Odorant shape and vibration likely lead to olfaction satisfaction

ScienceDaily (Sep. 19, 2012) — A new study of the sense of smell lends support to a controversial theory of olfaction: Our noses can distinguish both the shape and the vibrational characteristics of odorant molecules.

The study, in the journal Physical Chemistry Chemical Physics, demonstrates the feasibility of the theory -- first proposed decades ago -- that the vibration of an odorant molecule's chemical bonds -- the wagging, stretching and rocking of the links between atoms -- contributes to our ability to distinguish one smelly thing from another.

"The theory goes that when the right odorant binds to its receptor, the odorant's molecular vibration allows electrons to transfer from one part of the receptor to another," said University of Illinois physics and Beckman Institute professor Klaus Schulten, who conducted the analysis with postdoctoral researcher Ilia Solov'yov and graduate student Po-Yao Chang. "This electron transfer appears to fine-tune the signal the receptor receives."

Many who study olfaction maintain that odorant receptors recognize only an odorant's shape and surface characteristics. They dismiss the idea that molecular vibration has anything to do with it, Schulten said. Likewise, some proponents of the vibrational theory think that molecular vibration only, and not shape, guides the sense of smell. Schulten and his colleagues belong to a "third camp" that sees evidence for both, he said.

The vibrational theory of olfaction is supported by studies showing that insects, humans and other animals can tell the difference between two versions of the same odorant molecule -- a normal one and an identical one with deuterium atoms substituted for each of the hydrogens. The deuterated and normal versions of the odorant have the same shape and surface characteristics, and yet humans and other animals can smell the difference, Schulten said.

"The question then is of course, for scientists, how does this happen?" he said.

To answer this question, Schulten turned to the work of a former colleague at Illinois, Rudolph Marcus, a chemist (now at the California Institute of Technology) who received the Nobel Prize in Chemistry in 1992 for his insights into electron transfer, one of the most basic forms of a chemical reaction.

"Marcus realized that when electrons are being exchanged between molecules the process is coupled to the vibrations of the molecules involved," Schulten said. Marcus focused primarily on the low-frequency "rumblings" that occur as a result of molecular vibration in large molecules, Schulten said.

Odorant molecules are generally quite small, however, with a lot of high-frequency, high-energy vibrations, Schulten said. Some scientists have theorized that these high-frequency vibrations can, when an odorant binds to the right receptor, enhance the likelihood that an electron will transfer from one part of the receptor to another, sending an electrical signal that contributes to the detection of that odor.

Prior to the new study, no one had analyzed the energetics of the system to see if the vibrations of the odorant molecules -- in the context of all the background vibrations that are part of the system -- could actually promote electron transfer within the receptor. Schulten and his colleagues are the first to conduct such an analysis, he said.

"You can actually carry out quantum chemical calculations that determine very precisely the vibration of the molecule as well as the ability to couple it to electron transfer," Schulten said. The calculations indicate that such an interaction is energetically feasible, he said.

Odorant receptors are embedded in membranes and so are more difficult to study than other proteins. But previous research indicates that some receptors are metalloproteins, and "the metals in the proteins are predesigned to transfer electrons," Schulten said. "We also see that there are other amino acid side groups that can accept an electron, so the electron can be transferred through the protein."

Like others before them, Schulten and his colleagues suggest that the odorant receptor contains both an electron donor and an electron acceptor, but that electron transfer occurs only when a specific odorant is bound to the receptor. The new calculations offer the first quantitative evidence that the odorant can in fact promote electron transfer.

Those who suggested that molecular vibration played a role in odorant recognition in previous studies "didn't know about Marcus' theory and they didn't do quantum chemical calculations," Schulten said. "They argued very much on principle (that it was possible). So we are saying now, yes, it is really possible even when you do the most complete and reliable calculations."

Video: http://www.youtube.com/watch?v=Oe5PW2KqImI

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The above story is reprinted from materials provided by University of Illinois at Urbana-Champaign.

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Journal Reference:

1. Ilia A. Solov'yov, Po-Yao Chang, Klaus Schulten. Vibrationally assisted electron transfer mechanism of olfaction: myth or reality? Physical Chemistry Chemical Physics, 2012; DOI: 10.1039/C2CP41436H

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20 Sep, 2012

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Carbon dioxide from water pollution, as well as air pollution, may adversely impact oceans

ScienceDaily (Sep. 19, 2012) — Carbon dioxide (CO₂) released into the oceans as a result of water pollution by nutrients -- a major source of this greenhouse gas that gets little public attention -- is enhancing the unwanted changes in ocean acidity due to atmospheric increases in CO₂. The changes may already be impacting commercial fish and shellfish populations, according to new data and model predictions published September 19 in ACS's journal, Environmental Science & Technology.

William G. Sunda and Wei-Jun Cai point out that atmospheric levels of CO₂, the main greenhouse gas, have increased by about 40 percent since the Industrial Revolution due to the burning of fossil fuels and land-use changes. The oceans absorb about one-third of that CO₂, which results in acidification from the formation of carbonic acid. However, pollution of ocean water with nutrient runoff from fertilizer, human and animal waste, and other sources also is adding CO₂ via the biological breakdown of organic matter formed during algal blooms, which also depletes oxygen from the water.

Sunda and Cai developed a computer model to project the likely consequences of ocean acidification from this process both currently and with future increases in atmospheric CO₂. The model predicted that this process will interact synergistically with the acidification of seawater from rising atmospheric CO₂ in seawater at intermediate to higher temperatures. Together, the two ocean processes are predicted to substantially increase the acidity of ocean waters, enough to potentially impact commercial fisheries in coastal regions receiving nutrient inputs, such as the northern Gulf of Mexico and Baltic Sea. Clams, oysters, scallops and mussels could be the most heavily impacted, the report indicates.

The authors acknowledge funding from the National Science Foundation, the National Aeronautics and Space Administration and the National Oceanic and Atmospheric Administration.

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Journal Reference:

1. William G. Sunda, Wei-Jun Cai. Eutrophication Induced CO2-Acidification of Subsurface Coastal Waters: Interactive Effects of Temperature, Salinity, and AtmosphericPCO2. Environmental Science & Technology, 2012; : 120919060032001 DOI: 10.1021/es300626f

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20 Sep, 2012

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Thermoelectric material is the best at converting heat waste to electricity

ScienceDaily (Sep. 19, 2012) — Northwestern University scientists have developed a thermoelectric material that is the best in the world at converting waste heat to electricity. This is very good news once you realize nearly two-thirds of energy input is lost as waste heat.

The material could signify a paradigm shift. The inefficiency of current thermoelectric materials has limited their commercial use. Now, with a very environmentally stable material that is expected to convert 15 to 20 percent of waste heat to useful electricity, thermoelectrics could see more widespread adoption by industry.

Possible areas of application include the automobile industry (much of gasoline's potential energy goes out a vehicle's tailpipe), heavy manufacturing industries (such as glass and brick making, refineries, coal- and gas-fired power plants) and places were large combustion engines operate continuously (such as in large ships and tankers).

Waste heat temperatures in these areas can range from 400 to 600 degrees Celsius (750 to 1,100 degrees Fahrenheit), the sweet spot for thermoelectrics use.

The new material, based on the common semiconductor lead telluride, is the most efficient thermoelectric material known. It exhibits a thermoelectric figure of merit (so-called "ZT") of 2.2, the highest reported to date. Chemists, physicists, material scientists and mechanical engineers at Northwestern and Michigan State University collaborated to develop the material.

The study will be published Sept. 20 by the journal Nature.

"Our system is the top-performing thermoelectric system at any temperature," said Mercouri G. Kanatzidis, who led the research and is a senior author of the paper. "The material can convert heat to electricity at the highest possible efficiency. At this level, there are realistic prospects for recovering high-temperature waste heat and turning it into useful energy."

Kanatzidis is Charles E. and Emma H. Morrison Professor of Chemistry in Northwestern's Weinberg College of Arts and Sciences. He also holds a joint appointment at Argonne National Laboratory.

"People often ask, what is the energy solution?" said Vinayak P. Dravid, one of Kanatzidis' close collaborators. "But there is no unique solution -- it's going to be a distributed solution. Thermoelectrics is not the answer to all our energy problems, but it is an important part of the equation."

Dravid is the Abraham Harris Professor of Materials Science and Engineering at the McCormick School of Engineering and Applied Science and a senior author of the paper.

Other members of the team and authors of the Nature paper include Kanishka Biswas, a postdoctoral fellow in Kanatzidis' group; Jiaqing He, a postdoctoral member in Dravid's group; David N. Seidman, Walter P. Murphy Professor of Materials Science and Engineering at Northwestern; and Timothy P. Hogan, professor of electrical and computer engineering, at Michigan State University.

Even before the Northwestern record-setting material, thermoelectric materials were starting to get better and being tested in more applications. The Mars rover Curiosity is powered by lead telluride thermoelectrics (although it's system has a ZT of only 1, making it half as efficient as Northwestern's system), and BMW is testing thermoelectrics in its cars by harvesting heat from the exhaust system.

"Now, having a material with a ZT greater than two, we are allowed to really think big, to think outside the box," Dravid said. "This is an intellectual breakthrough."

"Improving the ZT never stops -- the higher the ZT, the better," Kanatzidis said. "We would like to design even better materials and reach 2.5 or 3. We continue to have new ideas and are working to better understand the material we have."

The efficiency of waste heat conversion in thermoelectrics is governed by its figure of merit, or ZT. This number represents a ratio of electrical conductivity and thermoelectric power in the numerator (which need to be high) and thermal conductivity in the denominator (which needs to be low).

"It is hard to increase one without compromising the other," Dravid said. These contradictory requirements stalled the progress towards a higher ZT for many years, where it was stagnant at a nominal value of 1.

Kanatzidis and Dravid have pushed the ZT higher and higher in recent years by introducing nanostructures in bulk thermoelectrics. In January 2011, they published a report in Nature Chemistry of a thermoelectric material with a ZT of 1.7 at 800 degrees Kelvin. This was the first example of using nanostructures (nanocrystals of rock-salt structured strontium telluride) in lead telluride to reduce electron scattering and increase the energy conversion efficiency of the material.

The performance of the new material reported now in Nature is nearly 30 percent more efficient than its predecessor. The researchers achieved this by scattering a wider spectrum of phonons, across all wavelengths, which is important in reducing thermal conductivity.

"Every time a phonon is scattered the thermal conductivity gets lower, which is what we want for increased efficiency," Kanatzidis said.

A phonon is a quantum of vibrational energy, and each has a different wavelength. When heat flows through a material, a spectrum of phonons needs to be scattered at different wavelengths (short, intermediate and long).

In this work, the researchers show that all length scales can be optimized for maximum phonon scattering with minor change in electrical conductivity. "We combined three techniques to scatter short, medium and long wavelengths all together in one material, and they all work simultaneously," Kanatzidis said. "We are the first to scatter all three at once and at the widest spectrum known. We call this a panoscopic approach that goes beyond nanostructuring."

"It's a very elegant design," Dravid said.

In particular, the researchers improved the long-wavelength scattering of phonons by controlling and tailoring the mesoscale architecture of the nanostructured thermoelectric materials. This resulted in the world record of a ZT of 2.2.

The successful approach of integrated all-length-scale scattering of phonons is applicable to all bulk thermoelectric materials, the researchers said.

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Journal Reference:

1. Kanishka Biswas, Jiaqing He, Ivan D. Blum, Chun-I Wu, Timothy P. Hogan, David N. Seidman, Vinayak P. Dravid, Mercouri G. Kanatzidis. High-performance bulk thermoelectrics with all-scale hierarchical architectures. Nature, 2012; 489 (7416): 414 DOI: 10.1038/nature11439

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20 Sep, 2012

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The 'slippery slope to slime': Overgrown algae causing coral reef declines

ScienceDaily (Sep. 19, 2012) — Researchers at Oregon State University for the first time have confirmed some of the mechanisms by which overfishing and nitrate pollution can help destroy coral reefs -- it appears they allow an overgrowth of algae that can bring with it unwanted pathogens, choke off oxygen and disrupt helpful bacteria.

These "macroalgae," or large algal species, are big enough to essentially smother corals. They can get out of control when sewage increases nitrate levels, feeds the algae, and some of the large fish that are most effective at reducing the algal buildup are removed by fishing.

Scientists found that macroalgal competition decreased coral growth rates by about 37 percent and had other detrimental effects. Other research has documented some persistent states of hypoxia.

Researchers call this process "the slippery slope to slime."

Findings on the research were just published in PLoS One, a professional journal.

"There is evidence that coral reefs around the world are becoming more and more dominated by algae," said Rebecca Vega-Thurber, an OSU assistant professor of microbiology. "Some reefs are literally covered up in green slime, and we wanted to determine more precisely how this can affect coral health."

The new study found that higher levels of algae cause both a decrease in coral growth rate and an altered bacterial community. The algae can introduce some detrimental pathogens to the coral and at the same time reduce levels of helpful bacteria. The useful bacteria are needed to feed the corals in a symbiotic relationship, and also produce antibiotics that can help protect the corals from other pathogens.

One algae in particular, Sargassum, was found to vector, or introduce a microbe to corals, a direct mechanism that might allow introduction of foreign pathogens.

There are thousands of species of algae, and coral reefs have evolved with them in a relationship that often benefits the entire tropical marine ecosystem. When in balance, some algae grow on the reefs, providing food to both small and large fish that nibble at the algal growth. But the algal growth is normally limited by the availability of certain nutrients, especially nitrogen and phosphorus, and some large fish such as parrot fish help eat substantial amounts of algae and keep it under control.

All of those processes can be disrupted when algal growth is significantly increased by the nutrients and pollution from coastal waste water, and overfishing reduces algae consumption at the same time.

"This shows that some human actions, such as terrestrial pollution or overfishing, can affect everything in marine ecosystems right down to the microbes found on corals," Vega-Thurber said. "We've suspected before that increased algal growth can bring new diseases to corals, and now for the first time have demonstrated in experiments these shifts in microbial communities."

Some mitigation of the problem is already being done on high-value coral reefs by mechanically removing algae, Vega-Thurber said, but the best long-term solution is to reduce pollution and overfishing so that a natural balance can restore itself.

Corals are one of Earth's oldest animal life forms, evolving around 500 million years ago. They host thousands of species of fish and other animals, are a major component of marine biodiversity in the tropics, and are now in decline around the world. Reefs in the Caribbean Sea have declined more than 80 percent in recent decades.

The work was supported by the National Science Foundation.

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Journal Reference:

1. Rebecca Vega Thurber, Deron E. Burkepile, Adrienne M. S. Correa, Andrew R. Thurber, Andrew A. Shantz, Rory Welsh, Catharine Pritchard, Stephanie Rosales. Macroalgae Decrease Growth and Alter Microbial Community Structure of the Reef-Building Coral, Porites astreoides. PLoS ONE, 2012; 7 (9): e44246 DOI: 10.1371/journal.pone.0044246

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20 Sep, 2012

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How organisms evolve new functions: Evolution is as complicated as 1-2-3

ScienceDaily (Sep. 19, 2012) — A team of researchers at Michigan State University has documented the step-by-step process in which organisms evolve new functions.

The results, published in the current issue of Nature, are revealed through an in-depth, genomics-based analysis that decodes how E. coli bacteria figured out how to supplement a traditional diet of glucose with an extra course of citrate.

"It's pretty nifty to see a new biological function evolve," said Zachary Blount, postdoctoral researcher in MSU's BEACON Center for the Study of Evolution in Action. "The first citrate-eaters were just barely able to grow on the citrate, but they got much better over time. We wanted to understand the changes that allowed the bacteria to evolve this new ability. We were lucky to have a system that allowed us to do so."

Normal E. coli can't digest citrate when oxygen is present. In fact, it's a distinct hallmark of E. coli. They can't eat citrate because E. coli don't express the right protein to absorb citrate molecules.

To decipher the responsible mutations, Blount worked with Richard Lenski, MSU Hannah Distinguished Professor of Microbiology and Molecular Genetics. Lenski's long-term experiment, cultivating cultures of fast-growing E. coli, was launched in 1988 and has allowed him and his teammates to study more than more than 56,000 generations of bacterial evolution.

The experiment demonstrates natural selection at work. And because samples are frozen and available for later study, when something new emerges scientists can go back to earlier generations to look for the steps that happened along the way.

"We first saw the citrate-using bacteria around 33,000 generations," Lenski explained. "But Zack was able to show that some of the important mutations had already occurred before then by replaying evolution from different intermediate stages. He showed you could re-evolve the citrate-eaters, but only after some of the other pieces of the puzzle were in place."

In the Nature paper, Blount and his teammates analyzed 29 genomes from different generations to find the mutational pieces of the puzzle. They uncovered a three-step process in which the bacteria developed this new ability.

The first stage was potentiation, when the E. coli accumulated at least two mutations that set the stage for later events. The second step, actualization, is when the bacteria first began eating citrate, but only just barely nibbling at it. The final stage, refinement, involved mutations that greatly improved the initially weak function. This allowed the citrate eaters to wolf down their new food source and to become dominant in the population.

"We were particularly excited about the actualization stage," Blount said. "The actual mutation involved is quite complex. It re-arranged part of the bacteria's DNA, making a new regulatory module that had not existed before. This new module causes the production of a protein that allows the bacteria to bring citrate into the cell when oxygen is present. That is a new trick for E. coli."

The change was far from normal, Lenski said.

"It wasn't a typical mutation at all, where just one base-pair, one letter, in the genome is changed," he said. "Instead, part of the genome was copied so that two chunks of DNA were stitched together in a new way. One chunk encoded a protein to get citrate into the cell, and the other chunk caused that protein to be expressed."

Additional co-authors include Jeff Barrick, University of Texas, and Carla Davidson, University of Calgary.

The research was funded in part by the National Science Foundation.

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Journal Reference:

1. Zachary D. Blount, Jeffrey E. Barrick, Carla J. Davidson, Richard E. Lenski. Genomic analysis of a key innovation in an experimental Escherichia coli population. Nature, 2012; DOI: 10.1038/nature11514

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20 Sep, 2012

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CT scan and 3-D print help scientists reconstruct an ancient mollusk

ScienceDaily (Sep. 19, 2012) — Using a combination of traditional and innovative model-building techniques, scientists in the U.S. and a specialist in Denmark have created a lifelike reconstruction of an ancient mollusk, offering a vivid portrait of a creature that lived about 390 million years ago, and answering questions about its place in the tree of life, as described in the Sept. 18 edition of the journal Palaeontology.

The model of the oval-shaped sea creature, called a multiplacophoran, which was covered with stiff plates and a ring of spines, resulted from a collaboration between Jakob Vinther, a postdoctoral researcher at The University of Texas at Austin's Jackson School of Geosciences, and Esben Horn, owner of the model making company 10 Tons in Copenhagen (http://www.10tons.dk), with animation help from Ryan Carney, a doctoral student at Brown University.

Working with a delicate specimen of a multiplacophoran partially covered by rock, Vinther used a micro CT scan -- a noninvasive technology similar to medical CAT scanning -- to create a three-dimensional view of the fossil. With Carney's help, the CT scan yielded an animated view of the original placement of the creature's dense spines and shells, which had splayed out and decayed prior to fossilization.

The CT scan also produced a three-dimensional cast of the specimen in its reconstructed shape. Working with the cast, the animation and information on living relatives of the multiplacophorans, Horn was able to create a multicolored, textured model in clay, resin and silicone showing how the creature looked millions of years ago, when it crawled on a single, suction-like foot over shells and rocky surfaces in ancient oceans.

The model helps address a debate about how multiplacophorans (which were only discovered in the past decade) relate to chitons, another more widely known plated mollusk that lives on seashores and is commonly eaten in the Caribbean. By dating the origin of modern chitons, Vinther could demonstrate that multiplacophorans are stem group chitons.

"We can now demonstrate that multiplacophorans are distant relatives of the modern chitons, which did not evolve until later in Earth history," said Vinther. "We can also show that they evolved a number of characteristics seen in some modern chitons convergently."

The CT scan was integral to the project, allowing the scientists to see below the surface of the fossil.

"CT scanning is an extremely powerful technique for paleontologists," said Vinther, "since we can look inside fossils without destroying them."

The original fossil was discovered 10 years ago in Ohio by private collector and co-author George Kampouris, who donated it to the Cincinnati Museum of Natural History.

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Journal Reference:

1. Jakob Vinther, Peter Jell, George Kampouris, Ryan Carney, Rachel A. Racicot, Derek E. G. Briggs. The origin of multiplacophorans - convergent evolution in Aculiferan molluscs. Palaeontology, 2012; 55 (5): 1007 DOI: 10.1111/j.1475-4983.2012.01180.x

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20 Sep, 2012

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Self-forming biological scaffolding

ScienceDaily (Sep. 19, 2012) — A new model system of the cellular skeletons of living cells is akin to a mini-laboratory designed to explore how the cells' functional structures assemble. A paper about to be published in EPJ E by physicist Volker Schaller and his colleagues from the Technical University Munich, Germany, presents one hypothesis concerning self-organisation. It hinges on the findings that a homogeneous protein network, once subjected to stresses generated by molecular motors, compacts into highly condensed fibres.

The contractile machinery inside cells is arguably the most prominent example of cells' ability to self-organise cellular proteins into highly ordered functional structures involved in cell division or cell migration, for example.

The authors attempt to elucidate how such highly self-organised structures emerge from a less ordered and homogeneous collection of constituent proteins. Namely, such proteins are actin filaments -- one of the main scaffold proteins in cells made of biopolymers -- and associated molecular motors. The latter exerts forces by pressing along the filament, an energy consuming process.

Schaller and colleagues reconstituted a minimal model system of the cellular skeleton consisting of actin filaments held together by cross-linking proteins and molecular motors. They found that this minimal system is sufficient to reproduce similar self-organisation processes observed in nature.

In particular, they showed that a homogeneous network of actin filaments held together by the cross-linking protein α-actinin can rapidly be reorganised by molecular motor proteins. It contracts to form a highly heterogeneous set of compact fibres consisting of millions of individual filaments, resembling scaffold structures inside the cellular skeleton.

The authors also realised that the efficiency of this reorganisation process, and therefore the length scale of the fibres created, directly depend on motor activity. Thus, the fibres can range between 5μm and up to 100μm in length for low and high motor activity, respectively.

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Journal Reference:

1. V. Schaller, B. Hammerich, A. R. Bausch. Active compaction of crosslinked driven filament networks. The European Physical Journal E, 2012; 35 (8) DOI: 10.1140/epje/i2012-12081-2

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19 Sep, 2012

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Major changes needed to protect Australia's species and ecosystems

ScienceDaily (Sep. 18, 2012) — A landmark study has found that climate change is likely to have a major impact on Australia's plants, animals and ecosystems that will present significant challenges to the conservation of Australia's biodiversity.

The comprehensive study by CSIRO highlights the sensitivity of Australia's species and ecosystems to climate change, and the need for new ways of thinking about biodiversity conservation.

"Climate change is likely to start to transform some of Australia's natural landscapes by 2030," lead researcher, CSIRO's Dr Michael Dunlop said.

"By 2070, the ecological impacts are likely to be very significant and widespread. Many of the environments our plants and animals currently exist in will disappear from the continent. Our grandchildren are likely to experience landscapes that are very different to the ones we have known."

Dr Dunlop said climate change will magnify existing threats to biodiversity, such as habitat clearing, water extraction and invasive species. Future climate-driven changes in other sectors, such as agriculture, water supply and electricity supply, could add yet more pressure on species and ecosystems.

"These other threats have reduced the ability of native species and ecosystems to cope with the impacts of climate change," Dr Dunlop said.

One of the challenges for policy and management will be accommodating changing ecosystems and shifting species.

The study suggests the Australian community and scientists need to start a rethink of what it means to conserve biodiversity, as managing threatened species and stopping ecological change becomes increasingly difficult.

"We need to give biodiversity the greatest opportunity to adapt naturally in a changing and variable environment rather than trying to prevent ecological change," Dr Dunlop said.

The study highlights the need to start focusing more on maintaining the health of ecosystems as they change in response to climate change, from one type of ecosystem to another.

'This could need new expectations from the community, possibly new directions in conservation policy, and new science to guide management," Dr Dunlop said.

"To be effective we also need flexible strategies that can be implemented well ahead of the large-scale ecological change. It will probably be too late to respond once the ecological change is clearly apparent and widespread."

The study found the National Reserve System will continue to be an effective conservation tool under climate change, but conserving habitat on private land will be increasingly important to help species and ecosystems adapt.

The team of researchers from CSIRO carried out modelling across the whole of Australia, as well as detailed ecological analysis of four priority biomes, together covering around 80 per cent of Australia.

The study was funded by the Australian Government Department of Sustainability, Environment, Water, Population and Communities, the Department of Climate Change and Energy Efficiency and the CSIRO Climate Adaptation Flagship.

Further information: http://www.csiro.au/Organisation-Structure/Flagships/Climate-Adaptation-Flagship/adapt-national-reserve-system.aspx

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19 Sep, 2012

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Did a 'forgotten' meteor have a deadly, icy double-punch?

ScienceDaily (Sep. 19, 2012) — When a huge meteor collided with Earth about 2.5 million years ago and fell into the southern Pacific Ocean it not only could have generated a massive tsunami but also may have plunged the world into the Ice Ages, a new study suggests.

A team of Australian researchers says that because the Eltanin meteor -- which was up to two kilometres across -- crashed into deep water, most scientists have not adequately considered either its potential for immediate catastrophic impacts on coastlines around the Pacific rim or its capacity to destabilise the entire planet's climate system.

"This is the only known deep-ocean impact event on the planet and it's largely been forgotten because there's no obvious giant crater to investigate, as there would have been if it had hit a landmass," says Professor James Goff, lead author of a forthcoming paper in the Journal of Quaternary Science. Goff is co-director of UNSW's Australia-Pacific Tsunami Research Centre and Natural Hazards Research Laboratory.

"But consider that we're talking about something the size of a small mountain crashing at very high speed into very deep ocean, between Chile and Antarctica. Unlike a land impact, where the energy of the collision is largely absorbed locally, this would have generated an incredible splash with waves literally hundreds of metres high near the impact site.

"Some modelling suggests that the ensuing mega-tsunami could have been unimaginably large -- sweeping across vast areas of the Pacific and engulfing coastlines far inland. But it also would have ejected massive amounts of water vapour, sulphur and dust up into the stratosphere.

"The tsunami alone would have been devastating enough in the short term, but all that material shot so high into the atmosphere could have been enough to dim the sun and dramatically reduce surface temperatures. Earth was already in a gradual cooling phase, so this might have been enough to rapidly accelerate and accentuate the process and kick start the Ice Ages."

In the paper, Goff and colleagues from UNSW and the Australian Nuclear Science and Technology Organisation, note that geologists and climatologists have interpreted geological deposits in Chile, Antarctica, Australia, and elsewhere as evidence of climatic change, marking the start of the Quaternary period. An alternative interpretation is that some or all of these deposits may be the result of mega-tsunami inundation, the study suggests.

"There's no doubt the world was already cooling through the mid and late Pliocene," says co-author Professor Mike Archer. "What we're suggesting is that the Eltanin impact may have rammed this slow-moving change forward in an instant -- hurtling the world into the cycle of glaciations that characterized the next 2.5 million years and triggered our own evolution as a species.

"As a 'cene' changer -- that is, from the Pliocene to Pleistocene -- Eltanin may have been overall as significant as the meteor that took out the non-flying dinosaurs 65 million years ago. We're urging our colleagues to carefully reconsider conventional interpretations of the sediments we're flagging and consider whether these could be instead the result of a mega-tsunami triggered by a meteor."

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Story Source:

The above story is reprinted from materials provided by University of New South Wales. The original article was written by Bob Beale.

Note: Materials may be edited for content and length. For further information, please contact the source cited above.

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Journal Reference:

1. James Goff, Catherine Chagué-Goff, Michael Archer, Dale Dominey-Howes, Chris Turney. The Eltanin asteroid impact: possible South Pacific palaeomegatsunami footprint and potential implications for the Pliocene-Pleistocene transition. Journal of Quaternary Science, 2012; DOI: 10.1002/jqs.2571

Note: If no author is given, the source is cited instead.

Disclaimer: Views expressed in this article do not necessarily reflect those of ScienceDaily or its staff.

19 Sep, 2012

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Source: http://feeds.sciencedaily.com/~r/sciencedaily/top_news/top_environment/~3/W-AEZjbS5oc/120919103612.htm
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Modern DNA techniques applied to nineteenth-century potatoes

ScienceDaily (Sep. 19, 2012) — Researchers led by Professor Bruce Fitt, now at the University of Hertfordshire, have used modern DNA techniques on late nineteenth-century potatoes to show how the potato blight may have survived between cropping seasons after the Irish potato famine of the 1840s.

Late blight of potato is caused by the microorganism, Phytophthora infestans, which rapidly destroys the leaves of potato crops and was responsible for the infamous Irish potato famine of the 1840s that left over one million people dead and another one million Irish emigrating. With growing concerns over food shortages and climate change, late blight remains a serious disease problem in current potato production and has also emerged as a significant disease threat to the organic tomato industry.

In the research paper published in Plant Pathology, DNA was extracted from the Rothamsted potato samples that had been dried, ground and stored in glass bottles in the nineteenth century. The DNA was then analysed for the presence of the potato blight pathogen.

Bruce Fitt, Professor of Plant Pathology at the University of Hertfordshire and formerly at Rothamsted Research, said: "It was the foresight of two nineteenth-century plant scientists to archive potato samples from their experiment that has enabled us to apply modern DNA techniques to better understand late potato blight and the implications for today's food security. The analysis of these late nineteenth-century potato samples is the earliest proof of how this disease survived between seasons in England."

The findings of this research has proved that the DNA technique applied to the potato samples is a very useful tool in plant disease diagnosis to test seed potatoes or tomato transplants for the presence of the late blight pathogen. This technique can be further developed for testing for other diseases found in different plants which affect food production.

Bruce continued: "Using modern DNA techniques to detect and quantify the pathogen in potatoes enables us to better understand the spread of potato late blight. This disease is still a serious threat to worldwide potato production."

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Story Source:

The above story is reprinted from materials provided by University of Hertfordshire, via AlphaGalileo.

Note: Materials may be edited for content and length. For further information, please contact the source cited above.

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Journal Reference:

1. J. B. Ristaino, C. H. Hu, B. D. L. Fitt. Evidence for presence of the founder Ia mtDNA haplotype of Phytophthora infestans in 19th century potato tubers from the Rothamsted archives. Plant Pathology, 2012; DOI: 10.1111/j.1365-3059.2012.02680.x

Note: If no author is given, the source is cited instead.

Disclaimer: Views expressed in this article do not necessarily reflect those of ScienceDaily or its staff.

19 Sep, 2012

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Source: http://feeds.sciencedaily.com/~r/sciencedaily/top_news/top_environment/~3/voQn23516Vs/120919083403.htm
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