October 9, 2008, 10:31 PM CT

What causes cellular defences to crumble

Mussels possess a cellular barrier against toxicants that can be breached by environmental chemicals.

German and American scientists have for the first time identified complete gene sequences and function of two proteins in mussels that play a key defensive role against environmental toxicants. These proteins form part of an active, physiological barrier in mussel gills that protects them against environmental toxicants, scientists from the Helmholtz Centre for Environmental Research (UFZ) and Stanford University in California report in the American Journal of Physiology - Regulatory, Integrative and Comparative Physiology. Mussels like the California mussel (Mytilus californianus) can pump over 20 litres of water through their gills every hour. The active barrier protects the organism against harmful substances in the water. The presence of such proteins in mussel gills has been previously indicated, but it is only now that they can be accurately identified. The function of these proteins can be inhibited by chemicals introduced into the environment by humans, e.g. galaxolide, a perfume used in cleaning products. This means that such substances open the way for other chemicals to enter cells. Even chemicals that are not regarded as toxic by conventional standards can enhance toxicity of other compounds. Little is known about the global environmental and human impacts of these 'chemosensitizers'......... Posted by: Janet      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

October 2, 2008, 10:30 PM CT

A molecule that coordinates the movement of cells

Even cells commute. To get from their birthplace to their work site, they sequentially attach to and detach from an elaborate track of exceptionally strong proteins known as the extracellular matrix. Now, in research to appear in the October 3 issue of Cell, researchers at the Howard Hughes Medical Institute and Rockefeller University show that a molecule, called ACF7, helps regulate and power this movement from the inside - findings that could have implications for understanding how cancer cells metastasize.

"The most dangerous part of cancer is that cancer cells migrate from their primary location and invade other parts of the body," says first author Xiaoyang Wu, a postdoc in Elaine Fuchs's Laboratory of Mammalian Cell Biology and Development. "ACF7 facilitates cell movement, so it's possible that the less ACF7 a cell has, the less cancerous it would become. It's a really exciting question in cancer biology now".

To travel along the extracellular matrix, cells must stick to and unstick from it via focal adhesions, structures composed of molecules that connect the inside to the outside of the cell. (While some molecules connect to the matrix, others connect to a scaffold inside the cell called the cytoskeleton.) As these structures collectively assemble and disassemble, the cell walks forward. Fuchs and Wu show that ACF7 can not only access energy stores to power this movement from within but also coordinate it by linking two fiber-like proteins called f-actin and microtubules, which together form the cytoskeleton and help give cells their shape......... Posted by: Janet      Read more         Source

October 2, 2008, 5:08 AM CT

Structures of Important Plant Viruses Determined

Flexible filamentous viruses make up a large fraction of known plant viruses and are responsible for more than half the viral damage to crop plants throughout the world. New details of their structures, which were poorly understood, have been revealed by researchers using a variety of sophisticated imaging techniques at the U.S. Department of Energy's Brookhaven National Laboratory and collaborating institutions.

These findings, just reported in the October 1, 2008, issue of the Journal of Virology, may lead to new ways to protect crop plants from viruses and other forms of damage. The structural information may also benefit researchers interested in using viruses as agents of biotechnology to coax plants to produce other useful products, such as pharmaceuticals.

"These are very important viruses, and we knew almost nothing about their detailed structure before these studies," said Gerald Stubbs, a structural biologist at Vanderbilt University and lead author on the paper. "If you are to come up with any molecular way of combating these plant diseases, you need to know the details of their structures." For example, structural information could help researchers design molecules that interfere with the virus's ability to infect plant cells.

The researchers from Vanderbilt, Brookhaven, Boston University, Illinois Institute of Technology, and the University of Kentucky studied the structures of two plant viruses from unrelated families, the Potyviridae and Flexiviridae, using a combination of complementary imaging techniques - x-ray diffraction at DOE's Argonne National Laboratory, cryo-electron microscopy at Vanderbilt, and scanning transmission electron microscopy (STEM) at Brookhaven......... Posted by: Erica      Read more         Source

October 1, 2008, 8:30 AM CT

Green coffee-growing practices buffer climate-change impacts

Chalk up another environmental benefit for shade-grown Latin American coffee: University of Michigan scientists say the technique will provide a buffer against the ravages of climate change in the coming decades.

Over the last three decades, a number of Latin American coffee farmers have abandoned traditional shade-growing techniques, in which the plants are grown beneath a diverse canopy of trees. In an effort to increase production, much of the acreage has been converted to "sun coffee," which involves thinning or removing the canopy.

Shade-grown farms boost biodiversity by providing a haven for birds and other animals. They also require far less synthetic fertilizer, pesticides and herbicides than sun-coffee plantations.

In the October edition of the journal BioScience, three U-M scientists say shade-growing also shields coffee plants during extreme weather events, such as droughts and severe storms. Climate models predict that extreme weather events will become increasingly common in the coming decades, as the levels of heat-trapping carbon dioxide gas continue to mount.

The U-M researchers warn Latin American farmers of the risks tied to "coffee-intensification programs"---a package of technologies that includes the thinning of canopies and the use of high-yield coffee strains that grow best in direct sunlight---and urge them to consider the greener alternative: shade-grown coffee......... Posted by: Erica      Read more         Source

September 29, 2008, 10:33 PM CT

Self-training gene prediction program for fungi

Scientists at the Georgia Institute of Technology have developed a computer program that trains itself to predict genes in the DNA sequences of fungi.

Fungi which range from yeast to mushrooms are important for industry and human health, so understanding the recently sequenced fungal genomes can help in developing and producing critical pharmaceuticals. Gene prediction can also help to identify potential targets for therapeutic intervention and vaccination against pathogenic fungi.

"While we previously showed that our unsupervised training program worked well to predict genes in a number of eukaryotes, it didn't work as well for various fungal genomes that carry a significant part of the information that facilitates accurate gene prediction in locations called branch point sites," said Mark Borodovsky, director of Georgia Tech's Center for Bioinformatics and Computational Genomics.

Branch point sites are located inside introns, which are non-coding regions of DNA located between genetic-code carrying regions called exons.

"Previously during the process of predicting the exon-intron structure of eukaryotic genes, we didn't search for branch point sites, but doing so in the new program helps to better delineate intron regions inside fungal genes," added Borodovsky, who is also a Regents' Professor in the Coulter Department of Biomedical Engineering and the Computational Science and Engineering Division of the College of Computing......... Posted by: Janet      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