July 30, 2007, 7:45 PM CT

Pathway To Cell Size And Division

Organisms precisely regulate cell size to ensure that daughter cells have sufficient cellular material to thrive or to create specific cell types: a tiny sperm versus a gargantuan egg for example. In single-celled organisms such as yeast and bacteria, nutrient availability is the primary determinant of cell size. In animal cells, size is controlled in large part by a molecule that senses the blood sugar-dependent hormone insulin.

Petra Levin, Ph.D., Assistant Professor of Biology at Washington University in St. Louis, and her laboratory have recently identified a trio of enzymes that act in concert to link nutrient availability to cell size in the soil bacterium Bacillus subtilis.

Levin and her lab are looking into the factors that control the timing and position of cell division in B. subtilis. B. subtilis serves as the model system for a large family of bacteria that includes the causative agents of several important diseases, including anthrax and botulism. By learning how these simple organisms regulate division, she hopes to better understand why this process goes awry in cancer cells resulting in uncontrolled growth and aberrant division.

A primary focus of the Levin lab's research is a protein called FtsZ. FtsZ is an ancestor of tubulin, the protein that is responsible for distributing duplicated chromosomes between dividing human cells. In bacteria, FtsZ forms a ring at the future division site. The FtsZ ring then recruits all other components necessary for cell division and serves as the scaffolding for the entire division process......... Posted by: Ashley      Read more         Source

July 30, 2007, 7:21 PM CT

Robotic Fin For Submarines

Inspired by the efficient swimming motion of the bluegill sunfish, MIT scientists are building a mechanical fin that could one day propel robotic submarines.

The propeller-driven submarines, or autonomous underwater vehicles (AUVs), currently perform a variety of functions, from mapping the ocean floor to surveying shipwrecks. But the MIT team hopes to create a more maneuverable, propeller-less underwater robot better suited for military tasks such as sweeping mines and inspecting harbors--and for that they are hoping to mimic the action of the bluegill sunfish.

"If we could produce AUVs that can hover and turn and store energy and do all the things a fish does, they'll be much better than the remotely operated vehicles we have now," said James Tangorra, an MIT postdoctoral associate working on the project.

The scientists chose to copy the bluegill sunfish because of its distinctive swimming motion, which results in a constant forward thrust with no backward drag. In contrast, a human performing the breaststroke inevitably experiences drag during the recovery phase of the stroke.

Tangorra and others in the Bio-Instrumentation Systems Laboratory, led by Professor Ian Hunter of the Department of Mechanical Engineering, have broken down the fin movement of the bluegill sunfish into 19 components and analyzed which ones are critical to achieving the fish's powerful forward thrust......... Posted by: Kevin      Read more         Source

July 26, 2007, 4:51 AM CT

When off-target is right on

All organisms perform intricate molecular computations to survive. Unlike man-made computer components that are meticulously ordered on a chip, the molecules that make up biological 'computers' are diffuse within the cell. Yet these must pinpoint and then bind to specific counterparts while swimming in the cells thick, erratic molecular stew something like finding a friend in a Tokyo subway station during rush hour.

In the classical view of molecular recognition, the binding molecules fit each other like a lock and key. Half a century of research has shown, however, that in numerous cases, the molecules need to deform in order to bind, as the key is not an exact fit for the molecular lock. Why would evolution choose such an inexact system".

The work of and Dr. Tsvi Tlusty and research student Yonatan Savir of the Weizmann Institutes Physics of Complex Systems Department suggests a possible answer. A simple biophysical model they developed indicates that in picking out the target molecule from a crowd of look-alikes, the recognizer has an advantage if its slightly off-target. This may appear to be counterintuitive: Why search for a key that does not match its lock exactly, and then require that the imperfect key warp its shape to fit the lock" .

The scientists model shows that the keys deformation actually helps in discerning the right target. Eventhough the energy mandatory to deform the molecular key slightly lowers the probability of its binding to the right target, it also reduces the probability that it will bind to a wrong one by quite a bit. Thus, the quality of recognition i.e. the ratio of the right to wrong binding probabilities increases......... Posted by: Jaison      Read more         Source

July 26, 2007, 4:48 AM CT

NanoWaste needs attention of EPA

he Environmental Protection Agency (EPA) must make key decisions about how to apply the two major end-of-life statutes to nanotechnology waste in order to ensure adequate oversight for these technologies, concludes a new report from the Wilson Centers Project on Emerging Nanotechnologies. However, the report notes that the Agency lacks much of the data on human health and eco-toxicity that form the basis for such determinations, creating some tough challenges ahead in EPAs decision-making process.

In addition, firms that manufacture nanomaterials, investors, and insurers should consider the new kinds of liabilities and environmental risks that may emerge as a result of the release and disposal of waste nanomaterials into the environment. The report, Where Does the Nano Go" End-of Life Regulation of Nanotechnologies, written by environmental law experts Linda Breggin and John Pendergrass of the Environmental Law Institute, was commissioned by the Project on Emerging Nanotechnologies, an initiative of the Woodrow Wilson International Center for Scholars and The Pew Charitable Trusts. The report is available online at: www.nanotechproject.org/132.

The report provides the most comprehensive analysis to date of two key EPA-administered laws that regulate the end-of-life management strategies for nanotechnology materials and products. These are the Resource Conservation and Recovery Act (RCRA), and the Comprehensive Environmental Response, Compensation and Liability Act (CERCLA), also known as the Superfund statute......... Posted by: Kevin      Read more         Source

July 23, 2007, 6:59 PM CT

spontaneous way to duplicate beauty of nature

There are a number of objects in nature, such as flowers, that are pre-programmed to develop into delicate, beautiful and intrically shaped forms. But can this pre-determined process be duplicated by man starting with plain, flat surfaces".

Yes, say Dr. Eran Sharon and his co-workers, Yael Klein and Efi Efrati, at the Hebrew University of Jerusalem Racah Institute of Physics, who have succeded for the first time anywhere in programming polymer sheets to bend and wrinkle by themselves into prescribed structures. Their work was described in the journal Science.

They made flat discs of a soft gel that, when warmed gently, curved into domes, saddles and even sombrero shapes. Such switchable shape control in a soft material could have applications ranging from optics to biomedicine.

The sheets change shape because the gel a web of cross-linked polymers shrinks at temperatures above 33 degrees celcius by an amount determined by the local polymer density.

When the density varies across the disc, the sheet buckles to relieve the pressure of uneven shrinkage. The scientists worked out what shrinkage patterns would produce the structures they wanted, then used an automated mixing system to produce cocktails of gels with the right properties......... Posted by: Kevin      Read more         Source

July 23, 2007, 6:55 PM CT

A novel molecular dictator 'with a conscience' discovered

UNSW scientists have uncovered an important naturally occurring mechanism in the body where "bad" cells that cause blockages in our blood vessels are kept under strict growth control, while "good" cells that keep our blood vessels free of clots and growths are left unaffected.

The discovery is expected to benefit those who will need heart coronary bypass surgery, an angioplasty - the mechanical widening of a narrowed or totally blocked blood vessel - or will undergo haemodialysis.

Professor Levon Khachigian, from UNSW's Centre for Vascular Research, who previously pioneered "molecular assassin" drug technology, describes this novel mechanism he discovered as "a molecular dictatorship with a conscience".

"The dictator is a specific gene suppressor called YY1, which has the therapeutically appealing capacity to differentiate between certain cell types when it goes about its activity," says Professor Khachigian.

This key finding has just been reported in the world's premier cardiovascular research journal, Circulation Research.

Professor Khachigian's research provides new hope in tackling the global problems of coronary bypass graft failure, and restenosis - the closing or narrowing of an artery that was previously opened by a procedure such as angioplasty......... Posted by: Sarah      Read more         Source

July 23, 2007, 4:59 PM CT

Spark-free, Fuel-efficient Engines

In an advance that could help curb global demand for oil, MIT scientists have demonstrated how ordinary spark-ignition automobile engines can, under certain driving conditions, move into a spark-free operating mode that is more fuel-efficient and just as clean.

The mode-switching capability could appear in production models within a few years, improving fuel economy by several miles per gallon in millions of new cars each year. Over time, that change could cut oil demand in the United States alone by a million barrels a day. Currently, the U.S. consumes more than 20 million barrels of oil a day.

The MIT team presented their latest results on July 23 at the Japan Society of Automotive Engineers (JSAE)/Society of Automotive Engineers (SAE) 2007 International Fuel and Lubricants Meeting.

A number of scientists are studying a new way of operating an internal combustion engine known as "homogeneous charge compression ignition" (HCCI). Switching a spark-ignition (SI) engine to HCCI mode pushes up its fuel efficiency.

In an HCCI engine, fuel and air are mixed together and injected into the cylinder. The piston compresses the mixture until spontaneous combustion occurs. The engine thus combines fuel-and-air premixing (as in an SI engine) with spontaneous ignition (as in a diesel engine). The result is the HCCI's distinctive feature: combustion occurs simultaneously at a number of locations throughout the combustion chamber......... Posted by: Kevin      Read more         Source

July 19, 2007, 10:43 PM CT

Rise of dinosaurs in Late Triassic more gradual

Fossils discovered in the oft-painted arroyos of northern New Mexico show for the first time that dinosaurs and their non-dinosaur ancestors lived side by side for tens of millions of years, disproving the notion that dinosaurs rapidly replaced their supposedly outmoded predecessors.

The fossils were excavated from the Hayden Quarry at Ghost Ranch, an area made famous through the paintings of Georgia O'Keefe, by a team of paleontologists from the University of California, Berkeley, the American Museum of Natural History and The Field Museum. The finds, including fossil bones of a new dinosaur predecessor the scientists have named Dromomeron romeri, are described in a cover story in the July 20 issue of Science.

"Up to now, paleontologists have thought that dinosaur precursors disappeared long before the dinosaurs appeared, that their ancestors probably were out-competed and replaced by dinosaurs and didn't survive," said co-author Kevin Padian, professor of integrative biology at UC Berkeley and a curator in the campus's Museum of Paleontology. "Now, the evidence shows that they may have coexisted for 15 or 20 million years or more".

As per primary authors Randall Irmis and Sterling Nesbitt, graduate students, respectively, at UC Berkeley and at New York's American Museum, the new bones provide anatomical information that tells paleontologists about the evolution of dinosaur precursors, their transition into true dinosaurs and how dinosaurs diversified......... Posted by: William      Read more         Source

July 19, 2007, 10:17 PM CT

Unique Volcanic Mudflow in Action in New Zealand

Volcanologist Sarah Fagents from the School of Ocean and Earth Science and Technology (SOEST) at the University of Hawaii at Manoa had an amazing opportunity to study volcanic hazards first hand, when a volcanic mudflow broke through the banks of a volcanic lake at Mount Ruapehu in New Zealand.

Fagents and his colleagues were there on a National Science Foundation (NSF)-funded project to study the long-forecast Crater Lake break-out lahar at Mount Ruapehu. A lahar is a type of mudflow composed of water and other sediment that flows down from a volcano, typically along a river valley.

Lahars are caused by the rapid melting of snow and/or glaciers during a volcanic eruption, or as in the case of Mount Ruapehu, the breakout of a volcanic lake.

"Lahars can be extremely hazardous, particularly in populated areas, because of their great speed and mass," said William Leeman, NSF program director for petrology and geochemistry. "They can flow for a number of tens of miles, causing catastrophic destruction along their path. The 1980 eruptions at Mount St. Helens, for example, resulted in spectacular lahar flows that choked virtually all drainages on the volcano, and impacted major rivers as far away as Portland, Ore".

Fagents visited stretches of the lahar pathway before the breakout to assess pre-event channel conditions. Eventhough the event was predicted to occur in 2007, the recent decreased filling rate of Crater Lake suggested that the lake bank actually would not be overtopped until 2008......... Posted by: Tyler      Read more         Source

July 19, 2007, 10:11 PM CT

Glaciers and Ice Caps to Dominate Sea Level Rise

Ice loss from glaciers and ice caps is expected to cause more global sea rise during this century than the massive Greenland and Antarctic ice sheets, as per a new University of Colorado at Boulder study.

The researcher, primarily funded by the National Science Foundation (NSF) and NASA, concluded that glaciers and ice caps are currently contributing about 60 percent of the world's ice to the oceans and the rate has been markedly accelerating in the past decade, said Emeritus Professor Mark Meier of CU-Boulder's Institute of Arctic and Alpine Research, lead study author. The contribution is presently about 100 cubic miles of ice annually -- a volume nearly equal to the water in Lake Erie -- and is rising by about three cubic miles per year.

In contrast, the CU-Boulder team estimated Greenland is now contributing about 28 percent of the total global sea rise from ice loss and Antarctica is contributing about 12 percent. Greenland is not expected to catch up to glaciers and ice caps in terms of sea level rise contributions until the end of the century, as per the study.

A paper on the subject appears in the July 19 issue of Science Express, the online edition of Science magazine. Co-authors include CU-Boulder INSTAAR scientists Mark Dyurgerov, Ursula Rick, Shad O'Neel, Tad Pfeffer, Robert Anderson and Suzanne Anderson, as well as Russian Academy of Sciences scientist Andrey Glazovsky......... Posted by: Tyler      Read more         Source