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noreply@blogger.com (Surendran) — Fri, 15 May 2009 17:14:00 +0000

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Theory Of Sun's Role In Formation Of Solar System Questioned

noreply@blogger.com (Surendran) — Sun, 07 Sep 2008 03:37:00 +0000

Theory Of Sun's Role In Formation Of Solar System Questioned

A strange mix of oxygen found in a stony meteorite that exploded over Pueblito de Allende, Mexico nearly 40 years ago has puzzled scientists ever since.

Small flecks of minerals lodged in the stone and thought to date from the beginning of the solar system have a pattern of oxygen types, or isotopes, that differs from those found in all known planetary rocks, including those from Earth, its Moon and meteorites from Mars.

Now scientists from UC San Diego and Lawrence Berkeley National Laboratory have eliminated one model proposed to explain the anomaly: the idea that light from the early Sun could have shifted the balance of oxygen isotopes in molecules that formed after it turned on. When they beamed light through carbon monoxide gas to form carbon dioxide, the balance of oxygen isotopes in the new molecules failed to shift in ways predicted by the model they report in the September 5 issue of Science.

"It's solar system forensics. We're understanding a little about how it got made," said Mark Thiemens, Dean of the Division of Physical Sciences and a professor of chemistry and biochemistry at UC San Diego, who directed the project. The results pare down the potential explanations for how gas and dust coalesced to form the planets and will help this team and others interpret samples of the solar wind returned by NASA's Genesis spacecraft.

Atomic Shield

Scientists think the early Sun emitted intense far-ultraviolet light. Light energy at these very short wavelengths will dislodge oxygen atoms from molecules, freeing them to hook up with others in new combinations. In the process, the oxygen atoms absorb some of the energy.

This is how gases became dust and then larger minerals that collided and continued to build to form the planets. Oxygen, the most abundant element in the solar system, is a player in almost all of these reactions.

Each oxygen isotope responds to a unique set of light wavelengths. An abundance of a particular oxygen isotope within in a cloud of gas molecules will quench the light at its preferred wavelengths, shielding gas molecules farther along the light's path. Other wavelengths, including those that dislodge different oxygen isotopes, will continue unimpeded, favoring the inclusion of these rarer isotopes in new molecules.

The balance of oxygen isotopes found in the Allende meteorite is tipped toward the most abundant one, 16O. Planetary rocks have relatively more rarer heavier oxygen isotopes, as though rare isotopes were preferred as the planets formed.

Photo Effect

"We decided to directly test this idea that photoshielding could change the isotope ratios," said Subrata Chakraborty, a postdoctoral fellow at UC San Diego and first author of the paper.

The team focused an intense beam of far-ultraviolet light generated by the Lawrence Berkeley National Laboratory's Advanced Light Source into a tube filled with carbon monoxide gas. The light knocked some of the oxygen atoms free, allowing them to recombine with other carbon monoxide molecules to form carbon dioxide. Chakraborty then collected and analyzed the carbon dioxide to determine the balance of oxygen isotopes in the new molecules.

By precisely controlling the wavelength of the light, the scientists were able to set up conditions that should have resulted in oxygen isotope mixes that matched either those found on Earth or in the Allende meteorite.

Wavelengths known to be absorbed by 16O should result in carbon dioxide molecules enriched with the heavier forms of oxygen. They tested two of these wavelengths: one enriched the mix; the other did not.

Wavelengths not absorbed by 16O should result in a mix that matched that found in the Allende meteorite. Again, of the two the team tested, one did and one did not. "Some process is altering the mix, but it can't be photoshielding," Chakraborty said.

Original Mix

Samples returned by the GENESIS spacecraft will have to be interpreted in light of these results, Thiemens said. By analyzing samples of the Sun's outer atmosphere captured from the solar wind, the mission aims to determine the original composition of the solar nebula, the swirl of dust and gas that formed the solar system. Measurements by Thiemen's research group and others will help to resolve the chemical mismatch between the meteorite inclusions and planetary rocks.

Several other models have been proposed to explain the anomaly--including the idea that an exploding star could have blasted in an extra dose of 16O--only to have been discarded when experimental evidence showed them to be unlikely.

The only one left standing, according to Thiemens, is an idea called molecular symmetry that says an atom flanked by two oxygen isotopes is more likely to become a stable molecule if the two isotopes are mismatched. This quieter process would also favor the formation of molecules that included rarer oxygen isotopes.

"There's no violence," Thiemens said. "It doesn't require a star blowing up or turning on to cast a nebula-wide shadow. It's symmetry."

Musahid Ahmed of Lawrence Berkeley National Laboratory and Teresa Jackson of UC San Diego are co-authors of the paper. NASA and the Department of Energy funded the project.

Forensic Scientists Improve DNA Analysis With Mummy-inspired Bone-baking

noreply@blogger.com (Surendran) — Wed, 03 Sep 2008 17:34:00 +0000

Baking Out DNA

Forensic Scientists Improve DNA Analysis With Mummy-inspired Bone-baking

Forensic scientists analyzing bones found in the Gobi desert discovered that the DNA within them could be surprisingly easily extracted. In an experiment designed to mimic the conditions that affected those bones, baking a particularly difficult sample made the DNA much more easily extracted, probably because it makes it easier to break open more cells and expose more of the DNA molecules.

Mummies have always held secrets, but now one of them has led to a new DNA technique.

Our fascination with mummies has sold millions at the box office. Now these preserved people -- mummies more than 800 years old -- are helping scientists reveal the mysteries of the past.

University of New Haven forensic scientist Dr. Heather Coyle is experimenting with a new technique by going back in time.

These are skeletal remains recently gathered from a Gobi desert cave. Surprisingly, Dr. Coyle was able to extract DNA from these mummies, but when she tried the same method on a body found in the USA, she was not as successful. "We realized that the bone we were trying to process was not yielding DNA from the case we were working on," Dr. Coyle said.

Standard DNA procedure for bones is to freeze them. When Coyle and her team re-examined the mummy remains they realized the Gobi desert created a natural bone baking process.

"It makes the bone more brittle so it makes it easier to grind and break open more cells, so we think we are accessing more DNA to begin with," Dr. Coyle said. Dr. Coyle decided to mimic nature by baking the cold case bones for 72 hours. Liquid nitrogen was then poured into a pulverizer. The bone was placed inside, ready to be crushed. After a short cycle the bone was turned to powder and ready for DNA extraction.

Coyle hopes her new technique will someday help close the book on several cold case files.

What is DNA? DNA is the blueprint that encodes all the data for building a human body, along with instructions on how it should operate. Every cell in a person's body contains a copy of this DNA.

DNA typing is based on an unusual feature found in the human genome. There are multiple copies of certain short sequences, 3 to 30 base pairs long, that are repeated one after another as many as 100 times. These groups of repeat sequences are widely scattered through the genome. Everyone has these repeat units, but the number varies from person to person.

Only identical twins will have the same numbers and patterns of these sequences. These genetic data aren't instructions to make anything; scientists think they might exist to get mixed up in the regular genes and provide some variety for evolution.

Person's Geographic Origins Located From DNA

noreply@blogger.com (Surendran) — Wed, 03 Sep 2008 17:32:00 +0000

Person's Geographic Origins Located From DNA

One day soon, you may be able to pinpoint the geographic origins of your ancestors based on analysis of your DNA.

A study published online this week in Nature by an international team that included Cornell University researchers describes the use of DNA to predict the geographic origins of individuals from a sample of Europeans, often within a few hundred kilometers of where they were born.

"What we found is that within Europe, individuals with all four grandparents from a given region are slightly more similar genetically to one another, on average, than to individuals from more distant regions," said Carlos Bustamante, associate professor of biological statistics and computational biology at Cornell and the paper's senior author. John Novembre, an assistant professor in the University of California-Los Angeles' Department of Ecology and Evolution, was lead author of the study that also included researchers from GlaxoSmithKline, the University of Chicago and the University of Lausanne (Switzerland).

"When these minute differences are compounded across the whole of their genome, we have surprisingly high power to predict where in Europe they came from," Bustamante added.

This is one of the first studies to examine genome-wide patterns of genetic variation across a large sample of Europeans, and to use these data to predict ancestry. The methodology has wide-ranging implications for using DNA samples from unrelated individuals to identify genes underlying complex diseases, as well as forensics, personalized genomics and the study of recent human history.

Using data from a sample of almost 3,200 Europeans supplied by GlaxoSmithKline, the team analyzed more than 500,000 genetic points known as single nucleotide polymorphisms (SNPs), or minute sequence variations in DNA. The researchers focused its analysis on individuals for whom all the grandparents were believed to come from the same country. The team simplified and plotted the data, revealing that individuals with similar genetic structures clustered together on the plot in such a way that the major geographic features of Europe became distinguishable.

"What is really surprising is that when we summarize the data from 500,000 SNPs in just two dimensions, we see this striking map of Europe," said Novembre. "We can recognize the Iberian peninsula, the Italian peninsula, southeastern Europe, Turkey and Cyprus."

The resolution of the genetic map was so precise that the investigators were able to find genetic differences among the French, German and Italian-speaking Swiss individuals; with French speakers being more similar to the French, German speakers to Germans and Italian speakers to Italians.

Based on these observations, Novembre and colleagues from the University of Chicago developed a novel algorithm for classifying individuals geographically based on their patterns of DNA variation.

For well-sampled countries, this approach placed 50 percent of individuals within 310 kilometers (km) of their reported origin, and 90 percent within 700 km of their origin. Across all populations, 50 percent of individuals were placed within 540 km of their reported origin and 90 percent of individuals within 840 km. The findings excluded individuals with grandparents from different countries, since these were assigned locations between their grandparents' origins. Some next steps will be to infer origins for people with recent ancestry from multiple locations and to perform similar analyses for populations on other continents.

The study was funded by the Giorgi-Cavaglieri Foundation, the Swiss National Science Foundation, the National Science Foundation and the National Institutes of Health in the U.S., and GlaxoSmithKline.

Scent Lures Mosquitoes

noreply@blogger.com (Surendran) — Mon, 01 Sep 2008 18:06:00 +0000

No More Big Stink: Scent Lures Mosquitoes, But Humans Can't Smell It

Mosquito traps that reek like latrines may be no more. A University of California, Davis research team led by chemical ecologist Walter Leal has discovered a low-cost, easy-to-prepare attractant that lures blood-fed mosquitoes without making humans hold their noses.

The synthetic mixture, containing compounds trimethylamine and nonanal in low doses, is just as enticing to Culex mosquitoes as the current attractants, Leal said, but this one is odorless to humans.

The research, published in the current edition of the Public Library of Science Journal or PLoS One, could play a key role in surveillance and control programs for Culex species, which transmit such diseases as West Nile virus, encephalitis and lymphatic filariasis.

Oviposition or gravid female traps draw blood-fed mosquitoes ready to lay their eggs, but the chemical- and water-infused traps just plain stink, Leal said. The smell is highly offensive to those monitoring the traps and to people living near them.

That prompted the UC Davis researchers to launch a multidisciplinary approach to find more user-friendly, chemically based lures for gravid Culex mosquitoes.

Their extensive field research in Recife, Brazil, a region known for its high populations of Culex quiquefasciatus, showed that a combination of trimethylamine and nonanal “is equivalent to the currently used infusion-based lure,” Leal said, “and superior in that the offensive smell of infusions was eliminated.”

The Leal lab searches for attractants in two ways. The first is the conventional chemical ecology approach or finding smells that attract mosquitoes. The second, or what Leal has coined “reverse chemical ecology,” involves studying olfaction after identifying attractants.

Mosquito populations are typically monitored with two traps: the conventional carbon dioxide traps and the gravid female trap. Mosquitoes captured in the carbon dioxide traps are less likely to be infected than those in the gravid traps.

“The gravid traps are more important for surveillance,” Leal said, “as they capture mosquitoes that have had a blood meal and thus, more opportunity to become infected.”

By monitoring gravid traps containing West Nile virus-infected mosquitoes, mosquito and vector control districts and health officials can determine when it is time to spray.

Leal said that another advantage of the gravid traps is that with the capture of one female mosquito, that eliminates not only her, but hundreds of her would-be offspring. “Each female mosquito has the potential to produce about 200 eggs, and she can have as many as five cycles. So when we capture a gravid mosquito, that can remove as many as 500 females.”

UC Davis research entomologist William Reisen said sampling Culex species in urban environments can be challenging, but the gravid trap work is crucial.

Because the Southern house mosquito, Culex quinquefasciatus, feeds on the blood of a wide variety of hosts, the West Nile virus can move rapidly through bird and human populations, according to Reisen.

“Sampling the species in urban environments has been a challenge until studies on its oviposition cues allowed the development of gravid female traps that collect mostly females that previously have blood-fed and, therefore, had a chance to become infected,” Reisen.

Leal said the compounds used in the research are “simple and inexpensive” and would be of great benefit “to not only us, but third-world countries where Culex quinquefasciatus is a problem.”

The researchers began preliminary field tests in Davis and Sacramento but when aerial sprays mitigated the levels of West Nile virus-infested mosquitoes, they set up traps in Recife, Brazil, a city endemic for lymphatic filariasis.

Scientists involved in the study with Leal were UC Davis researchers Wei Xi, Yuko Ishida, Zain Syed, Nicolas Latte, Angela Chen and Tania Morgan; Anthony Cornel, associate professor of entomology at UC Davis and director of the Mosquito Control Research Laboratory, based at the Kearney Agricultural Center, Parlier; and Rosângela M. R. Barbosa and André Furtado of the Department of Entomology, Centro de Pesquisas Ageu Magalhaes-Fiocruz, Recife, Brazil.

Monkey Population - Cambodia

noreply@blogger.com (Surendran) — Sun, 31 Aug 2008 17:24:00 +0000

Unexpected Large Monkey Population Discovered In Cambodia: Tens Of Thousands Of Threatened Primate

A Wildlife Conservation Society report reveals surprisingly large populations of two globally threatened primates in a protected area in Cambodia.

The report counted 42,000 black-shanked douc langurs along with 2,500 yellow-cheeked crested gibbons in Cambodia's Seima Biodiversity Conservation Area, an estimate that represents the largest known populations for both species in the world.

WCS scientists conducted the surveys with the Royal Government of Cambodia's Ministry of Agriculture, Forestry and Fisheries across an area of 300 square miles (789 square kilometers) within a wider landscape of 1,150 square miles (3,000 square kilometers), which is about the size of Yosemite National Park. The scientists believe total populations within the wider landscape may be considerably greater.

The WCS scientists who worked on the census include Tom Clements, Nut Meng Hor, Men Soriyun, Edward Pollard, Hannah O'Kelly, and Samantha Strindberg.

The data were first presented at the International Primatological Society Congress held recently in Edinburgh, Scotland. WCS also announced at the IPS Congress the discovery of 125,000 western lowland gorillas in northern Republic of Congo, where conservation work has been ongoing since the early 1990s.

"Whether it's protecting gorillas in the Republic of Congo or monkeys and gibbons in Cambodia, conservation can and does work when you have government commitment and scientific knowledge on the ground ," said Dr. John G. Robinson, Executive Vice President for Conservation and Science for the Wildlife Conservation Society. "Now we must put into place the management to truly protect these populations and apply the approach to other regions where primates are in trouble."

The two primate species are found in much lower numbers at other sites in Cambodia and in Vietnam. Prior to the recent discovery in the Seima Biodiversity Conservation Area, the largest known populations were believed to be in adjacent Vietnam, where black-shanked douc langurs and yellow-cheeked crested gibbons hover at 600 and 200 respectively. The total population of the two species remains unknown.

The recent census in Cambodia took place in a former logging area where the two monkeys were once extensively hunted. Then in 2002, the Minister of Agriculture, Forestry and Fisheries declared the region a conservation area and began working with WCS on site management and landscape-level planning for conservation and local development.

According to WCS, a combination of factors account for such high numbers of primates: successful long-term management of the conservation area; cessation of logging activities; a nation-wide gun confiscation program implemented in the 1990s; and habitat where there is plenty of food. The report says that the two primate populations started to recover in 2002 when the joint program between WCS and the Royal Government began and have remained stable since 2005.

The news on primates is not all good. In Cambodia, WCS researchers are concerned that looming threats could jeopardize recent successes.

"Despite this good news in Cambodia, the area still remains at risk from conversion to agro-industrial plantations for crops, including biofuels, and commercial mining," said Tom Clements, the lead author of the WCS report. "WCS is therefore committed to continuing to work with the Cambodian Government to ensure that these globally important primate populations will continue to remain secure."

WCS has worked with the Royal Government of Cambodia since 1999, helping to establish the Seima Biodiversity Conservation Area, and developing landscape-level conservation programs in the Northern Plains and Tonle Sap Great Lake.

WCS work in Cambodia has been supported by U.S. Fish and Wildlife Service's Great Apes Conservation Fund, MacArthur Foundation, Liz Claiborne Art Ortenberg Foundation, ADB Greater Mekong Subregion Core Environment Program, and the Danish Government's Danida program.

Bacteria Power

noreply@blogger.com (Surendran) — Mon, 25 Aug 2008 18:28:00 +0000

Bacteria Power: Future For Clean Energy Lies In 'Big Bang' Of Evolution

Amid mounting agreement that future clean, "carbon-neutral", energy will rely on efficient conversion of the sun's light energy into fuels and electric power, attention is focusing on one of the most ancient groups of organism, the cyanobacteria.

Dramatic progress has been made over the last decade understanding the fundamental reaction of photosynthesis that evolved in cyanobacteria 3.7 billion years ago, which for the first time used water molecules as a source of electrons to transport energy derived from sunlight, while converting carbon dioxide into oxygen.

The light harvesting systems gave the bacteria their blue ("cyano") colour, and paved the way for plants to evolve by "kidnapping" bacteria to provide their photosynthetic engines, and for animals by liberating oxygen for them to breathe, by splitting water molecules. For humans now there is the tantalising possibility of tweaking the photosynthetic reactions of cyanobacteria to produce fuels we want such as hydrogen, alcohols or even hydrocarbons, rather than carbohydrates.

Progress at the research level has been rapid, boosting prospects of harnessing photosynthesis not just for energy but also for manufacturing valuable compounds for the chemical and biotechnology industries. Such research is running on two tracks, one aimed at genetically engineering real plants and cyanobacteria to yield the products we want, and the other to mimic their processes in artificial photosynthetic systems built with human-made components. Both approaches hold great promise and will be pursued in parallel, as was discussed at a recent workshop focusing on the photosynthetic reaction centres of cyanobacteria, organised by the European Science Foundation (ESF).

A key point noted by Eva Mari Aro, the vice-chair of the ESF conference, was that there is now universal agreement over the ability of photosynthesis to provide large amounts of clean energy in future. While the sustainable options currently pursued such as wind and tidal power will meet some requirements, they will not be able to replace fossil fuels as sources of solid energy for driving engines, nor are they likely to be capable on their own of generating enough electricity for the whole planet.

Meanwhile the current generation of biofuel producing crops generally convert less than 1% of the solar energy they receive to biomass, which means they would displace too much agricultural land used for food production to be viable on a large scale. There is the potential to develop dedicated systems, whether based on cyanobacteria, plants, or artificial components, capable of much higher efficiencies, reaching 10% efficiency of solar energy conversion. This would enable enough energy and fuel to be produced for a large part of the planet's needs without causing significant loss of space for food production.

As Aro pointed out, photosynthesis evolved by cyanobacteria produced all our fossil fuels in the first place. However the rapid consumption of these fossil fuels since the industrial revolution would if continued return atmospheric carbon dioxide towards the levels at the time cyanobacteria evolved, also heating the planet up to the much higher temperatures that prevailed then.

The objective now is to exploit the same reactions so that the remaining fossil fuels can be left in the ground. Among promising contenders discussed at the ESF conference was the idea of an artificial leaf that would simulate not just photosynthesis itself but also the ability of plants to regenerate themselves. This could be important, since the reactions of photosynthesis are destructive, dismantling the protein complexes where they take place, which therefore need regular reconstruction. Under a microscope, chloroplasts, the sub-cellular units where photosynthesis take place, resemble a permanent construction site, and even artificial systems would probably need some form of regenerative capability.

A future aim therefore is to build an artificial leaf-like system comprised of self-assembling nanodevices that are capable of regenerating themselves – just as in real plants or cyanobacteria. "Fundamental breakthroughs in these directions are expected on a time scale of 10 to 20 years and are recognized by the international science community as major milestones on the road to a renewable fuel," said Aro.

Such breakthroughs depend on further progress in understanding the precise structure and mechanisms of photosynthesis, in particular the protein complex known as photosystem II, which breaks down the hydrogen atoms of water into their constituent protons and electrons to carry the energy derived from sunlight onto photosystem I, leading to production of carbohydrates and ultimately also the proteins and fats required by all organisms.

The conference "Molecular Bioenergetics of Cyanobacteria: Towards Systems Biology Level of Understanding" was held on the Costa Brava, Spain during spring 2008.

Mystery Of Young Stars Near Black Holes Solved

noreply@blogger.com (Surendran) — Sun, 24 Aug 2008 18:38:00 +0000

Mystery Of Young Stars Near Black Holes Solved

The mystery of how young stars can form within the deep gravity of black holes has been solved by a team of astrophysicists at the Universities of St Andrews and Edinburgh.

The team made the discovery after developing computer simulations of giant clouds of gas being sucked into black holes. The new research may help scientists gain better understanding of the origin of stars and supermassive black holes in our Galaxy and the Universe. The new discovery is published in the journal Science August 22, 2008.

Until now, scientists have puzzled over how stars could form around a black hole, since molecular clouds - the normal birth places of stars - would be ripped apart by the black hole's immense gravitational pull.

However, the new study by Professor Ian Bonnell (St Andrews) and Dr Ken Rice (Edinburgh) found that stars appear to form from an elliptical-shaped disc, the remnant of a giant gas cloud torn apart as it encounters a black hole.

The discovery of hundreds of young stars, of high masses and making oval-shaped orbits around a black hole three million times more massive than the sun, and at the centre of our Galaxy, is described as one of the most exciting recent discoveries in astrophysics.

Prof Bonnell comments "These simulations show that young stars can form in the neighbourhood of supermassive black holes as long as there is a reasonable supply of massive clouds of gas from further out in the Galaxy.

The simulations, performed on the Scottish Universities Physics Alliance (SUPA) SGI Altix supercomputer - taking over a year of computer time - followed the evolution of two separate giant gas clouds up to 100,000 times the mass of the sun, as they fell towards the supermassive black hole.

The simulations show how the clouds are pulled apart by the immense gravitational pull of the black hole. The disrupted clouds form into spiral patterns as they orbit the black hole; the spiral patterns remove motion energy from gas that passes close to the black hole and transfers it to gas that passes further out. This allows part of the cloud to be captured by the black hole while the rest escapes. In these conditions, only high mass stars are able to form and these stars inherit the eccentric orbits from the disc. These results match the two primary properties of the young stars in the centre of our Galaxy: their high mass and their eccentric orbits around the supermassive black hole.

Dr Rice comments " The crucial element was the modelling of the heating and cooling of the gas as this tells us how much mass is needed for part of the gas to have enough gravity to overcome its own gas pressure, and thus form a star. The heating is caused by the extreme compression of the cloud as it is squashed and pulled apart by the black hole. This is balanced by the cooling which requires detailed knowledge of how quickly the radiation can escape the cloud. "

Professor Bonnell concluded, “That the stars currently present around the Galaxy's supermassive black hole have relatively short lifetimes of ~10 million years, suggests that this process is likely to be repetitive. Such a steady supply of stars into the vicinity of the black hole, and a diet of gas directly accreted by the black hole, may help us understand the origin of supermassive black holes in our and other galaxies in the Universe."

Pangea Conundrum

noreply@blogger.com (Surendran) — Sat, 23 Aug 2008 20:13:00 +0000

The existence of the supercontinent Pangea, which formed about 300 million years ago and broke up about 200 million years ago, is a cornerstone of plate tectonics, and processes resulting in its assembly and fragmentation have governed the evolution of Earth's crust for 500 million years.

Over the past 20 years, evidence has been amassing that Pangea is just the latest in a series of supercontinents that formed repeatedly since the Archean, only to break up and reform again.

Although the mechanisms responsible are controversial, many geoscientists agree that repeated cycles of supercontinent amalgamation and dispersal have had a profound effect on the evolution of Earth's crust, atmosphere, climate, and life.

The geological record for the past one billion years is sufficiently well documented that we have a first-order picture of the changing positions of continents. Using these reconstructions in combination with other data, Murphy and Nance show that supercontinents form by different mechanisms and that many current geodynamic models cannot explain the processes that led to the amalgamation of Pangea.

These models suggest that plate tectonics is primarily driven by subduction and that supercontinents break up and migrate from sites of mantle upwelling to reassemble at sites of mantle downwelling where subduction zones exist.

Such models would predict that the young oceans created by the breakup of a supercontinent some 600 million years ago would have continued to expand as the continental fragments migrated toward sites of mantle downwelling that existed in the older ancestral Pacific Ocean. Instead, Pangea assembled as a result of the closure of the young oceans.

The geologic record suggests that there are geodynamic linkages between the younger and older oceans that deserve more detailed study; it also suggests that, in the case of Pangea, the reversal in continental motion may have coincided with emergence of a superplume 460–400 million years ago that produced mantle upwelling in the ancestral Pacific.

If so, the top-down geodynamics driven by subduction, which accounts for the assembly of the supercontinent that broke up 600 million years ago, may have been overpowered by bottom-up geodynamics involving large-scale mantle upwelling that led to the amalgamation of Pangea.

How Daughter Is Different From Mother?

noreply@blogger.com (Surendran) — Sat, 23 Aug 2008 20:08:00 +0000

How Daughter Is Different From Mother ... In Yeast Cells

The mother-daughter relationship can be difficult to understand. Why are the two so different? Now a Northwestern University study shows how this happens. In yeast cells, that is.

A research team has discovered a new mechanism for cell fate determination -- how one cell, the daughter, becomes dramatically different from the mother, even though they have the same genetic material. The study shows why mothers and daughters differ in how they express their genes.

By studying yeast, whose entire genome is known, scientists can learn the basics of cell division and apply that knowledge to the human system. Many of the fundamental mechanisms for cell division in yeast are conserved, or very similar, in mammals; many of the proteins involved in human disease are related to proteins that are involved in yeast cell division.

The new knowledge about cell fate determination could lead to a better understanding of healthy human cells, what goes awry in cancer cells and how human stem cells and germ cells work.

"Cancer may reflect a partial and aberrant loss of differentiated character, in which cells that were formerly specified to perform a specific task 'forget' that, and become more like the rapidly dividing stem cells from which they came," said Eric L. Weiss, assistant professor of biochemistry, molecular biology and cell biology in Northwestern's Weinberg College of Arts and Sciences. Weiss led the research team, which included scientists from the Massachusetts Institute of Technology.

"Understanding how differentiated states are specified might help us figure out how to remind cancer cells to go back to their original tasks or fates -- or, more likely, die."

When a yeast cell divides it produces a mother cell and a smaller, different daughter cell. The daughter cell is the one that actually performs the final act of separation, cutting its connection to the mother cell. And the daughter takes longer than the mother to begin the next cycle of division, since it needs time to grow up.

The key to the researchers' discovery of how this differentiation works is the gene regulator Ace2, a protein that directly turns genes on. The researchers found that the protein gets trapped in the nucleus of the daughter cell, turning on genes that make daughter different from mother.

The team is the first to show that the regulator is trapped because a signaling pathway (a protein kinase called Cbk1) turns on and blocks Ace2 from interacting with the cell's nuclear export machinery. Without this specific block, the machinery would move the regulator out of the nucleus, and the daughter cell would be more motherlike -- not as different.

"Daughter-cell gene expression is special, and now we know why," said Weiss.

The researchers also found that the differentiation of the mother cell and daughter cell -- this trapping of the regulator in the daughter nucleus -- occurs while the two cells are still connected.

In addition to Weiss, other authors of the paper are Emily Mazanka (lead author), Brian J. Yeh and Patrick Charoenpong, from Northwestern; and Jes Alexander, Drew M. Lowery and Michael Yaffee, from the Massachusetts Institute of Technology.

West Nile Virus In Horses

noreply@blogger.com (Surendran) — Fri, 22 Aug 2008 22:31:00 +0000

West Nile Virus In Horses

A new test for West Nile virus in horses that could be modified for use on humans and wildlife may help track the spread of the disease, according to an article in the September issue of the Journal of Medical Microbiology.

West Nile virus infects a wide range of animals, including humans, horses, dogs, cats, bats, squirrels, rabbits and birds. It is widely distributed in Africa, the Middle East and Europe. It was first reported in North America in 1999, when there were human fatalities in New York City. Since its arrival in the USA it has spread rapidly across the continent. The virus sometimes causes swelling of the brain, or encephalitis, which can be fatal. It is transmitted by several species of mosquito. Because the mosquitoes feed on so many different creatures the virus spreads quickly in areas where it has been introduced.

"Thousands of cases of West Nile virus have been reported worldwide, but 80% of infected people don't show any symptoms," said Dr Louis A Magnarelli, Director of The Connecticut Agricultural Experiment Station in the USA. "It is important to have highly sensitive and specific tests to diagnose infections and also to help track the ecology and epidemiology of West Nile encephalitis."

The US researchers have found that a new test designed to detect antibodies produced by horses is highly effective at diagnosing West Nile virus infections. Compared to the standard test for West Nile virus, the new test is much faster and gives accurate results. It was also useful in confirming past infections.

"Although the methods developed are for diagnosing West Nile virus in horses, the procedures can be easily modified to develop new antibody tests for humans and wildlife," said Dr Magnarelli. "It is essential to test wildlife for infection to determine the ecological and epidemiological aspects of West Nile virus infections in nature so that we can try to control the disease by managing mosquito populations."

Diagnosing West Nile encephalitis in ill horses helps to identify areas where the virus is spreading and to make decisions about vaccinating horses. Laboratory diagnosis can also clarify the cause of undiagnosed neurological disorders.

"We tested 43 privately owned horses for the infection. The results showed that none of the horses with undiagnosed illnesses had been infected prior to the 1999 outbreak of West Nile virus in Connecticut, USA," said Dr Magnarelli. "This kind of information is useful in confirming the epidemiology of the virus; determining when it arrived in certain areas and how it spreads."

New Mosquito Virus

noreply@blogger.com (Surendran) — Fri, 22 Aug 2008 22:25:00 +0000

Malaria Researchers Identify New Mosquito Virus

Researchers at the Johns Hopkins Bloomberg School of Public Health's Malaria Research Institute have identified a previously unknown virus that is infectious to Anopheles gambiae—the mosquito primarily responsible for transmitting malaria.

According to the researchers, the discovered virus could one day be used to pass on new genetic information to An. gambiae mosquitoes as part of a strategy to control malaria, which kills over one million people worldwide each year.

The virus, AgDNV, is a densonucleosis virus or "densovirus," which are common to mosquitoes and other insects, but do not infect vertebrate animals such as humans. Although the virus does not appear to harm the mosquitoes, the researchers determined it is highly infectious to mosquito larvae and is easily passed on to the adults.

According to Jason Rasgon, PhD, senior author of the study, the discovery came about serendipitously while the research team was conducting experiments to determine whether Wolbachia bacteria could be used to infect An. gambiae mosquito cells. During the analysis, Xiaoxia Ren, a postdoctoral fellow with Johns Hopkins Malaria Research Institute, noticed an "artifact," that appeared as a prominent band in the gel used to detect the bacteria.

"Finding artifacts such as this one during experiments is not uncommon, but we decided to investigate this one further since we kept observing it over and over. When we sequenced it we were surprised to learn that we had found a new virus," explained Rasgon, an assistant professor with the Bloomberg School's W. Harry Feinstone Department of Molecular Microbiology and Immunology.

According to Rasgon, the virus could be potentially altered to kill the mosquito or make An. gambiae incapable of transmitting malaria. To test the concept, the research team successfully used altered AgDNV to express harmless green fluorescent protein in the adult mosquitoes which could be easily spotted under the microscope.

"In theory, we could use this virus to produce a lethal toxin in the mosquito or instruct the mosquito to die after 10 days, which is before it can transmit the malaria parasite to humans. However, these concepts are many years away," said Rasgon.

Plastics Suspect In Lobster Illness

noreply@blogger.com (Surendran) — Tue, 19 Aug 2008 18:36:00 +0000

Plastics Suspect In Lobster Illness

The search for what causes a debilitating shell disease affecting lobsters from Long Island Sound to Maine has led one Marine Biological Laboratory (MBL) visiting scientist to suspect environmental alkyphenols, formed primarily by the breakdown of hard transparent plastics.

Preliminary evidence from the lab of Hans Laufer suggests that certain concentrations of alkyphenols may be interfering with the ability of lobsters to develop tough shells. Instead, the shells are weakened, leaving affected lobsters susceptible to the microbial invasions characteristic of the illness.

"Lobsters 'know' when their shell is damaged, and that's probably the reason when they have shell disease, why they molt more quickly," says Laufer, a visiting investigator at the MBL for over 20 years and professor emeritus of molecular and cell biology at the University of Connecticut. "But ultimately, they still come down with the disease. And we think the presence of alkyphenols contributes to that."

Like any crustacean, lobsters shed their shells multiple times in one lifetime. After molting, the outer skin of the soft and exposed lobster will begin to harden. It is here that Laufer thinks the alkyphenols are doing their damage. At this point, a derivative of the amino acid tyrosine, whose function is to harden the developing shell, is incorporated. It is known that alkyphenols and tyrosine are similarly shaped and Laufer suspects that the toxin may be blocking tyrosine from its normal functions. He is at MBL this summer to measure the amount of competition between the two molecules. Alkyphenols are also known to act as endocrine disruptors.

Laufer discovered the presence of alkyphenols in lobsters serendipitously while investigating a tremendous lobster die off at Long Island Sound in 1999, when shell disease, first observed in the mid-1990s, was noted to be on the rise. Although an unusually hot summer, it was also the first time New York City sprayed mosquito populations to prevent the spread of West Nile virus. Laufer, who began his career as an insect endocrinologist, suspected the toxins from the sprayings may have contributed to the lobster die off. In 2001, while searching for the mosquito toxins in lobsters, he instead found alkyphenols.

"It's a real problem," Laufer says. "Plastics last a long time, but breakdown products last even longer. Perhaps shell disease is only the tip of the iceberg of a more basic problem of endocrine disrupting chemicals in marine environments."

Solar Eclipse

noreply@blogger.com (Surendran) — Tue, 19 Aug 2008 18:33:00 +0000

Solar Eclipse On The Morning Of August 1st

On 1st August 2008 there will be a total eclipse of the Sun, visible from Canada, northern Greenland, Svalbard, the Barents Sea, Russia, Mongolia and China. From the whole of the British Isles observers will see a partial solar eclipse, with between 1/10th and 1/3rd of the Sun obscured by the Moon.

Total solar eclipses take place when the Earth, Moon and Sun are aligned and the shadow of the Moon touches the surface of the Earth. At mid-eclipse, observers within the lunar shadow briefly see totality, where the silhouette of the Moon completely covers the Sun, revealing the beautiful outer solar atmosphere or corona.

At its broadest, in this eclipse the lunar shadow is only 237 km (148 miles) wide but the shadow describes a path thousands of km long, traced out as the Earth rotates. The path begins in northeastern Canada, where observers will see the eclipse at sunrise, and then crosses northern Greenland, the Arctic, Barents Sea, Russia and Mongolia before ending in China where the eclipse is visible at sunset. On the ground the maximum duration of totality is 2 minutes 27 seconds but observers away from the centre of the track and at either end will see a significantly shorter event.

Away from the path of the total eclipse the Sun is only partly obscured by the Moon. This partial eclipse is visible across a large part of the northern hemisphere, including much of Europe and the whole of the UK, where it will take place in the morning.

In London the partial phase of the eclipse begins at 0933 BST (0833 GMT). Maximum eclipse is at 1018 BST (0918 GMT) when 12% of the Sun will be blocked. The partial eclipse ends at 1105 BST (1005 GMT).

Further north in the British Isles, observers enjoy a better view. From Edinburgh 23.5% of the Sun is covered and from Lerwick in the Shetland Isles, the Moon obscures 36% of the solar disk.

•Although eclipses of the Sun are spectacular events, they should NOT be viewed with the unaided eye except during the brief period of totality, which this time will not be visible anywhere in the UK. Looking at the partially eclipsed Sun without appropriate protection can cause serious and permanent damage to the eyes.

•The partial eclipse visible from the UK can be safely studied using purpose-designed solar filters available from reputable astronomical suppliers. Without these, the only safe ways to observe the Sun are to use a pinhole or telescope to PROJECT the Sun’s image onto card or to look at the natural dappled images under trees.

•On 1 August, some amateur astronomical societies and public observatories will be running events where members of the public can safely enjoy the eclipse.

Eye safety during solar eclipses: University of Waterloo (Ontario, Canada) Professor Ralph Chou's article on eye safety during solar eclipses:

International Space Station

noreply@blogger.com (Surendran) — Mon, 18 Aug 2008 20:07:00 +0000

International Space Station:

The International Space Station (ISS) is a joint project of five space agencies.

The ISS has seen the first space tourist, Dennis Tito, who spent 20 million USD to fly aboard a Russian supply mission and the first space wedding when Yuri Malenchenko on the station married Ekaterina Dmitriev who was in Texas..

For more information about the topic International Space Station, read the full article at Wikipedia.org, or see the following related articles:

Geosynchronous orbit — A geosynchronous orbit is a geocentric orbit that has the same orbital period as the sidereal rotation period of the Earth. It has a semi-major axis ... > read more

Mir— Mir was a highly successful Soviet (and later Russian) orbital station. It was humanity's first consistently inhabited long-term research station in ... > read more

Space debris — Space debris or orbital debris, also called space junk and space waste, are the objects in orbit around Earth created by man that no longer serve any ... > read more

Deimos (moon) — Deimos is probably an asteroid that was perturbed by Jupiter into an orbit that allowed it to be captured by Mars, though this hypothesis is still in ... > read more

X-Rays use Diamonds

noreply@blogger.com (Surendran) — Mon, 18 Aug 2008 20:05:00 +0000

X-rays Use Diamonds As Window To Center Of The Earth

Diamonds from Brazil have provided the answers to a question that Earth scientists have been trying to understand for many years: how is oceanic crust that has been subducted deep into the Earth recycled back into volcanic rocks?

A team of researchers, led by the University of Bristol, working alongside colleagues at the STFC Daresbury Laboratory, have gained a deeper insight into how the Earth recycles itself in the deep earth tectonic cycle way beyond the depths that can be accessed by drilling. The full paper on this research has been published July 31 in the scientific journal, Nature.

The Earth’s oceanic crust is constantly renewed in a cycle which has been occurring for billions of years. This crust is constantly being renewed from below by magma from the Earth’s mantle that has been forced up at mid-ocean ridges. This crust is eventually returned to the mantle, sinking down at subduction zones that extend deep beneath the continents. Seismic imaging suggests that the oceanic crust can be subducted to depths of almost 3000km below the Earth’s surface where it can remain for billions of years, during which time the crust material develops its own unique ‘flavour’ in comparison with the surrounding magmas. Exactly how this happens is a question that has baffled Earth scientists for years.

The Earth’s oceanic crust lies under seawater for millions of years, and over time reacts with the seawater to form carbonate minerals, such as limestone, When subducted, these carbonate minerals have the effect of lowering the melting point of the crust material compared to that of the surrounding magma. It is thought that this melt is loaded with elements that carry the crustal ‘flavour’.

This team of researchers have now proven this theory by looking at diamonds from the Juina area of Brazil. As the carbonate-rich magma rises through the mantle, diamonds crystallise, trapping minute quantities of minerals in the process. They form at great depths and pressures and therefore can provide clues as to what is happening at the Earth’s deep interior, down to several hundred kilometres - way beyond the depths that can be physically accessed by drilling. Diamonds from the Juina area are particularly renowned for these mineral inclusions.

At the Synchrotron Radiation Source (SRS) at the STFC Daresbury Laboratory, the team used an intense beam of x-rays to look at the conditions of formation for the mineral perovskite which occurs in these diamonds but does not occur naturally near the Earth’s surface. With a focused synchrotron X-ray beam less than half the width of a human hair, they used X-ray diffraction techniques to establish the conditions at which perovskite is stable, concluding that these mineral inclusions were formed up to 700km into the Earth in the mantle transition zone.

These results, backed up by further experiments carried out at the University of Edinburgh, the University of Bayreuth in Germany, and the Advanced Light Source in the USA, enabled the research team to show that the diamonds and their perovskite inclusions had indeed crystallised from very small-degree melts in the Earth’s mantle. Upon heating, oceanic crust forms carbonatite melts, super-concentrated in trace elements with the ‘flavour’ of the Earth’s oceanic crust. Furthermore, such melts may be widespread throughout the mantle and may have been ‘flavouring’ the mantle rocks for a very long time.

Dr Alistair Lennie, a research scientist at STFC Daresbury Laboratory, said: “Using X-rays to find solutions to Earth science questions is an area that has been highly active on the SRS at Daresbury Laboratory for some time. We are very excited that the SRS has contributed to answering such long standing questions about the Earth in this way.”

Dr. Michael Walter, Department of Earth Sciences, University of Bristol, said: "The resources available at Daresbury’s SRS for high-pressure research have been crucial in helping us determine the origin of these diamonds and their inclusions."

Antibacterial Pollution

noreply@blogger.com (Surendran) — Sat, 16 Aug 2008 20:28:00 +0000

Antibacterial Pollution

Introduction

A lot of household products nowadays claim to be antibacterial—containing compounds that kill viruses, bacteria, and other germs on contact. But what happens to these compounds when they get washed down the drain? You'll hear one worrisome possibility in this Science Update.

Podcast
Antibacterial Pollution

Transcript
The bad side of a bug killer. I'm Bob Hirshon and this is Science Update.

If you use an antibacterial hand sanitizer, cutting board, or toothbrush, chances are it's impregnated with Triclosan. This antibacterial compound can kill germs and keep people from getting sick, but Triclosan may also have a bad side: it could harm the environment.

That's according to a new study by University of Minnesota chemist Kristopher McNeill, and his colleagues.

McNeill:
Well, what we found is that Triclosan, which is an antibacterial, when you put it in natural water and shine sunlight on it, it converts into a dioxin. And this is not necessarily something you'd like to see because dioxins have this reputation for being incredibly toxic.

McNeill says Triclosan is washed into streams and rivers through treated human waste water. He and his colleagues found that up to twelve percent of this Triclosan gets converted into a particular form of dioxin. While this form isn't that dangerous to humans, it could have disastrous effects on plants and other animals.

Now his team is looking at what happens to other common chemicals that get dumped down the drain.

McNeill:
I think this is a good example of a compound doing something maybe a little bit unexpected, and I think this is going to be a very general phenomenon. We're going to see this happening with lots of compounds.

For the American Association for the Advancement of Science, I'm Bob Hirshon.

Making Sense of the Research

The word "antibacterial" can be found on hundreds of products these days. It wasn't that long ago that soap was just soap and a sponge was a sponge. But times have changed, and "antibacterial" sells. If it's antibacterial, it must be good, right?

This is one of several studies that suggest otherwise. As the report mentions, dioxins are a serious environmental concern. There are 75 different varieties, spanning a wide range of toxicity. And while the dioxins discussed here aren't dangerous enough to harm people directly, they can wreak havoc on wildlife. Here's a short list of their possible effects on fish and other animals: reduced fertility and hatching rates, birth defects, stunted or slowed growth, cancer, anemia, brain and nerve malfunctions, and immune system problems.

Why are dioxins so problematic? One reason is that they appear to mimic the effects of certain natural hormones in animals. When exposed to the dioxin at a crucial stage of development, it's like getting an extra dose of hormone. The result can be a mixup in the animal's body formation.

This study shows that just because something is harmless in one form doesn't mean it stays harmless forever. Many other "harmless" compounds break down into nastier components over time. And this isn't the only concern that the explosion of antibacterial products has caused. Other scientists are worried that they're acting like antibiotics, and contributing to the growth and evolution of antibiotic-resistant bacteria.

But at least they kill bacteria, right? Well, maybe not. For example, some studies suggest that plain old soap disinfects just as well as antibacterial soap. That's partly because antibacterial ingredients like Triclosan can take up to two minutes to work—when was the last time you left soap on your hands for that long? And besides, a lot of diseases are caused by viruses, not bacteria, and antibacterial soaps don't do a thing against viruses.

Renewable Energy Source

noreply@blogger.com (Surendran) — Sat, 16 Aug 2008 20:24:00 +0000

Solar Collector Could Change Asphalt Roads Into Renewable Energy Source

Anyone who has walked barefoot across a parking lot on a hot summer day knows that blacktop is exceptionally good at soaking up the sun’s warmth. Now, a research team at Worcester Polytechnic Institute (WPI) has found a way to use that heat-soaking property for an alternative energy source.

Through asphalt, the researchers are developing a solar collector that could turn roads and parking lots into ubiquitous—and inexpensive–sources of electricity and hot water.

The research project, which was undertaken at the request of Michael Hulen, president of Novotech Inc. in Acton, Mass, which holds a patent on the concept of using the heat absorbed by pavements, is being directed by Rajib Mallick, associate professor of civil and environmental engineering.

On Monday, Aug. 18, 2008, team member Bao-Liang Chen, a PhD candidate at WPI, will present the results of research aimed at evaluating the potential for transforming stretches of asphalt into a cost-effective energy source at the annual symposium of the International Society for Asphalt Pavements in Zurich, Switzerland. The study looks not only at how well asphalt can collect solar energy, but at the best way to construct roads and parking lots to maximize their heat-absorbing qualities.

“Asphalt has a lot of advantages as a solar collector,” Mallick says. “For one, blacktop stays hot and could continue to generate energy after the sun goes down, unlike traditional solar-electric cells. In addition, there is already a massive acreage of installed roads and parking lots that could be retrofitted for energy generation, so there is no need to find additional land for solar farms. Roads and lots are typically resurfaced every 10 to 12 years and the retrofit could be built into that cycle. Extracting heat from asphalt could cool it, reducing the urban ‘heat island’ effect. Finally, unlike roof-top solar arrays, which some find unattractive, the solar collectors in roads and parking lots would be invisible.”

Mallick and his research team, which also includes Sankha Bhowmick of UMass, Dartmouth, studied the energy-generating potential of asphalt using computer models and by conducting small- and large-scale tests. The tests were conducted on slabs of asphalt in which were imbedded thermocouples, to measure heat penetration, and copper pipes, to gauge how well that heat could be transferred to flowing water. Hot water flowing from an asphalt energy system could be used “as is” for heating buildings or in industrial processes, or could be passed through a thermoelectric generator to produce electricity.

In the lab, small slabs were exposed to halogen lamps, simulating sunlight. Larger slabs were set up outdoors and exposed to more realistic environmental conditions, including direct sunlight and wind. The tests showed that asphalt absorbs a considerable amount of heat and that the highest temperatures are found a few centimeters below the surface. This is where a heat exchanger would be located to extract the maximum amount of energy. Experimenting with various asphalt compositions, they found that the addition of highly conductive aggregates, like quartzite, can significantly increase heat absorption, as can the application of a special paint that reduces reflection.

Finally, Mallick says the team concluded that the key to successfully turning asphalt into an effective energy generator will replacing the copper pipes used in the tests with a specially designed, highly efficient heat exchanger that soaks up the maximum amount of the heat absorbed by asphalt. “Our preliminary results provide a promising proof of concept for what could be a very important future source of renewable, pollution-free energy for our nation. And it has been there all along, right under our feet.”

Body's Circadian Clock

noreply@blogger.com (Surendran) — Sat, 16 Aug 2008 20:21:00 +0000

Snooze Button For Body's Circadian Clock

We may use the snooze button to fine-tune our sleep cycles, but our cells have a far more meticulous and refined system. Humans, and most other organisms, have 24-hour rhythms that are regulated by a precise molecular clock that ticks inside every cell.

After decades of study, researchers are still identifying all the gears involved in running this “circadian” clock and are working to put each of the molecular cogs in its place. A new study by Rockefeller University scientists now shows how two of the key molecules interact to regulate the clock’s cycle and uncovers how that switch can go haywire, identifying one potential cause of heritable sleep disorders.

Michael Young, Richard and Jeanne Fisher Professor and head of the Laboratory of Genetics, and his colleagues have shown that the circadian clock contains the equivalent of an on/off switch that’s controlled by an enzyme called doubletime. Doubletime, or DBT, was originally named for the way that mutations of the gene create flies with a fast-running clock. DBT works by attaching phosphate groups to proteins in a process called phosphorylation. And the protein it phosphorylates, called period or PER, plays a substantial role in the timing of the clock itself, regulating the activity of other genes as it cycles on and off with a 24-hour rhythm. Researchers knew DBT played a role in regulating the period protein by attaching phosphates to it. But Young’s new study shows that DBT can either suppress or activate PER, by placing phosphates at different sites.

With the discovery that DBT has not one but two separate phosphorylation targets on PER came the realization that the enzyme is acting essentially as a switch. “It’s a phosphorylation switch controlled by doubletime that determines whether the protein is active at all,” Young says. During the “off” phase, the cell churns out PER proteins that are stable but inactive, kept so by the presence of phosphate groups at that first target site. During the “on” phase, the phosphate group in the second target site activates the protein but destabilizes it so that PER is only active for a few hours. After that, the cell begins accumulating inactive protein again and the cycle begins anew.

Young and his colleagues also uncovered mutant flies with a DBT-dependent, accelerated clock: Their period proteins were missing the first target phosphorylation site that should suppress phosphorylation of their “on” switch. As a result, their period proteins never completely stabilized. “If you can’t phosphorylate the first site, you automatically skip to the second site, phosphorylate it prematurely and produce a hyperactive repressor,” Young says. “With a repressor that acts too soon and goes away too quickly, you get a short-period phenotype.” In other words, you get a fly that wakes up too soon and falls asleep too early, a fly with a fast-running clock.

Scientists have been studying human families that have members who appear to suffer from a heritable version of this short-period phenotype, termed FASPS (for Familial Advanced Sleep Phase Syndrome); these people wake up before dawn and crash before sunset. Studies of one of these families in Utah has shown a similar period protein phosphorylation defect. Now, the researchers believe that effects like those revealed by Young’s group in the fly could very well be what’s causing the fast-running clocks in people afflicted with FASPS. “Many of the features that they’re seeing in humans are consistent with what we’re finding in flies,” Young says. “So it may help us understand the human syndrome as well.”

Brain Imaging

noreply@blogger.com (Surendran) — Wed, 06 Aug 2008 18:48:00 +0000

Cool Image: Mapping Brain Differences

This image of the human brain uses colors and shapes to show neurological differences between two people. The blurred front portion of the brain, associated with complex thought, varies most between the individuals. The blue ovals mark areas of basic function that vary relatively little. Visualizations like this one are part of a project to map complex and dynamic information about the human brain, including genes, enzymes, disease states, and anatomy. The brain maps represent collaborations between neuroscientists and experts in math, statistics, computer science, bioinformatics, imaging, and nanotechnology. Courtesy of Arthur Toga, a neuroscientist at the University of California, Los Angeles, and head of the Center for Computational Biology, which is supported by the bioinformatics and computational biology component of the NIH Roadmap for Medical Research.

Smelly Lifesaver

noreply@blogger.com (Surendran) — Wed, 06 Aug 2008 18:37:00 +0000

Life-saving hydrogen sulfide...I'm Bob Hirshon and this is Science Update.

Hydrogen sulfide is responsible for the stench of rotten eggs. But it could soon be used to buy wounded soldiers precious time. According to Mark Roth of the Fred Hutchinson Cancer Research Center in Seattle, too much blood loss often leads to rapid death. That’s because when the body loses blood, it can no longer get oxygen to tissues. But he says hydrogen sulfide decreases the body’s need for oxygen, slowing down the metabolism.

MARK ROTH (Fred Hutchinson Cancer Research Center):
By slowing that rate, we can increase the length of time that is available for caregivers to help the patient.

HIRSHON:
His says rats that were administered hydrogen sulfide after losing over 60% of their blood had excellent survival rates compared to controls. He and his colleagues hope to develop a product that wounded soldiers can give themselves while awaiting treatment. I’m Bob Hirshon, for AAAS, the science society.

Mind Body Connection

noreply@blogger.com (Surendran) — Tue, 05 Aug 2008 19:01:00 +0000

Mind-Body Connection
August 4, 2008
Scientists have discovered a key to the mind-body connection.

Transcript
BOB HIRSHON (host):
Stress on your genes….I'm Bob Hirshon and this is Science Update.

We all know stress isn’t good for us, but now researchers have discovered how stress increases our vulnerability to illnesses. Immunologist Rita Effros of the David Geffen School of Medicine at UCLA says a hormone called cortisol helps us get through stressful events. But the chronic stress of modern life can keep our cortisol levels too high, and that’s bad for us.

RITA EFFROS (David Geffen School of Medicine, UCLA):
We put cortisol in a dish with human white blood cells and we measured something called telomerase. And we found that cortisol actually inhibited the white blood cells’ ability to turn on telomerase.

HIRSHON:
She says telomerase repairs the ends of chromosomes every time our cells divide. Without it, chronically stressed people are more susceptible to disease. I’m Bob Hirshon, for AAAS, the science society.

lyzazel's ex-blog: Another blogger

noreply@blogger.com (Surendran) — Tue, 05 Aug 2008 18:22:00 +0000

lyzazel's ex-blog: Another blogger

Science Update - Anti-Asthma Bug

noreply@blogger.com (Surendran) — Sun, 27 Jul 2008 18:44:00 +0000

Introduction

A common stomach bug may prevent asthma.

Podcast : Anti-Asthma Bug

Transcript

A lung-stomach connection. I'm Bob Hirshon and this is Science Update.

People with a common stomach infection called Helicobacter pylori are 40 percent less likely to get childhood asthma and allergies. This according to microbiologist Martin Blaser, chair of the New York University Department of Medicine. Blaser says that chronic Helicobacter infections were almost universal before the age of antibiotics.

Blaser:
So, as a result, we now have people—I think for the first time in human history—adults, who either have the organism or don't, and so we can measure the consequences.

The bug has already been shown to have both costs and benefits to the gastrointestinal tract. As for the asthma connection, Blaser suspects the infection keeps the immune system occupied, reducing the likelihood that it will trigger an asthma attack. I'm Bob Hirshon, for AAAS, the science society.

Making Sense of the Research

Asthma and allergies, especially in children, have steadily increased over the last several decades, and the increase can't be explained just by better reporting and more accurate diagnoses. Severe peanut allergies, for example, were very rare a few decades ago, but are now so much more common that many schools have banned peanuts completely from the premises.

However, this isn't the case in the developing world. In fact, allergies and asthma are very rare in developing countries, and continue to be. This has led many scientists to speculate on why children in industrialized countries have become so susceptible. One popular theory in recent years has been that children in modernized countries grow up in sterilized environments, relatively free of the normal environmental particles, microbes, and parasites that people living in more earthy settings are exposed to daily. As a result, the theory suggests, their immune systems aren't kept as busy as they should be, and so they mistakenly attack harmless particles, like peanuts, when given the opportunity. But this theory has some holes in it: for example, is a child in New York City really living in a more "sterile" environment than a child in the mountains of Tibet?

Now, Blaser's work suggests that asthma and allergies may, in part, be related to the absence of this stomach infection—which in turn, may be caused by antibiotics. Children today are given antibiotics for all sorts of ailments, like earaches. Every time a child takes an antibiotic, it kills not only the bacteria that are causing the infection, but other bacteria that live in the body—whether they're good or bad for you. Given enough antibiotics, some of these infections may be killed off completely, never to return.

In this case, getting rid of Helicobacter has both pros and cons. A long-term Helicobacter infection causes stomach inflammation, called gastritis, and increases your risk of getting ulcers and stomach cancer later in life. On the other hand, the infection actually reduces your risk of getting some kinds of esophageal cancer. That's because the bacteria lowers your stomach acid, making it less likely to splash into the esophagus (a condition known as acid reflux) and damage its lining.

But why the connection to allergies and asthma? Well, Blaser suspects that it's chronic, internal infections like Helicobacter—rather than environmental microbes—that have kept our immune systems busy in the past. He points out that we encounter most microbes in the environment only in passing, whereas a chronic infection is something we live with every day. That could explain why developing countries have so few allergies. And it just so happens that in parts of Asia and Africa today, 80 to 90 percent of the population is infected with Helicobacter infection.

It's important to note that while Blaser's data come from a scientific study, his explanation for the data is his own theory, based on circumstantial evidence. Nothing in the data proves that Helicobacter actually protects against allergies; it's possible that people with allergies just tend to be less susceptible to the bacteria for some other, unrelated reason. Still, it's intriguing to consider that anything in modern medicine, even accidentally eradicating a cancer-causing stomach infection, may have unintended side effects.

Now try and answer these questions:

What is Helicobacter pylori? How has its relationship to the human population changed?

What are the positives and negatives associated with a Helicobacter infection?

Do you agree with Blaser's theory? Why or why not?

Suppose a common, chronic skin infection was also shown to be protective against asthma and allergies. Would this support, or weaken, Blaser's theory? Explain why.

Science Update - Body Image

noreply@blogger.com (Surendran) — Sun, 27 Jul 2008 18:43:00 +0000

Body Image

Introduction
If you feel fat but don’t look it, there may be a good reason. Researchers in England have found that when it comes to body image, the brain has a mind of its own.

Podcast: Body Image

Transcript

How the brain sizes up the body. I'm Bob Hirshon and this is Science Update.

Whether you feel flabby or fit depends on your brain as well as your waistline. This according to neurologist Henrik Ehrsson and his colleagues at University College, London.

They stimulated the nerves in volunteers’ bodies in a way that tricked them into feeling like their waistlines were shrinking. The illusion activated a part of the subjects’ brains called the posterior parietal cortex, which integrates sensory signals from all over the body. The nerve stimulation for each person was the same, yet some experienced the shrinking sensation more strongly—and they had more activity in this part of the brain.

Ehrsson:
That suggests that two people who have identical bodies might experience their body image differently.

This may lead to a better understanding of anorexia and other body-image disorders. I'm Bob Hirshon, for AAAS, the science society.

Making Sense of the Research

When you put your hand on a hot stove, it activates heat receptors: specialized cells on the surface of your hand custom-designed to detect heat. We have receptors for pain too, and other kinds of touch. There are even receptors throughout the body that tell us how our body is oriented in space (in other words, whether our arm is up or down).

But there aren’t receptors specifically designed for detecting our body size. Yet we’re constantly judging our body size, and not just to figure out whether we’ll fit into our favorite jeans. For example, in order to reach across a table to grab a can of soda, your brain has to factor in not only how far away the soda is, but also how long your arm is.

How does the brain do it? According to this research, it looks like body size is a higher-level process than simply perceiving heat or pain. It requires the brain to consider several different streams of information, and put them all together into a coherent picture. The posterior parietal cortex is a part of the brain that does just this sort of thing. It’s the part that was activated when the subjects were confused about their body size.

The illusion that Ehrsson’s team created is called the Pinocchio Illusion, and it’s been around since the 1980’s. Here’s how it works. You put your hand on your waist and then the researcher uses a small, vibrating device to stimulate the tendon on your wrist. This creates the sensation that your wrist is flexing, even though it isn’t actually moving. As a result, your brain gets conflicting information: “My wrist is flexing but I’m not moving it.” Brains don’t like these sorts of conflicts, and they sometimes solve them by creating illusions. In this case, your brain decides that your wrist is flexing because your waist is shrinking.

Not all of Ehrsson’s subjects experienced this illusion. Of those who did, some experienced it more strongly than others. Since the input to the body was exactly the same for each person, the researchers concluded that everybody’s brain calculates our body size a little bit differently. This conclusion is supported by the fact that the stronger the illusion, the more activity there is in the brain.

It’s a long way from this study to eating disorders like anorexia, but it may help to answer an important question: why do people with eating disorders think they’re so much heavier than they actually are? Could it be that their body-size-perception system has gone awry? And if so, can the problem be fixed? It may not be easy, but it’s possible that basic research like this could someday make a real difference in patients’ lives.

Now try and answer these questions:

What’s the difference between how we perceive body size and how we perceive pain, heat, and touch?

Describe the Pinocchio Illusion. Why was it chosen for this experiment?

Suppose all the subjects experienced the illusion in the exact same way, yet brain activity during the illusion was different from person to person. How would you interpret this result?

Suppose, instead, that everyone experienced the illusion differently—some strongly, some weakly, some not at all, just as in the real experiment—but regardless, everyone’s brain activity during the illusion was identical. What would your conclusion be in this case?