October 15, 2008, 5:28 PM CT

As Sticky as a Gecko, but Ten Times Stronger!

The gecko's amazing ability to stick to surfaces and walk up walls has inspired a number of scientists to manufacture materials that mimic the special surface of a gecko's foot. The secret behind the gecko's ability to stick so well is a forest of pillars at the micro-/nano-scale on the underside of the gecko's foot. Because there are so a number of pillars so close together, they are held tightly to the surface the gecko is walking on by a molecular force called the Van der Waals force. This relatively weak force causes uncharged molecules to attract each other.

In an unprecedented feat, Liming Dai, at the University of Dayton, and his colleagues report in the October 10th issue of Science successful construction of a gecko-inspired adhesive that is ten times stronger than a gecko, at about 100 newtons per square centimeter.

The scientists constructed their adhesive out of two slightly different layers of multi-walled carbon nanotubes. The lower layer is composed of vertically-aligned carbon nanotubes, while the upper segment--which comes into contact with the surface it is sticking to--is curly, like a mess of spaghetti.

As shown in the figure, the adhesive sticks best when it is pulled down parallel to the surface it is sticking to--this is called shear adhesion. This action arranges the tips of the curly nanotubes so they have maximum contact with the substrate, thereby maximizing the Van der Waals force. Pulling the adhesive off in a motion perpendicular to the substrate is much easier--at this angle the sticking force is ten times weaker......... Posted by: Kelly      Read more         Source

October 15, 2008, 5:25 PM CT

Evolutionary Transition from Fish to Land Animals

New research has provided the first detailed look at the internal head skeleton of Tiktaalik roseae, the 375-million-year-old fossil animal that represents an important intermediate step in the evolutionary transition from fish to animals that walked on land.

Results of the study, published in this week's issue of the journal Nature, show that the transition from aquatic to terrestrial lifestyle involved complex changes not only to appendages (fins to limbs) but also to the internal head skeleton.

"Exquisite specimens of Tiktaalik roseae discovered several years ago continue to function as rosetta stones for understanding the emergence of quadripeds on land," said H. Richard Lane, program director in the National Science Foundation (NSF)'s Division of Earth Sciences, which funded the research.

A team co-led by scientist Ted Daeschler at the Academy of Natural Sciences in Philadelphia discovered Tiktaalik roseae (tik-TAHL-ik RO-zay) in 2004, in Devonian-age rock on Ellesmere Island in Canada, more than 700 miles above the Arctic Circle.

The creature was a large aquatic predator with a flattened head and body.

The body plan and nature of the deposits where the fossils were found suggest an animal that lived on the bottom in shallow water, and perhaps out of the water for short periods......... Posted by: Kelly      Read more         Source

October 12, 2008, 6:17 PM CT

Fitness in a Changing World

The stickleback fish, Gasterosteus aculeatus, is one of the most thoroughly studied organisms in the wild, and has been a especially useful model for understanding variation in physiology, behavior, life history and morphology caused by different ecological situations in the wild.

On biological levels from molecular and genetic to developmental and morphological, and finally ending with the population level, it has proven far more complex than even imagined.

Studies of stickleback have provided us with a much better understanding of how organisms cope with new environmental conditions, first through acclimation over an individual's lifespan, and subsequently through adaptation of population via changes in gene form (allele) frequencies.

Given the rapidly changing global environment, this research not only provides insight into evolutionary processes, but is of practical importance in understanding how organisms will adapt to a changing world.

There are two forms of the stickleback: the oceanic and the freshwater type. The oceanic form lives in the ocean and comes into shallow estuarine or freshwater rivers and streams to breed, and has repeatedly given rise to a freshwater form that lives its entire life isolated in freshwater habitats......... Posted by: Kelly      Read more         Source

October 9, 2008, 10:45 PM CT

Digital zebrafish embryo provides blueprint of a vertebrate

Scientists at the European Molecular Biology Laboratory (EMBL) have generated a digital zebrafish embryo - the first complete developmental blueprint of a vertebrate. With a newly developed microscope researchers could for the first time track all cells for the first 24 hours in the life of a zebrafish. The data was reconstructed into a three-dimensional, digital representation of the embryo. The study, reported in the current online issue of Science, grants a number of new insights into embryonic development. Movies of the digital embryo and the underlying database of millions of cell positions, divisions and tracks will be made publicly available to provide a novel resource for research and scientific training.

To get from one cell to a complex organism, cells have to divide, travel around the body and arrange intricate shapes and specialized tissues. The best way to understand these dynamic processes is to look at what happens in the first few hours of life in every part of an embryo. While this is possible with invertebrates with a few hundred cells, like worms for example, it has so far been impossible to achieve for vertebrates.

"Imagine following all inhabitants of a town over the course of one day using a telescope in space. This comes close to tracking the 10 thousands of cells that make up a vertebrate embryo only that the cells move in three dimensions," says Philipp Keller. Together with Annette Schmidt he carried out the research in the labs of Jochen Wittbrodt and Ernst Stelzer at EMBL......... Posted by: Kelly      Read more         Source

October 8, 2008, 9:54 PM CT

Beetles Get by With a Little Help

Humans living in communities often rely on friends to help get what they need and, as per scientists in the lab of Cameron Currie at the University of Wisconsin-Madison, a number of microbes, plants and animals benefit from 'friendly' associations too.

The Currie team's study, which was funded by the National Science Foundation (NSF) and reported in the Oct. 3, 2008, issue of the journal Science, describes the complex relationship between a beetle, two types of tree fungus and a bacterium that aids in their struggle to survive and thrive.

Research in the Currie lab revealed that adult beetles have a specialized compartment in their bodies used to store two other organisms: a slow-growing beneficial fungus that serves as a food source and a bacterium that produces a unique, newly discovered antibiotic. Interestingly, the antibiotic inhibits the growth of a fast-growing competitor fungus but does not affect the slow-growing beneficial fungus.

Before laying eggs in tree bark, adult female beetles spread the slow-growing, beneficial fungus and bacteria around the area where they will deposit the eggs. The antibiotic from the bacteria prevents growth of the fast-growing competitor fungus but does not harm the slow-growing beneficial fungus, which continues to grow and provide a rich source of nutrition for the developing beetle larvae......... Posted by: Kelly      Read more         Source

October 8, 2008, 9:40 PM CT

Beavers: Dam good for songbirds

The songbird has a friend in the beaver. As per a research studyby the Wildlife Conservation Society (WCS), the busy beaver's signature dams provide critical habitat for a variety of migratory songbirds, especially in the semi-arid interior of the West.

The study, which appears in the October 2008 issue of the journal Western North American Naturalist, says that through dam building, beavers create ponds and stimulate growth of diverse streamside vegetation critical for birds, including a number of migratory songbirds in decline. The study observed that the more dams beavers build, the more abundant and diverse local songbirds become.

"We observed that increasing density of beaver dams was linked to a diverse and abundant bird community and the wetland and streamside habitat these species depend on," said Hilary Cooke, the study's lead author who is now finishing her dissertation at the University of Alberta in Edmonton. "This habitat is critical to birds in semi-arid regions yet has been severely degraded or lost through much of the West. Our results suggest that management of beavers may be an important tool for restoring habitat and reversing bird declines."

Beaver populations once numbered in the millions in the American West but dramatically collapsed due to the fur trade in the 1800s. Currently, beaver are often considered a pest species when they take down trees and flood property. Their influence is still missing on most watersheds in the West, yet this and other studies suggest that beaver are very important to wildlife and to reviving the natural function of streams......... Posted by: Kelly      Read more         Source

October 2, 2008, 10:45 PM CT

Models of eel cells suggest electrifying possibilities

Engineers long have known that great ideas can be lifted from Mother Nature, but a new paper* by scientists at Yale University and the National Institute of Standards and Technology (NIST) takes it to a cellular level. Applying modern engineering design tools to one of the basic units of life, they argue that artificial cells could be built that not only replicate the electrical behavior of electric eel cells but in fact improve on them. Artificial versions of the eels electricity generating cells could be developed as a power source for medical implants and other tiny devices, they say.

The paper, as per NIST engineer David LaVan, is an example of the relatively new field of systems biology. Do we understand how a cell produces electricity well enough to design oneand to optimize that design? he asks.

Electric eels channel the output of thousands of specialized cells called electrocytes to generate electric potentials of up to 600 volts, as per biologists. The mechanism is similar to nerve cells. The arrival of a chemical signal triggers the opening of highly selective channels in a cell membrane causing sodium ions to flow in and potassium ions to flow out. The ion swap increases the voltage across the membrane, which causes even more channels to open. Past a certain point the process becomes self-perpetuating, resulting in an electric pulse traveling through the cell. The channels then close and alternate paths open to pump the ions back to their initial concentrations during a resting state......... Posted by: Kelly      Read more         Source

October 2, 2008, 10:40 PM CT

Beetles get by with a little help from their friends

Humans living in communities often rely on friends to help get what they need and, as per scientists in the lab of Cameron Currie at the University of Wisconsin-Madison, a number of microbes, plants and animals benefit from 'friendly' associations too.

The Currie team's study, which was funded by the National Science Foundation (NSF) and reported in the Oct. 3, 2008, issue of the journal Science, describes the complex relationship between a beetle, two types of tree fungus and a bacterium that aids in their struggle to survive and thrive.

Research in the Currie lab revealed that adult beetles have a specialized compartment in their bodies used to store two other organisms: a slow-growing beneficial fungus that serves as a food source and a bacterium that produces a unique, newly discovered antibiotic. Interestingly, the antibiotic inhibits the growth of a fast-growing competitor fungus but does not affect the slow-growing beneficial fungus.

Before laying eggs in tree bark, adult female beetles spread the slow-growing, beneficial fungus and bacteria around the area where they will deposit the eggs. The antibiotic from the bacteria prevents growth of the fast-growing competitor fungus but does not harm the slow-growing beneficial fungus, which continues to grow and provide a rich source of nutrition for the developing beetle larvae......... Posted by: Kelly      Read more         Source

September 29, 2008, 10:27 PM CT

Common insecticide can decimate tadpole populations

The latest findings of a University of Pittsburgh-based project to determine the environmental impact of routine pesticide use suggests that malathionthe most popular insecticide in the United Statescan decimate tadpole populations by altering their food chain, as per research reported in the Oct. 1 edition of Ecological Applications.

Gradual amounts of malathion that were too small to directly kill developing leopard frog tadpoles instead sparked a biological chain of events that deprived them of their primary food source. As a result, nearly half the tadpoles in the experiment did not reach maturity and would have died in nature. The research was funded by a National Science Foundation grant.

The results build on a nine-year effort by study author Rick Relyea, an associate professor of biological sciences in Pitt's School of Arts and Sciences, to investigate whether there is a link between pesticides and the global decline in amphibians, which are considered an environmental indicator species because of their sensitivity to pollutants. Their deaths may foreshadow the poisoning of other, less environmentally sensitive speciesincluding humans. Relyea published papers in 2005 in Ecological Applications suggesting that the popular weed-killer Roundup is "extremely lethal" to amphibians in concentrations found in the environment......... Posted by: Kelly      Read more         Source

September 18, 2008, 9:18 PM CT

Coating copies microscopic biological surfaces

Someday, your car might have the metallic finish of some insects or the deep black of a butterfly's wing, and the reflectors might be patterned on the nanostructure of a fly's eyes, as per Penn State scientists who have developed a method to rapidly and inexpensively copy biological surface structures.

"Only a small fraction of mutations in evolutionary processes are successful," said Akhlesh Lakhtakia, the Charles Godfrey Binder (Endowed) Professor of Engineering Science and Mechanics. "But evolution has gone on for at least a billion years. A huge range of biological surface architectures have been created and are available".

Lakhtakia and colleagues, Carlo G. Pantano, distinguished professor of materials science and engineering, and director of Penn State's Materials Research Institute, and Raúl J. Martín-Palma, visiting professor, Penn State, and professor department of applied physics, Universidad Autonomia de Madrid, used the conformal evaporated film by rotation (CEFR) technique to produce coatings that capture the micro- and nanostructure of biological surfaces in a thin coating of glass. The results appear in recent issues of Applied Physics Letters and Nanotechnology.

In the CEFR technique, the scientists thermally evaporate the material that forms the coating in a vacuum chamber. The object receiving the coating is fixed to a holder and rotated about once every two seconds. The scientists have coated butterfly wings and a fly, creating replicas of these templates with identical surface characteristics. The scientists are using chalcogenide glasses composed of varying combinations of germanium, antimony and selenium......... Posted by: Kelly      Read more         Source