Science Signaling | Year: 2011
As one of the largest and most extensively therapeutically targeted class of receptors, G protein-coupled receptors (also known as seven transmembrane receptors) are clinically important regulators of physiology. Research highlighted in this issue of Science Signaling provides insight into how receptor phosphorylation enables agonists to trigger distinct cellular responses and how mutations associated with disease affect receptor responsiveness to ligands. This research helps reveal how signaling by these receptors is encoded and decoded to produce ligand-specific, cell-specific, and genome-specific responses. Source
Science Signaling | Year: 2011
Phosphoproteomic analysis of mammalian or yeast cells arrested in mitosis provides a comprehensive view of how phosphorylation contributes to this process, and the research highlighted in this issue implicates previously unrecognized players in this complex process of cell division. Analysis of substrate selectivity and the motifs targeted by specific kinases suggests that cells combine negative and positive site selection, along with spatial segregation, to ensure that the multiple kinases that participate in mitosis find their proper targets. Because alterations in the activities of these kinases can lead to uncontrolled cell proliferation and because of their essential roles in regulating cell division, these kinases are the targets of anticancer therapeutic agents. The research highlighted in this issue not only provides rich data sets for future investigation, but also has the potential to lead to the development of new treatments aimed at reining in uncontrolled cell proliferation. Source
News Article | September 6, 2016
A White House panel of experts, including federal judges, are recommending that some forensic disciplines be thrown out of courtrooms, while some others need further scientific validation. The report, approved last Thursday by the President’s Council of Advisors on Science and Technology, blasts some analyses that have drawn recent scrutiny, including bite marks and hair follicles. But the report also contends that the culture needs to change to focus on fact-finding in the laboratory – and not on-the-job experience during criminal investigations, a Forensic Magazine review of the document found. “Casework is not scientifically valid research, and experience alone cannot establish scientific validity,” the report states. “In particular, one cannot reliably estimate error rates from casework because one typically does not have independent knowledge of the ‘ground truth’ or ‘right answer.’” The group included nine federal judges, a former U.S. Solicitor General, a state supreme court justice, law school deans, and statisticians. Overall, they concluded that forensic science results be “repeatable, reproducible and accurate.” The panel held a massive 2002 FBI study of the hair analysis as a “landmark of forensic science,” due to its scientific standards. That study eventually led to reconsideration of tens of thousands of criminal convictions – but only after more than a decade had elapsed. The group also recommended that the FBI Laboratory assume more of a lead role in the ongoing “overhaul” of the forensic science, through training, research, and validation of existing and future technologies. More government funding should be directed to agencies to further forensic scientific study, they added. “The total level of federal funding by NIJ, NIST and NSF to the academic community for fundamental research in forensic science is extremely small,” they write. “Substantially larger funding will be needed to develop a robust research community and to support the development and evaluation of promising new technologies.” Forensic science, which has captured the imagination of the public in the 21st century with the popularization of TV shows like CSI, first came under widespread scrutiny in 2009, with a report by National Research Council entitled “Strengthening Forensic Science in the United States: A Path Forward.” It called for major reforms to the criminal-justice system – and to establish national forensics scientific standards. The American Association for the Advancement of Science has undertaken what could become a “transformational” reevaluation of American forensic science, in response to the 2009 report. Ten disciplines are going to be subject to investigation. First up is ballistics and tool markers, latent fingerprints and arson investigations. Those are already underway. The next seven are: bloodstain pattern analysis, digital evidence, footwear and tire tracks, bitemark analysis, fiber trace evidence, hair trace evidence, and trace evidence of paint and other coatings,according to the AAAS.
News Article | April 20, 2016
There may be a remarkable potential energy future for nanotubes. Researchers at the Energy Department’s National Renewable Energy Laboratory (NREL) believe finely tuned carbon nanotube thin film has the potential to act as a thermoelectric power generator which captures and uses waste heat. According to press information, this research might help guide the manufacture of thermoelectric devices based on either single-walled carbon nanotube (SWCNT) films or composites containing these nanotubes. Because more than half of the energy consumed worldwide is rejected primarily as waste heat, the idea of thermoelectric power generation is emerging as a potentially important part of renewable energy portfolios. Then there is the emerging and expanding field of energy efficiency. “There have not been many examples where people have really looked at the intrinsic thermoelectric properties of carbon nanotubes and that’s what we feel this paper does,” said Andrew Ferguson, a research scientist in NREL’s Chemical and Materials Science Center and co-lead author of the paper with Jeffrey Blackburn. The research, “Tailored Semiconducting Carbon Nanotube Networks with Enhanced Thermoelectric Properties,” appears in the journal Nature Energy. The research represents a collaboration between : As reported in EurekAlert, nanostructured inorganic semiconductors have demonstrated promise for improving the performance of thermoelectric devices. “Inorganic materials can run into problems when the semiconductor needs to be lightweight, flexible, or irregularly shaped because they are often heavy and lack the required flexibility. Carbon nanotubes, which are organic, are lighter and more flexible. ‘How useful a particular SWCNT is for thermoelectrics, however, depends on whether the nanotube is metallic or a semiconductor, both of which are produced simultaneously in SWCNT syntheses. A metallic nanotube would harm devices such as a thermoelectric generator, whereas a semiconductor nanotube actually enhances performance. Furthermore, as with most optical and electrical devices, the electrical band gap of the semiconducting SWCNT should affect the thermoelectric performance as well.” Blackburn, a senior scientist and manager of NREL’s Spectroscopy and Photoscience group, has developed an expertise at separating semiconducting nanotubes from metallic ones. His methods were critical to the research, Ferguson said. “We are at a distinct advantage here that we can actually use that to probe the fundamental properties of the nanotubes,” he said. Further information on this valuable research endeavor is available at this AAAS story. Drive an electric car? Complete one of our short surveys for our next electric car report. Keep up to date with all the hottest cleantech news by subscribing to our (free) cleantech newsletter, or keep an eye on sector-specific news by getting our (also free) solar energy newsletter, electric vehicle newsletter, or wind energy newsletter.
Abstract: Bacteria are the most abundant form of life on Earth, and they are capable of living in diverse habitats ranging from the surface of rocks to the insides of our intestines. Over millennia, these adaptable little organisms have evolved a variety of specialized mechanisms to move themselves through their particular environments. In two recent Caltech studies, researchers used a state-of-the-art imaging technique to capture, for the first time, three-dimensional views of this tiny complicated machinery in bacteria. Credit: Science/AAAS "Bacteria are widely considered to be 'simple' cells; however, this assumption is a reflection of our limitations, not theirs," says Grant Jensen, a professor of biophysics and biology at Caltech and an investigator with the Howard Hughes Medical Institute (HHMI). "In the past, we simply didn't have technology that could reveal the full glory of the nanomachines--huge complexes comprising many copies of a dozen or more unique proteins--that carry out sophisticated functions." Jensen and his colleagues used a technique called electron cryotomography to study the complexity of these cell motility nanomachines. The technique allows them to capture 3-D images of intact cells at macromolecular resolution--specifically, with a resolution that ranges from 2 to 5 nanometers (for comparison, a whole cell can be several thousand nanometers in diameter). First, the cells are instantaneously frozen so that water molecules do not have time to rearrange to form ice crystals; this locks the cells in place without damaging their structure. Then, using a transmission electron microscope, the researchers image the cells from different angles, producing a series of 2-D images that--like a computed tomography, or CT, scan--can be digitally reconstructed into a 3-D picture of the cell's structures. Jensen's laboratory is one of only a few in the entire world that can do this type of imaging. In a paper published in the March 11 issue of the journal Science, the Caltech team used this technique to analyze the cell motility machinery that involves a structure called the type IVa pilus machine (T4PM). This mechanism allows a bacterium to move through its environment in much the same way that Spider-Man travels between skyscrapers; the T4PM assembles a long fiber (the pilus) that attaches to a surface like a grappling hook and subsequently retracts, thus pulling the cell forward. Although this method of movement is used by many types of bacteria, including several human pathogens, Jensen and his team used electron cryotomography to visualize this cell motility mechanism in intact Myxococcus xanthus--a type of soil bacterium. The researchers found that the structure is made up of several parts, including a pore on the outer membrane of the cell, four interconnected ring structures, and a stemlike structure. By systematically imaging mutants, each of which lacked one of the 10 T4PM core components, and comparing these mutants with normal M. xanthus cells, they mapped the locations of all 10 T4PM core components, providing insights into pilus assembly, structure, and function. "In this study, we revealed the beautiful complexity of this machine that may be the strongest motor known in nature. The machine lets M. xanthus, a predatory bacterium, move across a field to form a 'wolf pack' with other M. xanthus cells, and hunt together for other bacteria on which to prey," Jensen says. Another way that bacteria move about their environment is by employing a flagellum--a long whiplike structure that extends outward from the cell. The flagellum is spun by cellular machinery, creating a sort of propeller that motors the bacterium through a substrate. However, cells that must push through the thick mucus of the intestine, for example, need more powerful versions of these motors, compared to cells that only need enough propeller power to travel through a pool of water. In a second paper, published in the online early edition of the Proceedings of the National Academy of Sciences (PNAS) on March 14, Jensen and his colleagues again used electron cryotomography to study the differences between these heavy-duty and light-duty versions of the bacterial propeller. The 3-D images they captured showed that the varying levels of propeller power among several different species of bacteria can be explained by structural differences in these tiny motors. In order for the flagellum to act as a propeller, structures in the cell's motor must apply torque--the force needed to cause an object to rotate--to the flagellum. The researchers found that the high-power motors have additional torque-generating protein complexes that are found at a relatively wide radius from the flagellum. This extra distance provides greater leverage to rotate the flagellum, thus generating greater torque. The strength of the cell's motor was directly correlated with the number of these torque-generating complexes in the cell. "These two studies establish a technique for solving the complete structures of large macromolecular complexes in situ, or inside intact cells," Jensen says. "Other structure determination methods, such as X-ray crystallography, require complexes to be purified out of cells, resulting in loss of components and possible contamination. On the other hand, traditional 2-D imaging alone doesn't let you see where individual protein pieces fit in the complete structure. Our electron cryotomography technique is a good solution because it can be used to look at the whole cell, providing a complete picture of the architecture and location of these structures." ### The work involving the type IVa pilus machinery was published in a Science paper titled "Architecture of the type IVa pilus machine." First author Yi-Wei Chang is a research scientist at Caltech; additional coauthors include collaborators from the Max Planck Institute for Terrestrial Microbiology, in Marburg, Germany, and from the University of Utah. The study was funded by the National Institutes of Health (NIH), HHMI, the Max Planck Society, and the Deutsche Forschungsgemeinschaft. Work involving the flagellum machinery was published in a PNAS paper titled "Diverse high-torque bacterial flagellar motors assemble wider stator rings using a conserved protein scaffold." Additional coauthors include collaborators from Imperial College London; the University of Texas Southwestern Medical Center; and the University of Wisconsin-Madison. The study was supported by funding from the UK's Biotechnology and Biological Sciences Research Council and from HHMI and NIH. For more information, please click If you have a comment, please us. Issuers of news releases, not 7th Wave, Inc. or Nanotechnology Now, are solely responsible for the accuracy of the content.