pod rot.
Making a case for toads as protectors of cacao might rouse new enthusiasm for protecting native amphibians, as Sulawesi residents have similar priorities to those in agricultural communities the world over. "They are not really interested in biodiversity conservation but in economic questions," Wanger says.
A scientist who has studied the ecological damage from crazy ants, Dennis O'Dowd of Monash University in Melbourne, Australia, notes that the researchers now need to investigate the other links in their hypothesis, such as whether the toads' periodic gorging on yellow crazy ants has a lasting effect on ant populations.
Nonetheless, he says, "I certainly like the sentiments in the paper, and I'm all for conservation of native amphibians."
Posted: 08 Sep 2010 09:23 AM PDT
A few weeks ago we posted a story about how some green laser pointers leak dangerous amounts of eye-damaging infrared light, and outlined a home-brew way to test your own laser pointers.
That test involved balancing the laser pointer on a cup, shining it at a CD and photographing the resulting light patterns with two different cameras. But biochemist Jody Plank and physicist Chris Dombrowski of the University of California, Davis say there's an easier way: Just use an infrared thermometer.
"This is an elegant example of what I hoped would come from our publishing a paper on the green laser problem: that others would find even more accessible and convenient ways to diagnose it," said National Institute of Standards and Technology physicist Charles Clark, a coauthor of the original study, in an email to Wired.com.
Infrared thermometers measure the heat output of an object without having to touch it. Rather than directly measuring a heated object's temperature, the thermometers measure how much the object is radiating in the infrared part of the electromagnetic spectrum, and convert that measurement to degrees.
Plank was trying to replicate the setup suggested in the earlier study, "when Chris came in and had this brainstorm" to use the lab's infrared thermometer instead, Plank said. Infrared thermometers are useful in biology labs like Plank and Dombrowski's, where sticking a conventional thermometer into an agar plate or a water bath would contaminate biological samples.
When the researchers' laser pointer was switched off, the thermometer read it as near room temperature. But when they turned it on, the thermometer went nuts, jumping as high as 185 degrees Fahrenheit. Despite the high temperature reading, the laser pointer was still cool to the touch.
"That was the first clue that we were measuring the infrared output of the laser and not an actual temperature," Planck said.
The pair caution that it's probably not simple to convert the temperature read by the thermometer to the energy output of the laser, but it is a way to qualitatively check if a laser is leaking a lot of infrared light. The researchers suggest taking several readings to make sure. And as in any home experiment involving lasers, it's best to wear safety glasses and keep the laser well away from your eyes.
Infrared thermometers are available on Amazon or from a well-stocked hardware store for about $50.
"The NIST method… allows people to set up a small optics physics lab right on their desk," Plank said. "The method that we came up with might be good for people who are not as inspired by doing their own physics experiment, but still curious about the safety of the laser they're using."
Via Bitesize Bio
Image: Anthony Forget
|You are subscribed to email updates from Johnus Morphopalus's Facebook notes |
To stop receiving these emails, you may unsubscribe now.
|Email delivery powered by Google|
|Google Inc., 20 West Kinzie, Chicago IL USA 60610|