LAKE VOSTOK MYSTERIES: BIOLOGISTS FIND OVER 3,500 LIFE FORMS IN ISOLATED ANTARCTIC BASIN.


Scientists have discovered more than 3,500 unique gene sequences in Lake Vostok – the underground Antarctic water reservoir isolated from the outside world for 15 million years – revealing a complex ecosystem far beyond anything they could have expected.

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“The bounds on what is habitable and what is not are changing,” said Scott Rogers, Bowling Green State University professor of biological sciences, who led a genetic study of the contents of half a liter of water brought back from the lake after it was drilled by Russian scientists last year.

“We found much more complexity than anyone thought,”
 Rogers said. “It really shows the tenacity of life, and how organisms can survive in places where a couple dozen years ago we thought nothing could survive.”

There are few places on Earth more hostile to life forms than Lake Vostok, the largest subglacial lake in the Antarctic, and initially Rogers believed that the water from it may have been completely sterile.

Water is located 4,000 meters below the ice, which completely blocks sunlight, and creates huge pressure on the liquid. It is also literally located in the coldest place on Earth: the world’s lowest temperature of -89.2C was recorded at Vostok Station above the reservoir.

But after using bleach to remove outer layers of the ice (the form in which the water was extracted from the lake) which could potentially have been contaminated during the drilling, and conducting RNA and DNA testing, thousands of microscopic life forms, predominantly bacteria, were detected.

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Many had expected that if any life forms were to be found in the frozen crypt, they would be uniquely adapted to the harsh environment, and perhaps entirely different as a result of being shielded from evolution of life elsewhere on the planet for millions of years.

Rogers, who has just published his findings in PLOS One magazine, says this has not turned out to be the case.

“Many of the species we sequenced are what we would expect to find in a lake. Most of the organisms appear to be aquatic (freshwater), and many are species that usually live in ocean or lake sediments.”

Rogers’ team believes the relative ordinariness of the organisms discovered may be due to the fact that they are left there as a legacy of when Antarctica had a temperate climate 35 million years ago, rather than as a result of evolution inside the lake.

Some of the organisms found in Lake Vostok commonly exist in ocean environments (in the digestive systems of fish and crustaceans) suggesting that the reservoir was once connected to a bigger body of saltwater.

But Rogers believes “two huge drops of temperature” cut it off and conserved it in its present state.

Yet the study is not excluding the possibility of startling discoveries.

“It’s a very challenging project and the more you study, the more you want to know. Every day you are discovering something new and that leads to more questions to be answered,” said Yury Shtarkman, who conducted many of the analyses, and believes it could take a lifetime to untangle the secrets of the lake.

 

Source: http://myscienceacademy.org

 

Wireless bio-absorbable circuits could kill bacteria.


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Remote-controlled, dissolvable electronic implants have been created that could help attack microbes, provide pain relief and stimulate bone growth.

The spread of bacteria resistant to antibiotics – popularly called superbugs – is threatening to put the clock back 100 years to the time when routine, minor surgery was life-threatening. Some medical experts are warning that otherwise straightforward operations could soon become deadly unless new ways to fend off these infections are found.

Bacteria often evolve clever ways of evading chemical assaults, but they will always struggle to resist the old-fashioned way of killing them: heating them up. It takes only a relatively mild warming to kill bugs without discomfort or harm to tissues. So imagine if little electric heaters could be implanted into wounds and powered wirelessly to fry bacteria during healing before dissolving harmlessly into body fluids once their job is done.

This is just one potential application of the bio-absorbable electronic circuits made by John Rogers of the University of Illinois at Urbana-Champaign and his co-workers. The idea itself is not new: Rogers and others have previously reported biodegradable flexible circuits and electronic devices that can be safely laid directly onto skin. But their success in making their circuits wireless could prove crucial to many potential applications, especially in medicine.

The hope is that radio waves can be used both for remote control of the circuits – to turn them on and off, say, and to provide the power to run them, so that there’s no need for implanted batteries. This kind of radio-frequency (RF) wireless technology is becoming ever more widespread, in food packaging, livestock labelling, tagging of goods in shops for security and in dustbins to monitor recycling, for example.

To make RF circuits, you need semiconductors and metals. Those don’t sound like the kinds of materials our bodies will dissolve, but Rogers and colleagues used layers of non-toxic substances so thin that they disintegrate in water or body fluids. For the metal parts, they used films of magnesium at least half as thin as the average human hair. Magnesium is not only harmless but in fact an essential nutrient: our bodies typically contain about 25g (0.9oz) of it already. For semiconductors, they used silicon membranes 300 nanometres (millionths of a millimetre) thick, which also dissolve in water. They used magnesium oxide as an insulating material when required.

Power scavenger

One of the simplest but most important components of an RF circuit is an antenna, which picks up the radio waves. Rogers and colleagues made these from long strips of magnesium foil deposited onto thin films of silk. Being non-toxic, biodegradable, strong and relatively cheap, silk makes the ideal base for such devices. These antennae, typically about four inches long, dissolve completely in water in about two hours. Although being buried beneath radio wave-absorbing body tissue would hamper performance, they should still receive enough signal for low power applications the researchers are considering.

The researchers have also made a variety of standard circuit components: capacitors, resistors, and crucially, diodes and transistors. Transistors are particularly complex structures, requiring delicately patterned films of a semiconductor like silicon doped with other elements and sandwiched with metal electrodes and insulating layers. Using silicon membranes, along with magnesium and its oxide, Rogers’ team made versions that dissolve within hours.

One of the first full circuits that they have made is an RF “power scavenger”, which can convert up to 15% of the radio waves it absorbs at a particular frequency into electrical power. Their prototype, measuring about 10cm (4in) by 4cm (1.6 in), can pick up enough power to run a small commercial light-emitting diode. The team can control the rate at which these devices dissolve by fine-tuning the molecular structure of the silk sheets on which they are laid down or between which they are sandwiched. This way, they can make devices that last for a week or two – about the length of time needed to ward off bacteria from a healing wound.

As well as deterring bacteria, Rogers says that implantable, bio-absorbable RF electronics could be used to stimulate nerves for pain relief, and to stimulate bone re-growth, a process long proven to work when electrodes are placed on the skin or directly on the bone. Conceivably they could also be used to precisely control drug release from implanted reservoirs.

Source: BBC

Digital camera gives a bug’s-eye view.


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Insect-inspired device achieves panoramic view and sharp focus at any distance.

Insects have a wide field of view and are acutely sensitive to motion, as anyone who has tried chasing a housefly knows. Researchers have now created a digital camera that mimics the curved, compound structure of an insect eye. These cameras could be used where wide viewing angles are important and space is at a premium — in advanced surveillance systems, for example, or in unmanned flying vehicles and endoscopes.

Insect eyes are made up of hundreds or even thousands of light-sensing structures called ommatidia. Each contains a lens and a cone that funnels light to a photosensitive organ. The long, thin ommatidia are bunched together to form the hemispherical eye, with each ommatidium pointing in a slightly different direction. This structure gives bugs a wide field of view, with objects in the periphery just as clear as those in the centre of the visual field, and high motion sensitivity. It also allows a large depth of field — objects are in focus whether they’re nearby or at a distance.

The biggest challenge in mimicking the structure of an insect eye in a camera is that electronics are typically flat and rigid, says John Rogers, a materials scientist at the University of Illinois at Urbana-Champaign. “In biology, everything is curvy,” he says.

The new device, which Rogers and his colleagues describe today in Nature1, comprises an array of microlenses connected to posts that mimic the light-funnelling cones of ommatidia, layered on top of a flexible array of silicon photodetectors. The lens–post pairs are moulded from a stretchy polymer called an elastomer. A filling of elastomer dyed with carbon black surrounds the structures, preventing light from leaking between them. The lens is about 1 centimetre in diameter.

“The whole thing is stretchy and thin, and we blow it up like a balloon” so that it curves like a compound eye, says Rogers. The current prototype produces black-and-white images only, but Rogers says a colour version could be made with the same design.

This is the first time researchers have made a working compound-eye camera, says Luke Lee, a bioengineer at the University of California, Berkeley, who was not involved with the work. The trick, he says, was building and integrating all the parts of the ommatidia. “Usually people just show one part, the lens or the detector,” says Lee. In 2006, for example, Lee’s group made arrays of artificial ommatidia that had microlenses and light-guiding cones, but no photodetectors2.

He says that Rogers made the device work by predicting the mechanics of how his designs would stretch before building them — to make sure that the lenses would not be distorted when the device was inflated, for example.

Rogers describes the camera as a “low-end insect eye”. It contains 180 artificial ommatidia, about the same number as in the eyes of a fire ant (Solenopsis fugax) or a bark beetle (Hylastes nigrinus) — insects that don’t see very well. So far the researchers have tested it by taking pictures of simple line drawings (see image).

With the basic designs in place, Rogers says, his team can now increase the resolution of the camera by incorporating more ommatidia. “We’d like to do a dragonfly, with 20,000 ommatidia,” he says, which will require some miniaturization of the components.

Alexander Borst, who builds miniature flying robots at the Max Planck Institute of Neurobiology in Martinsried, Germany, says that he is eager to integrate the camera into his machines. Insects’ wide field of vision helps them to monitor and stabilize their position during flight; robots with artificial compound eyes might be better fliers, he says.

Rogers says that his next project is to go “beyond biology”, by inflating or deflating the camera to adjust its field of view.

Source: nature