January 8, 2006, 12:09 AM CT

Fallen Leaves Play a Role in the Food Chain

The watery plants form the base of the food chain. Energy these watery plants create supports, of the invertebrates to largest fish of sport. Now, a study proves that the watery plants receive assistance from the trees. In a recent issue of the journal Nature, Michael Pace and Jonathan Cole of the Institute of Ecosystem Studies in Millbrook, New York, along with colleagues from Wisconsin and Sweden, indicate that the terrestrial organic matter, which starts on the shore, supports a significant part of the watery food chain.

A building block of life, organic carbon is essential to aquatic food webs. In lakes, aquatic plants produce organic carbon by harnessing the sun's energy (photosynthesis); some of this carbon supports the growth of fish and invertebrate populations. Researchers have long suspected that organic carbon from land is also significant to aquatic life, but the idea is difficult to demonstrate. By tracing the fate of carbon through large-scale lake manipulations, Pace, Cole, and their colleagues have revealed that in some waters terrestrial organic carbon significantly subsidizes the aquatic food web.

"These researchers have found an ingenious method of teasing apart the carbon cycle of lakes," says James Morris, program director in the National Science Foundation (NSF)'s division of environmental biology, which funded the research. "Their study reveals a surprising degree of dependence of lake food webs on sources of organic matter transported into the lakes from the surrounding watershed. These findings reinforce the concept that the ecology of lake ecosystems is tightly coupled with that of the surrounding terrestrial landscape".........

Posted by: Ashley      Permalink


January 8, 2006, 11:26 AM CT

Secrets of Nature's Super Glue

The researchers discovered that sea water iron is the principal binder in the superb-extremely common adhesive of the mussel blue, Mytilus edulis. It is the first time that the researchers determined that a metal such as iron is critical to form an amorphous and biological material.

In more of employing knowledge to develop surer solutions of replacement for surgical and the household gluess, the researchers look at how to fight the adhesive to prevent damage with the ships and the accidental transport of the species invahissantes, such that moulds it of zebra which ravarge the middle-west region of the United States.

National Science Foundation CAREER awardee Jonathan Wilker, Mary Sever and their colleagues at Purdue University announce their discovery in the Jan. 12 issue of Angewandte Chemie.

En route to crafting synthetic versions of the glue, the scientists discovered that bivalves extract the metal iron from the surrounding seawater and use it to join proteins together, linking the fibrous molecules into a strong, adhesive mesh. The 800 mussels in Wilker's laboratory have an uncanny ability to stick to almost anything, even Teflonandreg;.

Comment from Wilker regarding research:

"Mussel glues present the first identified case in which transition metals are essential to the formation of a non-crystalline biological material," says NSF CAREER awardee Jonathan Wilker of Purdue University.........

Posted by: Ashley      Permalink


January 8, 2006, 11:07 AM CT

Solving Mystery Of Retrovirus Life Cycle

Studies on common baker's yeast have led to the discovery of what may be a long-sought mechanism in the life cycle of retroviruses, including the human immunodeficiency virus (HIV). Knowing the details of this step in the infection process could help pinpoint targets for new classes of drugs to fight HIV.

In the Jan. 9 issue of the journal Science, Thomas Menees and Zhi Cheng of the University of Missouri-Kansas City describe the formation of a lariat structure with the genetic material of retrovirus-like elements in baker's yeast and subsequent cutting of the lariat by a yeast enzyme. The findings reported in Science and in the December 2003 Journal of Virology are the payoff of a three-year research gamble by Menees and two postdoctoral scientists pursuing host-cell factors in retroviral infections.

In addition to filling a gap in biologists' understanding of how retroviruses replicate, it may turn out that similar lariat structures occur elsewhere in healthy cells and play previously unrecognized roles in cellular processes such as gene activation.

"The work of Menees and his collaborators fills a real void in our understanding of how retroviruses propagate and how genetic information is faithfully copied," said Patrick Dennis, program director for microbial genetics at the National Science Foundation (NSF), which supported the research. "The RNA lariat provides a plausible mechanism for a key step that has remained a mystery since the process of reverse transcription was first presented almost 35 years ago".........

Posted by: Ashley      Permalink


January 7, 2006, 4:34 PM CT

Killer of Southeastern Salt Marshes

Periwinkles, the spiral-shelled snails usually found along rocky U.S. shorelines, play a primary role in the unprecedented disappearance of salt marsh in the southeastern states, according to new research published in Science.

Based on extensive field studies, the work challenges six decades of salt marsh science. Ecologists have long thought that stressed soil - too much salt, not enough oxygen - was the main killer of this critical marine habitat.

But Brian Silliman, a Brown University research fellow and a University of Florida assistant professor, said drought-stressed soils pave the way for predatory periwinkles that spread fungal disease as they graze on cordgrass.

"Snails can transform healthy marsh to mudflats in a matter of months," said Silliman, lead author of the Science paper. "This finding represents a huge shift in the way we see salt marsh ecology. For years, researchers thought marsh die-off was simply a 'bottom-up' problem related solely to soil conditions. We found that the trouble also comes from the top down. Drought makes the marsh vulnerable, then the snails move in".

Thousands of acres of salt marsh have disappeared from South Carolina to Texas since 2000, according to several scientific studies. In Louisiana alone, more than 100,000 acres of marsh were severely damaged between June 2000 and September 2001. This drastic decline poses a serious threat to the ecology and economy of the southeastern seaboard and the Gulf Coast. Salt marshes serve as nursery grounds that support commercial fisheries, protect coastline from storm-induced floods, and filter fresh water before it flows out to sea.........

Posted by: Jessica      Permalink


January 4, 2006, 10:33 PM CT

Animal Family Tree Looking Bushy In Places

Two decades ago, with the advent of methods to look at the family relationships of different organisms by analyzing DNA, researchers envisioned it would only be a matter of time before the various family trees for plants, animals, fungi and their kin would be resolved with genetic precision.

And while molecular methods have had enormous success in ordering some branches in the tree of life - mammals, for example - and have played a critical role in refining and correcting trees constructed on the more traditional means of the appearance of organisms, the tree of animals remains fuzzy.

Now, researchers may know why this is so. Writing this week (Dec. 23, 2005) in the journal Science, a team of UW-Madison researchers led by Antonis Rokas, now of the Broad Institute of MIT and Harvard, suggests that a branch-by-branch account of animal relationships over a vast expanse of time is difficult to reconstruct because early animal evolution occurred in bunches.

"In general, we'd like to know who's related to whom, and the pattern of the branches of the tree of life," says Sean Carroll, a Howard Hughes Medical Institute investigator at UW-Madison and the senior author of the Science paper.

But 500 million years of animal history on Earth is a lot of ground to cover, Carroll laments, and now it seems that the periodic, frenetic bursts of evolution that occurred at certain times in the distant past make sorting out animal relationships - the branches on the tree - extraordinarily difficult.........

Posted by: Ashley      Permalink


December 30, 2005, 4:47 PM CT

Unravelling a rainforest food web

Is your enemy's enemy your friend? Not if you're an insect in the tropical rainforest in Belize. Researchers at Oxford University and Imperial College London investigating what happens to one species when another species with a shared natural predator disappears have found that the population of the remaining species increases.

Dr Owen Lewis in Oxford's Department of Zoology, with Dr Becky Morris and Professor Charles Godfray from Imperial College, studied different species of leaf-miner insects in Belize. Leaf-miners in the larval stage live within leaves, munching their way through the inside of the leaf as they grow. At maturity they develop into beetles, moths or flies. The larvae of leaf-miners are often preyed on by parasitoid wasps which develop inside the leaf-miner, eating it alive and eventually killing it.

The scientists removed one species of leaf-miner from experimental plots within the rainforest to see what would happen to the remaining species of leaf-miner. As they had predicted, the parasitoids decreased in number as a result of one of their food sources being taken away, and so the remaining leaf-miners increased.

'Instinctively you might expect that if you shared an enemy with another species and that species were removed, then your enemy - in this case the parasitoid - would focus on you, and your species would suffer as a result,' said Dr Lewis. 'But in fact, though that might happen in the very short term, removing a source of the parasitoid's food can in the long run decrease the number of parasitoids, to the benefit of other species.........

Posted by: Tyler      Permalink


December 30, 2005, 4:08 PM CT

Inner Working of Volcanoes

While volcanologists can see the dome of the Soufriere Hills Volcano on the island of Montserrat grow and collapse, it takes instrumentation to delve beneath the surface. Now, Penn State geologists, using tiltmeter measurements, have investigated a shallow area under the dome and what they found was not quite what they expected.

"The Soufriere Hills Volcano has been building a lava dome, collapsing and rebuilding a dome since 1995, when it first erupted," says Dr. Christina Widiwijayanti, postdoctoral researcher in geosciences, working with Dr. Barry Voight, professor of geosciences."We are working with data collected from tiltmeters in 1997 to try to understand the volcano's behavior and what is happening inside".

Voight had placed several tiltmeters around the crater rim of the volcano in 1996-97, but no more than two were ever working at once and during the important June 25, 1997 dome collapse, only one was operational. However, from a record the prior month, two tiltmeters recorded the cycle of pressurization and depressurization that took place under the dome on a 3 to 30-hour cycle.

A tiltmeter, like a carpenter's level, measures the local angular movement of the Earth. With synchronized data from two tiltmeters, the researchers, who included Dr. Amanda Clarke a former Penn State graduate student who is now an assistant professor at Arizona State University, and Dr. Derek Elsworth, professor of energy and geo-environmental engineering, could determine the depth of the source region causing the tilting near the dome. They reported their work in a January issue of Geophysical Research Letters.........

Posted by: Jaison      Permalink


December 30, 2005, 3:54 PM CT

Honeysuckle Opens Door for New Hybrid Insect Species

University Park, Pa. - The animal family tree may not be filled just with forks, but may also contain knots: hybrid species with two different ancestors rather than one, according to a team of Penn State researchers.

"We are looking for the origin of species," says Dr. Dietmar Schwarz, post-doctoral researcher in entomology. "In animals, people envision the formation of a new species by a split of one ancestral species to two derived species or a branching of one species from another".

However, according to Schwarz, another way to get a new species is for two species to hybridize - mate with each other - forming a new species lineage while the parental species persists.

"It is thought that over 50 percent of plants came into being this way, but that this mechanism played hardly any role in animals," says Schwarz. "Hybridization was seen as an accident resulting in sterile offspring like mules, but not as the beginning of a new species".

In the plant world, a number of plants create hybrid species by doubling the number of chromosomes in the parent for the offspring generation, but some hybrids, like the sunflower species, do contain the same number of chromosomes as the parents. For a handful of animal species - some fish - genetic information suggests hybridization as the most likely form of origin, but only a little is known about the actual mechanism.........

Posted by: Jaison      Permalink


December 26, 2005, 11:35 PM CT

Hidden Invaders In A Hawaiian Rain Forest

By applying novel measurement techniques from a high-altitude aircraft, researchers detected two species of invading plants that are changing the ecology of rain forest near the Kilauea Volcano in the Hawaii Volcanoes National Park. Lead author, Dr. Gregory Asner of the Carnegie Institution's Department of Global Ecology, explained: "We found chemical fingerprints from the plant leaves and used them to tell which species dominated specific areas. We employed the recently upgraded NASA Airborne Visible and Infrared Imaging Spectrometer (AVIRIS) to measure leaf nitrogen and water content from the aircraft, and corroborated the data on the ground.

The fingerprints showed where the native dominant tree 'ohia' (Metrosideros polymorpha) has been taken over by the invading Canary Islands tree, Myrica faya, and more importantly identified areas where Myrica invasion is in its early stages. The aircraft imagery also showed us how the forest canopy chemistry is changing as a result of the invader." The study is published in the March 7-11, 2005, early online edition of the Proceedings of the National Academy of Sciences.

The new methods are exciting because they detect effects of biological invasions on ecosystems, not just the presence of an invader. Islands like Hawaii are vulnerable to biological invasion; new species can wreak havoc very quickly. The fact that the new techniques allowed the researchers to detect an invader before it dominated the landscape is important to future management strategies. As a result of the findings, the group has expanded to include collaborators from federal, state, and private organizations. Researchers and resource managers from Carnegie, Stanford University, the U.S. National Park Service, NASA, and.........

Posted by: Tyler      Permalink


December 26, 2005, 2:30 PM CT

About Protecting Our Rainforests

The economic benefits of protecting a rainforest reserve outweigh the costs of preserving it, says University of Alberta research-the first of its kind to have conducted a cost-benefit analysis on the conservation of species diversity.

"The traditional moral and aesthetic arguments have been made about why we should conserve the biodiversity in rainforests, but little has been done that looks at whether it makes pure economic sense to do so," said Dr. Robin Naidoo, who did his PhD at the U of A in biological sciences and rural economy. "We provide some good evidence from a strict economic side, that yes, it does".

Naidoo, now with the World Wildlife Fund, and Dr. Wiktor Adamowicz, from the U of A's Department of Rural Economy, examined the costs and benefits of avian biodiversity at the Mabira Forest Reserve in southern Uganda. They wanted to see if it was economically viable to protect this forest in an area where an impoverished community is heavily dependent on the region's resources. Pressure on the forest is intense-harvesting timber, making charcoal, collecting fuel wood and agricultural development compete with rainforest conservation.

An ecotourism centre has been established at the forest since 1996, and a growing number of international tourists continue to visit the reserve. Naidoo and Adamowicz found that the higher the number of bird species that could be seen, the more tourists would be willing to pay. And by increasing entrance fees, the reserve could preserve 90 per cent-or 131 species-of the forest's birds.

"This is one of the few studies where people have put a tangible number on what rainforest biodiversity is worth to them," said Naidoo, adding that the benefits should be distributed to the local people bearing the conservation cost. "And eventhough this is about a Uganda forest, it has international implications".........

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