Tuesday, May 31, 2011

Scientists discover new hitch to link nerve cell motors to their cargo

from the blink of an eye to running a marathon—nerve cells transmit signals to muscle cells. To do that, nerve cells rely on tiny molecular motors to transport chemical messengers (neurotransmitters) that excite muscles cells into action. It's a complex process, which scientists are still trying to understand. A new study by Syracuse University researchers has uncovered an important piece of the puzzle.

The study, published in the April 22 issue of the (JBC), describes the discovery of a protein that is involved in the motor-cargo mechanism that carries neurotransmitter chemicals to the nerve cell's synapse. The synapse is the junction at which electrical and chemical signals are transmitted from one nerve cell to another cell. JBC is the premier journal of the American Society for Biochemistry and Molecular Biology.

The discovery was made by a team of scientists led by George M. Langford, a cell biologist and dean of SU's College of Arts and Sciences. Team members included research associate Torsten Wollert and assistant professor Michael Cosgrove in the Department of Biology; and collaborators from Dartmouth College, the Marine Biological Laboratory at Woods Hole, and the McLaughlin Research Institute. The study was funded by the National Institutes of Health.

"The transportation of neurotransmitter vesicles to the synapse is critical to nerve cell function," Langford says. "We want to better understand all of the molecular components involved in the transport process. We have discovered another 'hitch' that links the motor to its cargo."

New insights into how the chemicals are transported could result in new kinds of drug therapy for such illnesses as Parkinson's disease, depression and injuries to the neuromuscular system, Langford says.

Neurotransmitters, produced by , are used to signal cells in every organ system in the body—from muscles to metabolism. The chemicals are packaged in small sacs called synaptic vesicles. The motors transporting these vesicles are composed of a protein called myosin-Va (Myo5a). Until now, it was not clearly understood how the Myo5a motor attached to the vesicle. In a series of experiments, Langford's team demonstrated, for the first time, that Myo5a forms a complex with the protein Rab3A, which serves as the 'hitch' that snags the synaptic vesicle.

By understanding how the process works in normal cells, it's possible for scientists to find ways to turn off a malfunctioning transportation system, Langford says. For example, over-production of the neurotransmitter dopamine has been linked to depression and other mental illnesses. It may be desirable to develop drugs that prevent dopamine from being transported. Likewise preventing the transportation of muscle-contracting neurotransmitters could ease painful muscle spasms associated with Parkinson's disease and severe, nervous system injuries.

Langford's research has been dedicated to understanding how organelles move within cells. He was the first to observe the movement of synaptic vesicles on actin filaments in addition to their previously known transportation on microtubules within nerve cells. Actin filaments and microtubules are the roads on which the molecular motors transport their cargo. "Think of microtubules as the expressways in the nerve cells and the actin filaments as the local streets," Langford says.

In addition to his work on cellular transport mechanisms, Langford is researching ways to produce more effective drugs to treat Candida albicans, a fungus that causes infections in humans.

Provided by Syracuse University

Scientists uncover chemical transformations in cobalt nanoparticles

 The evolution schematics of transition from cobalt to cobalt phosphide nanocrystals.

Understanding the intricacies of how nanoparticles undergo chemical transformations could lead to better ways to tailor their composition, which can lead to advanced material properties.

Using the Cornell High Energy Synchrotron Source, scientists led by Richard Robinson, assistant professor of materials science and engineering, uncovered exactly what happens when cobalt nanoparticles transform into two phases of cobalt phosphides.

Their work, published in the , was featured by the journal as a "Hot Article" earlier this month.

The effect Robinson's team observed in the cobalt transitions was a nanoparticle hollowing due to asymmetric diffusivities of cations and anions. In other words, the cations move out from the core faster than anions can diffuse in, leading to a hollow particle.

Other groups have reported on this "Kirkendall" effect, but the Robinson team was the first to show that this hollowing is more complex than previously thought and can be studied as a two-step process. Their work could be used to control this process and produce complex particles with properties tailored for use in energy applications. Metal phosphides have a wide range of properties -- ferromagnetism, superconductivity, catalytic activity and among them.

The work was done in collaboration with scientists led by Richard Hennig, assistant professor of materials science and engineering. It was supported by King Abdullah University of Science and Technology, the Cornell Center for Materials Research and the Center at Cornell.

Provided by Cornell University (news : web)

Trash to treasure: Turning steel-mill waste into bricks

Scientists are reporting development and successful testing of a promising new way of using a troublesome byproduct of the global steel industry as raw materials for bricks that can be used in construction projects. Their study appears in ACS' Industrial & Engineering Chemistry Research.

In the report, Ana AndrĂ©s and colleagues note that steel mills around the world produce vast quantities of waste dust each year — 8 million – 12 million tons in the United States, for instance, and 700,000 tons in the European Union countries. The dust often is converted into a rock-like material known as Waelz slag, which is usually disposed of in landfills.

The slag contains iron, calcium, silicon oxide and other minor oxides as manganese, lead or zinc oxide. Scientists have been searching for practical and safe uses for Waelz slag. In earlier research, scientists showed that Waelz slag had potential as an ingredient in bricks, roof tiles and other ceramic products. The new research moves large-scale recycling of Waelz slag closer to reality, establishing at two real-world brick factories that the material can successfully be incorporated into commercial-size bricks.

It showed existing commercial equipment could be used to make bricks with Waelz slag, and eased concerns about large amounts of potentially toxic metals leaching out of such bricks. A small amount of potentially toxic material came out of the slag-made bricks over time, not in excess of European Union regulations. "Overall, it may be summarized that Waelz slag containing meet the highest quality standards set for construction ceramic materials," the researchers say.

More information: Incorporation of Waelz Slag into Commercial Ceramic Bricks: A Practical Example of Industrial Ecology, Ind. Eng. Chem. Res., 2011, 50 (9), pp 5806–5814. DOI: 10.1021/ie102145h

The recovery of electric arc furnace (EAF) dust generates large amounts of an industrial byproduct called Waelz slag. This residue, consisting primarily of iron oxide contaminated with other metal oxides (including zinc and lead), is usually disposed of in landfill sites at a high economic and environmental cost. This paper investigates an alternative based on industrial ecology principles, which involves the incorporation of Waelz slag into clay ceramic construction bricks. For the purpose of this work, Waelz slag and raw materials employed in the manufacture of ceramic bricks (natural clays, wood pulp) were characterized. Subsequently, a series of brick specimens were manufactured according to commercial mixes and using industrial equipment and procedures. Similar specimens were also produced replacing 20-30 wt % of the clay with Waelz slag. The resulting products were analyzed for their physical (bulk density, water absorption, open porosity), mechanical (modulus of rupture), and chemical properties (soluble salts content) in order to evaluate compliance with quality standards for construction materials. The environmental consequences of incorporating slag into ceramic products were also investigated at three stages of their life cycle: release of potentially toxic species during their use (NEN 7345), leaching of heavy metals after disposal in landfill sites (EN 12457 1 and 2), and emission of atmospheric pollutants during the firing process. The experimental results demonstrate that incorporation of Waelz slag does not deteriorate the physical, mechanical, and chemical properties of the resulting products. The leaching of species during its useful lives show compliance with threshold values established according to the Dutch Building Materials Decree (DBMD), and Waelz slag containing bricks fall into the category of nonhazardous waste landfill, just like conventional bricks used at this work. Emissions of CO2 and NOx were reduced versus the emissions of halogenated gases and SO2, which were favored due to the thermal decomposition of S, Cl, and F contained in the waste material.

Provided by American Chemical Society (news : web)