October 20, 2010, 7:03 AM CT

Sensor derived from frogs

Princeton engineers have developed a sensor that may revolutionize how drugs and medical devices are tested for contamination, and in the process also help ensure the survival of two species of threatened animals.

To be fair, some of the credit goes to an African frog.

In the wild, the African clawed frog produces antibacterial peptides -- small chains of amino acids -- on its skin to protect it from infection. Princeton scientists have found a way to attach these peptides, which can be synthesized in the laboratory, to a small electronic chip that emits an electrical signal when exposed to harmful bacteria, including pathogenic E. coli and salmonella.

"It's a robust, simple platform," said Michael McAlpine, an assistant professor of mechanical and aerospace engineering and the lead researcher on the project. "We think these chips could replace the current method of testing medical devices and drugs".

A paper outlining their development of the sensor was published online October 18 in the Proceedings of the National Academy of Science The research was funded by the American Asthma Foundation and by the Air Force Office of Scientific Research.

The current testing method has a major drawback: It relies on the blood of the horseshoe crab, a species that is roughly 450 million years old. The horseshoe crab population has declined in recent years, and as a result, so too has the population of a bird that feasts on the crab......... Posted by: Kelly      Read more         Source

October 15, 2010, 6:38 AM CT

Humidity makes gecko feet stickier

Human adhesives are famed for their fallibility. Gooey glues soon lose their grip, are easily contaminated and leave residues behind. But not gecko feet. Geckos can cling on repeatedly to the smoothest surfaces thanks to the self-cleaning microscopic spatula-shaped hairs (setae) that coat the soles of their feet. Back in 2002, Kellar Autumn observed that these dry hairs are in such intimate contact with surfaces that the reptiles 'glue' themselves on by van der Waals forces with no need for fluid adhesives. More recent studies had suggested that geckos might benefit from additional adhesion in humid environments through capillary action provided by microscopic droplets of water sandwiched between setae and the surface. But Autumn wasn't so sure, so he and his lab at Lewis and Clark College and the University of Washington, USA, began testing gecko grip to find out how increasing humidity helps them hold tight Autumn publishes his team's discovery that humidity helps geckos grip tighter by softening the surface of their feet on 15 October 2010 in The Journal of Experimental Biology at http://jeb.biologists.org.

Knowing that geckos replace lost setae when they moult, Autumn, his postdoc Jonathan Puthoff, and Matt Wilkinson collected patches of the 'sticky' hairs from gecko feet and attached them to a mechanical testing device, known as 'Robotoe', that reproduces the way the reptile drags its foot as it contacts a surface. Dragging the setae across two surfaces (one that repelled water and another that attracted water) at different velocities and in environments ranging from 10% to 80% humidity, the team tested whether microscopic water bridges formed in high humidity were helping the geckos hang on. They reasoned that if the reptiles were using microscopic water bridges then the setae would bond more tightly to the surface that attracted water than the surface that repelled water. But when they measured the setae's adhesion and friction it was essentially the same on the two surfaces. And when the team compared the adhesion of setae that were moving too fast to form water bridges with that of slowly moving feet that could possibly form water bridges, there was no difference. The geckos were not supplementing their van der Waals attachment forces with capillary forces from water bridges. So how were they holding on tighter?........ Posted by: Kelly      Read more         Source

October 11, 2010, 7:57 AM CT

Plants kick-start evolutionary drama

An international team of scientists, exploiting pioneering techniques at Arizona State University, has taken a significant step toward unlocking the secrets of oxygenation of the Earth's oceans and atmosphere.

Evolution of the Earth's multitude of organisms is intimately associated with the rise of oxygen in the oceans and atmosphere. The new research indicates that the appearance of large predatory fish as well as vascular plants approximately 400 million years ago coincided with an increase in oxygen, to levels comparable to those we experience today. If so, then animals from before that time appeared and evolved under markedly lower oxygen conditions than previously thought.

The researchers, including collaborators from Harvard, Denmark, Sweden and the United Kingdom, made use of a method developed at ASU by Ariel Anbar, a professor in the department of chemistry and biochemistry and the School of Earth and Space Exploration in the College of Liberal Arts and Sciences, and his research group. The method can be used to estimate global oxygen levels in ancient oceans from the chemical composition of ancient seafloor sediments.

Their important findings are presented in a paper published in this week's online Early Edition of the Proceedings of the National Academy of Sciences (PNAS), titled "Devonian rise in atmospheric oxygen corcorrelation to radiations of terrestrial plants and large predatory fish"......... Posted by: Kelly      Read more         Source

October 11, 2010, 7:32 AM CT

Freely Swimming Microorganisms

Two separate research groups are reporting groundbreaking measurements of the fluid flow that surrounds freely swimming microorganisms. Experiments involving two common types of microbes reveal the ways that one creature's motion can affect its neighbors, which in turn can lead to collective motions of microorganism swarms. In addition, the research is helping to clarify how the motions of microscopic swimmers produces large scale stirring that distributes nutrients, oxygen and chemicals in lakes and oceans. A pair of papers describing the experiments will appear in the October 11 issue of the APS journal Physical Review Letters.

In order to observe the flow that microorganisms produce, scientists at the University of Cambridge tracked the motion of tiny tracer beads suspended in the fluid surrounding the tiny swimmers. They used the technique to study the fluid around two very different types of creatures: a small, blue-green form of algae called Chlamydomonas reinhardtii that swims by paddling with a pair of whip-like flagella, and the larger, spherical alga Volvox carterii that propels itself with thousands of flagella covering its surface. The tracer beads showed that the two types of organisms generate distinctly different flow patterns, both of which are much more complex than previously assumed. In a related study performed at Haverford College in Pennsylvania, scientists used a high speed camera to track the flow of tracer particles around Chlamydomonas in a thin, two-dimension film of fluid over the course of a single stroke of its flagella......... Posted by: Janet      Read more         Source

October 11, 2010, 7:28 AM CT

Monarch butterflies use medicinal plants

Monarch butterflies appear to use medicinal plants to treat their offspring for disease, research by biologists at Emory University shows. Their findings were published online Oct. 6 in the journal Ecology Letters.

"We have shown that some species of milkweed, the larva's food plants, can reduce parasite infection in the monarchs," says Jaap de Roode, the evolutionary biologist who led the study. "And we have also observed that infected female butterflies prefer to lay their eggs on plants that will make their offspring less sick, suggesting that monarchs have evolved the ability to medicate their offspring." (See interview with de Roode here: http://tinyurl.com/3995m3u).

Few studies have been done on self-medicine by animals, but some researchers have theorized that the practice appears to be more widespread than we realize. "We think that our experiments provide the best evidence to date that animals use medication," de Roode says.

"The results are also exciting because the behavior is trans-generational," says Thierry Lefevre, a post-doctoral fellow in de Roode's lab. "While the mother is expressing the behavior, only her offspring benefit. That finding is surprising for monarch butterflies".

The findings also may have implications for human health, says University of Michigan chemical ecologist Mark Hunter, who collaborated with de Roode's group on the research......... Posted by: Kelly      Read more         Source

October 8, 2010, 7:43 AM CT

Scientists Trick Bacteria with Small Molecules

A team of Yale University researchers has engineered the cell wall of the Staphylococcus aureus bacteria, tricking it into incorporating foreign small molecules and embedding them within the cell wall.

The finding, described online in the journal ACS Chemical Biology this week, represents the first time researchers have engineered the cell wall of a pathogenic "Gram-positive" bacteria-organisms responsible not only for Staph infections but also pneumonia, strep throat and a number of others. The discovery could pave the way for new methods of combating the bacteria responsible for a number of of the most infectious diseases.

The team engineered one end of their small molecules to contain a peptide sequence that would be recognized by the bacteria. In Staphylococcus aureus, an enzyme called sortase A is responsible for attaching proteins to the cell wall.

"We sort of tricked the bacteria into incorporating something into its cell wall that it didn't actually make," said David Spiegel, a Yale chemist who led the study. "It's as if the cell thought the molecules were its own proteins rather than recognizing them as something foreign".

The researchers focused specifically on the cell wall because it contains a number of of the components the cell uses to relate to its environment, Spiegel said. "By being able to manipulate the cell wall, we can in theory perturb the bacteria's ability to interact with human tissues and host cells"......... Posted by: Janet      Read more         Source

October 8, 2010, 6:07 AM CT

Turtle, Dugongs 'at Risk Under Climate Change'

The "turtle and dugong capital of the world", the northern Great Barrier Reef (GBR) and Torres Strait region, faces increased pressure under climate change from human actions such as fishing, hunting, onshore development and pollution.

"Depletion of turtle and dugong numbers increases their vulnerability to other threats and lowers their ability to cope with climate change," Dr Mariana Fuentes of the ARC Centre of Excellence for Coral Reef Studies and James Cook University will tell the Coral Reef Symposium in Canberra today.

Dr Fuentes says that turtles in particular are vulnerable to the effects of climate change, which include decreases in hatching success, loss of nesting areas and overheated beaches, which will decrease the turtles' reproductive output and may significantly alter the sex ratio of their offspring.

Dr. Fuentes' research into the green, hawksbill and flatback turtles and well as dugongs in the northern GBR and Torres Strait is seeking to establish priorities for the management of marine megafauna to increase their resilience to climate change.

"Managers face the challenge of addressing the direct effects of climate change, as well as ongoing threats that dugongs and sea turtles face throughout their geographic range," she explains. "For logistical, financial and political reasons, managers cannot address all threats simultaneously, and so need to prioritize their actions......... Posted by: Kelly      Read more         Source

October 5, 2010, 7:30 AM CT

Powerful supercomputer peers into the origin of life

Supercomputer simulations at the Department of Energy's Oak Ridge National Laboratory are helping researchers unravel how nucleic acids could have contributed to the origins of life.

A research team led by Jeremy Smith, who directs ORNL's Center for Molecular Biophysics and holds a Governor's Chair at University of Tennessee, used molecular dynamics simulation to probe an organic chemical reaction that may have been important in the evolution of ribonucleic acids, or RNA, into early life forms.

Certain types of RNA called ribozymes are capable of both storing genetic information and catalyzing chemical reactions - two necessary features in the formation of life. The research team looked at a lab-grown ribozyme that catalyzes the Diels-Alder reaction, which has broad applications in organic chemistry.

"Life means making molecules that reproduce themselves, and it requires molecules and are sufficiently complex to do so," Smith said. "If a ribozyme like the Diels-Alderase is capable of doing organic chemistry to build up complex molecules, then potentially something like that could have been present to create the building blocks of life."

The research team found a theoretical explanation for why the Diels-Alder ribozyme needs magnesium to function. Computational models of the ribozyme's internal motions allowed the scientists to capture and understand the finer details of the fast-paced reaction. The static nature of conventional experimental techniques such as chemical probing and X-ray analysis had not been able to reveal the dynamics of the system......... Posted by: Kelly      Read more         Source

October 5, 2010, 7:28 AM CT

A decade of discovery for marine life

The Census of Marine Life, a ten-year initiative to describe the distribution and diversity of ocean life, draws to a close today with a celebration, symposium and press conference in London. At the press conference, researchers revealed the results of the census, including the discovery of new species, new patterns of biodiversity and more. Researchers at the University of Alaska Fairbanks have played a major role in what the census calls its "decade of discovery".

UAF researchers have led two multi-year projects as part of the census. Both projectsthe Arctic Ocean Diversity project and the Natural Geography in Shore Areas projectare dedicated to explaining the biodiversity of different areas in the world's ocean. Between them, the projects identified dozens of new species and cataloged nearshore organisms at more than 200 sites worldwide.

The Arctic Ocean Diversity project, also called ArcOD, is an international effort to identify the number and variety of marine creatures living in the Arctic. The project looks at organisms that live in arctic sea ice, the water column and on the seafloor, from microscopic plankton to fishes and birds.

Bodil Bluhm, associate professor of marine biology, Rolf Gradinger, associate professor of oceanography, and Russ Hopcroft, professor of oceanography, are leading the project......... Posted by: Kelly      Read more         Source

October 3, 2010, 9:09 PM CT

Ireland's smooth-hound sharks

They grow to over a meter in length, can weigh up to twelve kilos and each summer they swarm into the shallow waters of the Irish east coast. Despite this, the starry smooth-hound has remained Ireland's least well known shark species. However, thanks to scientists at University College Dublin, whose work is now reported in the Journal of Fish Biology, this appears to be about to change.

Dr. Edward Farrell, who recently graduated from UCD School of Biology & Environmental Science, spent the last four years studying these unusual sharks. Under the supervision of Dr. Stefano Mariani of the SBES and Dr. Maurice Clarke of the Marine Institute, the PhD project successfully investigated the age, growth, reproduction and identification of the species in the Northeast Atlantic.

"It's amazing how little was known about this species considering their size and abundance on the east coast," said Farrell. "Until recently we weren't even sure what species we were dealing with but we developed a genetic method which allowed us to confirm that it is the starry smooth-hound which occurs in Irish waters and not the related common smooth-hound. Once this was established we were able to investigate their life-history".

Starry smooth-hounds were previously considered to be a fast growing and early maturing species, meaning they were not a conservation concern. However the results of the four year project have revealed that starry smooth-hounds in Irish waters actually grow twice as slowly as previously estimated and only reproduce every two years rather than annually as is the case in the Mediterranean......... Posted by: Kelly      Read more         Source