February 11, 2006, 1:36 PM CT
bacteria flipping -metabolic switch
Researchers at the Carnegie Institution's Department of Plant Biology have found that photosynthetic bacteria living in scalding Yellowstone hot springs have two radically different metabolic identities. As the sun goes down, these cells quit their day job of photosynthesis and unexpectedly begin to fix nitrogen, converting nitrogen gas (N2) into compounds that are useful for cell growth. The study, published January 30 in the early online edition of the Proceedings of the National Academy of Sciences, is the first to document an organism that can juggle both metabolic tasks within a single cell at high temperatures, and also helps answer longstanding questions about how hot-spring microbial communities get essential nitrogen compounds.
Carnegie's Arthur Grossman, Devaki Bhaya, and Anne-Soisig Steunou, along with colleagues from four partner institutions*, are studying the tiny, single-celled cyanobacterium Synechococcus. Cyanobacteria evolved about three billion years ago, and are the oldest organisms on the planet that can turn solar energy and carbon dioxide into sugars and oxygen via photosynthesis. In fact, ancient cyanobacteria produced most of the oxygen that allows animals to survive on Earth.
Cyanobacteria such as Synechococcus are often found in the microbial mats that carpet hot springs, where life exists at near-boiling temperatures. These mats are highly organized communities where different organisms split up the work, with cyanobacteria serving as the main photosynthetic power plants. Microbial mats in Yellowstone National Park's Octopus Spring contain Synechococcus that can grow in waters up to around 160Â°F, while other microbes in the hot spring can tolerate temperatures that exceed 175Â°F. But until now, it was unclear which organisms could fix nitrogen-particularly in the hotter regions of the mat. ........
Posted by: Nora Permalink
February 2, 2006, 8:35 PM CT
Anthrax Toxins Harmful To Fruit Flies
Deadly and damaging toxins that allow anthrax to cause disease and death in mammals have similar toxic effects in fruit flies, as per a research studyconducted by biologists at the University of California, San Diego.
Their findings, which appear this week in an early online edition of the journal Proceedings of the National Academy of Sciences, show that fruit flies can be used to study the link between the biochemical activities and physiological effects of anthrax toxins.
Learning how these toxins attack developing and adult tissues is important because it can help researchers understand how they function at the molecular level and may lead to new therapeutic strategies for neutralizing their effects in humans.
Annabel Guichard, a biologist at UCSD and lead author of the study, tracked the ways that two active anthrax toxins, known as lethal factor, or LF, and edema factor, EF, cause cellular damage and death in the fruit fly Drosophila melanogaster. These toxins are mandatory for the anthrax bacterium Bacillus anthracis to evade the host immune system and cause disease.
Using a combination of biochemical, genetic and cell biological approaches, the biologists tested whether or not the anthrax toxins were active in living Drosophila and, if so, whether they acted in the same way as they do in humans. The biologists found that anthrax toxins do alter the same signaling pathways used for cell communication in fruit flies and humans.........
Posted by: Aaron Permalink
January 31, 2006, 0:38 AM CT
Human Embryonic Stem Cells Into Mouse Brain
Prior studies have shown that undifferentiated human embryonic stem cells (hESC) can survive in the brains of laboratory rats with Parkinson's disease. But until now it was unclear whether hESCs can become fully functional members of the host animal's neuronal architecture - a basic necessity if stem cells are ever to be used in medical therapys replenishing missing or damaged neurons in human patients with neurodegenerative diseases such as Parkinson's or Alzheimer's disease.
Now, research at the Salk Institute for Biological Studies indicates for the first time that hESCs mature into fully functional adult brain cells and integrate into the existing nervous system when these human cells are injected in the developing brains of two-week-old mouse embryos. This novel finding paves the way for a new approach to the study of neurodegenerative disorders and has the potential to speed up the testing of therapeutic drugs to treat these diseases.
The Salk scientists led by Fred H. Gage, Ph.D, professor and co-head of the Laboratory of Genetics at the Salk Institute, published their finding in this week's Proceedings of the National Academy of Science.
"Besides its therapeutic potential, our finding also opens up the possibility to study human disease in a new context," says first author Alysson R. Muotri, Ph.D. "We can ask if neurodegeneration is the function of an individual diseased cell or if it is caused by the local environment in the brain."........
Posted by: Nora Permalink
January 28, 2006, 6:16 PM CT
Proof Of Extended Magnetic Activity In Space
Writing in the journal Nature, the British, French and American team claims that these observations provide the first good evidence that a process known as 'magnetic reconnection' can occur over extended areas in space.
Magnetic reconnection is a physical process in which oppositely directed magnetic fields are annihilated and the energy stored in them is converted to beams of energetic atomic particles. This reconnection process is believed to drive the dynamics of the Earths magnetosphere and is responsible for phenomena such as solar flares and the aurora.
Until now, a full description of reconnection has proved elusive because in-situ observations were only made within the Earth's magnetosphere, the band of space surrounding Earth that protects it from most of the Sun's particles. In this area the thin electrical current sheets in which reconnection occurs extend over a short scale, allowing only evidence of patchy reconnection to be found. Researchers needed observations on a much larger scale to prove that reconnection over distances of thousands of kilometres can occur as predicted.
This evidence was provided in 2002, when the team discovered that reconnection could take place in the solar wind, a stream of particles ejected from the atmosphere of the Sun. Here, unlike in the magnetosphere, the current sheets occur over much greater distances. This gave scientists the opportunity to test the theory of large-scale reconnection.........
Posted by: Edwin Permalink
January 25, 2006, 9:15 PM CT
Discovery Of Small, Rocky, Extrasolar World
Using a relatively new planet-hunting technique that can spot worlds one-tenth the mass of our own, scientists have discovered a potentially rocky, icy body that may be the smallest planet yet found orbiting a star outside our solar system.
The discovery suggests the technique, gravitational microlensing, may be an exceptional technology for finding distant planets with traits that could support life.
"This is an important breakthrough in the quest to answer the question 'Are we alone?'" said Michael Turner, assistant director for the National Science Foundation (NSF) mathematical and physical sciences directorate. "The team has discovered the most Earth-like planet yet, and more importantly, has demonstrated the power of a new technique that is sensitive to detecting habitable planets. It can probe a much greater portion of our galaxy and is complementary to other techniques".
Located more than 20,000 light years away in the constellation Sagittarius, close to the center of our Milky Way galaxy, planet OGLE-2005-BLG-390Lb is approximately five-and-a-half times the mass of Earth.
Orbiting a star one-fifth the mass of the sun at a distance almost three times that of Earth's orbit, the newly discovered planet is frigid: the estimated surface temperature is -364 degrees Fahrenheit (-220 degrees Celsius).........
Posted by: Edwin Permalink
January 24, 2006, 4:45 PM CT
Bacterial Genome Sequenced From Ancient Salterns
Tourists in Spain often stop to ogle the country's a number of saltwater lagoons, used to produce salt since Roman times. Scientists, too, admire these saltern crystallizers-and even more so, the microbes that manage to survive in such briny environs. Now, reporting in the November 28-December 2 early online edition of the Proceedings of the National Academy of Sciences, scientists at The Institute for Genomic Research and collaborators reveal the genome of one bacterium at home in the salty Spanish ponds.
The bacterium is Salinibacter ruber , a bright red, rod-shaped organism. Several years ago, researchers first isolated S. ruber from saltern crystallizer ponds in Alicante and Mallorca , Spain. Eventhough extreme-loving microbes called archaea were known to eke out life in the ponds, researchers were surprised to discover ordinary bacteria also thriving in such a physically demanding environment, at salt concentrations up to 30 percent. How could these microbes-which normally prefer milder environments-thrive in such high salt?
To find out, TIGR scientists Emmanuel Mongodin and Karen Nelson, working with Canadian and Spanish colleagues, set out to sequence S. ruber 's genome. In doing so, the researchers discovered evidence that the resourceful bacterium independently evolved some salt-surviving biochemistry. More surprising, S. ruber apparently also borrowed some genes from neighboring archaeal species, in an unusual example of cross-domain lateral gene transfer.........
Posted by: Nora Permalink
January 24, 2006, 3:47 PM CT
Sequence Three Fungus Genomes
From garden compost to forest greenery, the mold Aspergillus fumigatus lurks across much of the world. And so does its impact. The most common mold causing infection, A. fumigatus triggers allergic reactions, asthma attacks--and even deadly infections among people with weakened immune systems.
Now, in the December 22 issue of the journal Nature, scientists at The Institute for Genomic Research (TIGR) and their collaborators report the mold's sequenced genome. The genome could lead researchers to A. fumigatus genes with the potential to generate better diagnostics and treatment for fungal infection. "This genome sequence is going to be central for developing tools for effectively managing A. fumigatus infections as they become more prevalent in the aging population," predicts first author William Nierman, a microbiologist at TIGR.
Nierman co-authored two additional Aspergillus genome papers in the same issue of Nature. One describes a genome project on Aspergillus oryzae, a nonpathogenic food industry workhorse that has produced sake (rice wine), miso (soybean paste), and shoyu (soy sauce) for 2,000 years. The third paper reports the genome sequence of model organism Aspergillus nidulans and compares the organism to A. oryzae and A. fumigatus. The work was carried out collaboratively at several institutions in the U.S., U.K., Spain, Japan, France, Brazil, Austria, Switzerland, and Germany. David Denning of the University of Manchester coordinated the projects.........
Posted by: Nora Permalink
January 18, 2006, 9:42 PM CT
New Method Developed For Exploring The Nature
Image Credit: William McConville and Ruifang Wang, Penn State
A new method for exploring the secrets of Mother Nature's frustrations has been developed by a team of physicists lead by Penn State University professors Peter Schiffer, Vincent Crespi, and Nitin Samarth. The research, which will be published this week in the journal Nature, is an important contribution to the study of complex interacting systems, and it also could contribute to technologies for advanced magnetic-recording devices.
"We all would prefer to have less personal experience with frustration, but the state of frustration also is an important factor in the way a number of systems in nature work," explains Schiffer, who is a professor of physics at Penn State. "Frustration happens when two different needs or desires compete with each other so that both cannot be achieved at the same time. This kind of frustration happens in our brain, in proteins, and in a number of other areas of the natural world, where networks of a number of different components must interact with each other to achieve a complex end".
Schiffer explains, for example, that neural networks, which allow the brain to function, and protein molecules, which allow living matter to function, consist of thousands to millions of interacting components, and that a crucial element of these interactions is that they often are "frustrated." "When two different and competing signals are sent in the brain, the brain needs to choose which signal will dominate in order to take a particular action," Schiffer says. "Frustration happens even in a simple substance such as ice, which consists of only hydrogen and oxygen atoms, because there are competing forces on the hydrogen atoms pushing them between different positions relative to their neighboring oxygen atoms," he explains.........
Posted by: Jaison Permalink
January 18, 2006, 9:37 PM CT
Size of a Small, Frost World
Observing a very rare occultation of a star by Pluto's satellite Charon from three different sites, including Paranal, home of the VLT, astronomers were able to determine with great accuracy the radius and density of the satellite to the farthest planet. The density, 1.71 that of water, is indicative of an icy body with about slightly more than half of rocks. The observations also put strong constraints on the existence of an atmosphere around Charon.
Since its discovery in 1978, Charon and Pluto have appeared to form a double planet, rather than a planet-satellite couple. Actually, Charon is about twice as small as Pluto in size, and about eight times less massive. However, there have been considerable discussions concerning the precise radii of Pluto and Charon, as well as about the presence of a tenuous atmosphere around Charon.
In August 2004, Australian amateur astronomer Dave Herald predicted that the 15-magnitude star UCAC2 26257135 should be occulted by Charon on 11 July 2005. The occultation would be observable from some parts of South America, including Cerro Paranal, in the northern Atacama Desert, the location of ESO's Very Large Telescope (VLT).
Stellar occultations have proved to be powerful tools to both measure sizes - at km-level accuracy, i.e. a factor ten better than what is feasible with other techniques - and detect very tenuous atmosphere - at microbar levels or less. Unfortunately, in the case of Charon, such occultations are extremely rare, owing to the very small angular diameter of the satellite on the sky: 55 milli-arcsec, i.e. the size of a one Euro coin observed from 100 km away!.........
Posted by: Brooke Permalink
January 17, 2006, 0:22 AM CT
German Technology for Hubble's Successor
Carl Zeiss Optronics, in Oberkochen, Gera number of, and the Max Planck Institute for Astronomy in Heidelberg (MPIA), are developing the main fine mechanical optical technology for two instruments to be part of the James Webb Space Telescope (JWST). Over the next eight years, under administration of the European Space Agency and NASA in the USA, the JWST (with a mirror of 6.5 metres) will shape up to be the successor to the legendary HUBBLE Space Telescope. Carl Zeiss and the Max Planck Institute signed a contract on November 29 to co-operate in their work on the MIRI and NIRSpec instrumentation of the JWST.
The JAMES WEBB Space Telescope is going to replace the Hubble Space Telescope in the next few decades as the most important tool for astronomical observation. The most important scientific goal of the mission is to discover the "first light" of the early universe - the formation of the first stars out of the slowly cooling Big Bang. The light from these first stars and galaxies has shifted into the infrared spectrum because its wavelength has stretched out some twenty times, as the universe has been expanding. The infrared (warm) radiation of the telescope and its instruments could disturb these weak cosmic signals. In order to prevent this, the telescope has to be essentially deep frozen.........
Posted by: Jaison Permalink
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