January 18, 2006, 7:40 PM CT

Sequencing Three Fungus Genomes

From garden compost to forest greenery, the mold Aspergillus fumigatus lurks across much of the world. And so does its impact. The most common mold causing infection, A. fumigatus triggers allergic reactions, asthma attacks--and even deadly infections among people with weakened immune systems.

Now, in the December 22 issue of the journal Nature, scientists at The Institute for Genomic Research (TIGR) and their collaborators report the mold's sequenced genome. The genome could lead researchers to A. fumigatus genes with the potential to generate better diagnostics and treatment for fungal infection. "This genome sequence is going to be central for developing tools for effectively managing A. fumigatus infections as they become more prevalent in the aging population," predicts first author William Nierman, a microbiologist at TIGR.

Nierman co-authored two additional Aspergillus genome papers in the same issue of Nature. One describes a genome project on Aspergillus oryzae, a nonpathogenic food industry workhorse that has produced sake (rice wine), miso (soybean paste), and shoyu (soy sauce) for 2,000 years. The third paper reports the genome sequence of model organism Aspergillus nidulans and compares the organism to A. oryzae and A. fumigatus. The work was carried out collaboratively at several institutions in the U.S., U.K., Spain, Japan, France, Brazil, Austria, Switzerland, and Germany. David Denning of the University of Manchester coordinated the projects.........

Posted by: Ashley      Permalink


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 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


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, 10:23 PM CT

How Growth Hormones Work In Plants

Both plant and animal growth is controlled by steroid hormones-signaling molecules that tell specific genes in cells to begin the physiological process of increasing cell size. Although these molecular managers operate similarly in plants and animals, the chain of events in regulating cellular functions appears to be very different in the two kingdoms. In animals, hormone reception begins in the nucleus of the cell. In plants, a steroid hormone family called brassinosteroids (BRs) start to work on the surface of the cell. A bucket-brigade of activity then wins its way into the cell's nucleus to activate specific genes that tell the cell to grow. "We found a key component in this complex chain reaction in the cell nucleus that promotes cell growth," stated co-author Zhi-Yong Wang, of Carnegie's Department of Plant Biology in Stanford, CA. The research has important implications for the possibility of understanding how to manipulate the signaling machinery to increase plant growth and yield. The paper is published in the January 27, 2005, Science Express.

As Wang explained: "We've known for some time what happens at the cell's surface, so understanding what is happening in the nucleus is very important for unraveling this mystery of plant growth. We found that in the model plant Arabidopsis, a protein in the cell nucleus called BZR1, which is activated when the BR hormone is present, has a previously unknown segment where molecular binding occurs. Instead of stimulating an activity, the protein binds to a DNA sequence (named brassinosteriod-response element or BRRE), which stops the process of transcription--the transfer of genetic information from the DNA template molecule to messenger RNA--for a gene named CPD. Because the CPD gene orders the production of an enzyme needed for BR synthesis, this suppression stops the production of BR conferring a feedback regulation of BR production. When the BR steroid level is high, BZR1 is activated and BR synthesis is reduced. When the level is low, the synthesis is high. This feedback regulation is critical for maintaining an optimal steroid level for plant growth.........

Posted by: Jessica      Permalink


December 26, 2005, 5:31 PM CT

Increasing Carbon Retention In Soil

Scientists from the U.S. Department of Energy's Argonne National Laboratory - with collaborators from Oak Ridge National Laboratory, Kansas State University and Texas AandM University- have shown that soils in temperate ecosystems might play a larger role in helping to offset rising atmospheric carbon dioxide (CO2 ) concentrations than earlier studies had suggested. Results of the new study are published in the current issue of Global Change Biology.

Higher CO2 concentrations often stimulate plant growth. A subsequent increase in the amount of decaying plant material might then lead to an accumulation of carbon in soil. Yet nearly all field experiments to date have failed to demonstrate changes in soil carbon against the large and variable background of existing soil organic matter.

In this new study, funded by DOE's Office of Science, researchers overcame that issue using a statistical technique called meta-analysis. This analysis of earlier published experiments showed that elevated CO2 concentrations - ranging from double pre-industrial levels to double current levels - increased carbon in soil surface layers by an average of 5.6 percent across diverse temperate ecosystems. If a response of this magnitude occurred globally for all temperate systems in a CO2 -enriched world, the authors calculated that increased soil carbon storage might remove 8 to 13 billion metric tons of carbon from the atmosphere over a period of about 10 years.........

Posted by: Jessica      Permalink


December 26, 2005, 2:06 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".........

Posted by: Jaison      Permalink