Max Planck Society
Max Planck Society
News Article | May 9, 2017
Researchers have identified a metabolite 'signature' that can accurately distinguish typhoid from other fever-inducing tropical diseases using patient blood samples. The research, published in the journal eLife, builds on previous results from 2014 showing that metabolite markers can distinguish between typhoid infection caused by different organisms. Many tropical diseases, such as typhoid and malaria, present with similar symptoms, making accurate diagnosis challenging and delaying effective treatment. A further problem with diagnosing typhoid is that currently available tests are not sensitive enough, and some patients are later found to have the disease, even though an organism cannot be cultured from their blood. The researchers used an approach called 'metabolomics', which involves measuring many small metabolites in a biological sample, to try and identify patterns that are unique to different diseases. In a previous study, they used this method to identify metabolic 'signatures' that could successfully differentiate between typhoid caused by two closely related organisms -- Salmonella Typhi and Salmonella Paratyphi A. "We wanted to assess if metabolomics could accurately diagnose typhoid in patients from different regions with a wider range of tropical diseases," says senior author Professor Stephen Baker, molecular microbiologist at Oxford University Clinical Research Unit, Vietnam. "We thought that this approach would more closely reflect the real situation where patients with fever-inducing diseases present with non-specific symptoms." Baker and his research collaborators collected blood samples from multiple patients from Bangladesh, who fell into three groups: patients who had Salmonella Typhi in their blood, those who were suspected of having typhoid from their symptoms, and a third group who were suspected of having a different tropical disease characterised by fever (a 'fever-control' group). Using mass spectrometry, the team analysed the metabolites in each patient blood sample to generate a metabolic 'signature' for two patient groups: those whose blood tested positive for typhoid, and fever controls. They then used this as a model to predict the identity of individual samples in a third group: patients suspected of having typhoid from their symptoms. They found that the model had excellent predictive power for distinguishing between culture-positive typhoid patients and patients with other types of tropical disease. "A major challenge in typhoid diagnosis is diagnosing true typhoid patients who have a negative blood culture result," explains first author Elin Näsström, a graduate student at Umeå University, Sweden. "We wanted to see if the detected metabolomics could help further distinguish these groups." As hoped, their predictive model pinpointed five out of nine blood-test-negative samples that were actually typhoid positive. And three out of five patients who were suspected of typhoid from their symptoms were also indicated to be typhoid-positive by their metabolite signature. To validate the signature further, the team studied an additional collection of blood samples from patients in Bangladesh and Senegal. They then compared these profiles against the original data from Nepal patients, published in the 2014 study by Näsström et al. From these combined analyses, they identified 24 metabolites that were consistently different between patients who had typhoid, and those who had other diseases including malaria. "Our results demonstrated a metabolite panel that can distinguish typhoid from other fever-inducing diseases, providing a new approach for typhoid diagnostics," Baker concludes. "The next challenges are to corroborate these metabolites in larger patient numbers and try and incorporate them into simple diagnostic test formats. This approach could be potentially expanded into other tropical diseases, eventually allowing for more accurate diagnosis and more effective treatment, and hopefully reducing the use of unnecessary antimicrobials." The paper, 'Reproducible diagnostic metabolites in plasma from typhoid fever patients in Asia and Africa', can be freely accessed online at http://dx. . It builds upon the previous study, 'Salmonella Typhi and Salmonella Paratyphi A elaborate distinct systemic metabolite signatures during enteric fever', which can be freely accessed at http://dx. . Contents, including text, figures and data, are free to reuse under a CC BY 4.0 license. eLife is a unique collaboration between the funders and practitioners of research to improve the way important research is selected, presented, and shared. eLife publishes outstanding works across the life sciences and biomedicine -- from basic biological research to applied, translational, and clinical studies. All papers are selected by active scientists in the research community. Decisions and responses are agreed by the reviewers and consolidated by the Reviewing Editor into a single, clear set of instructions for authors, removing the need for laborious cycles of revision and allowing authors to publish their findings quickly. eLife is supported by the Howard Hughes Medical Institute, the Max Planck Society, and the Wellcome Trust. Learn more at elifesciences.org. The Oxford University Clinical Research Unit (OUCRU) is a large-scale clinical and public health research unit with campuses in Ho Chi Minh City and Hanoi in Vietnam. OUCRU is hosted by the Hospital of Tropical Diseases (HTD) in Ho Chi Minh City, and the National Hospital for Tropical Diseases (NHTD) in Hanoi. As a Wellcome Trust Major Overseas Programme, OUCRU has received considerable support from the Trust since its establishment in 1991. The work of the unit covers clinical and public health research and includes work in immunology, host and pathogen genetics, molecular biology, virology, mathematical modelling, bioinformatics, biostatistics and epidemiology. Overall, OUCRU aims to have a positive and significant impact on global health and, in particular, the prevention, diagnosis and treatment of infectious diseases. This is being achieved via an integrated long-term research programme, contributions to training, the scientific literature, national and international meetings and membership of national and international committees. Priority is given to health issues important to the hospitals, and to Vietnam as a whole. All work is intended not only to benefit the patients seen daily at our host hospitals, but also to help improve patient care throughout the country. http://www.
News Article | May 10, 2017
Pro-Europe win raises scientists’ hopes Researchers in France reacted with relief and optimism to Emmanuel Macron’s sweeping victory in the country’s presidential elections on 7 May. Macron decisively defeated his far-right opponent Marine Le Pen, the leader of the Front National party, who had threatened to take France out of the European Union. The pro-European president-elect promised in his campaign to save France’s research and higher-education budgets from cuts and to launch a science-driven innovation programme to create jobs. Cap on grants The US National Institutes of Health (NIH) in Bethesda, Maryland, will limit the amount of funding that scientists supported by the agency can hold at any one time. The policy, announced on 2 May, is intended to make it easier for early- and mid-career scientists to obtain NIH grants. The agency said it will not set a hard limit on the number of grants or the amount of funding that individual researchers can receive. Instead, it will introduce a grant-support index that assigns a point value to each type of grant on the basis of its complexity and size. Currently, just 10% of grant recipients win more than 40% of the NIH’s research money. Mixed societies A total of 36 women were inducted last week into the leading scientific societies of the United States and the United Kingdom. On 2 May, the US National Academy of Sciences (NAS) announced 84 new members, 23 of whom (27%) are women. And on 5 May, the Royal Society, Britain’s oldest and most prestigious scientific society, named 13 women (26%) in its 2017 class of 50 fellows. In addition, NAS president Marcia McNutt, a geophysicist, was made a foreign member of the Royal Society. New shores David Lipman is stepping down as director of the National Center for Biotechnology Information (NCBI) in Bethesda, Maryland, the institute announced on 3 May. Lipman, who has directed the NCBI since its creation in 1988, was responsible for launching the literature database PubMed and the DNA-sequence repository GenBank, along with other public bioinformatics databases. Lipman will now serve as chief science officer at a private food-science company, Impossible Foods in Redwood City, California. Failed deal Dutch universities have failed to reach a new agreement with Oxford University Press (OUP) over access to the publisher’s academic journals. On 1 May, the Association of Universities in the Netherlands, which led the negotiations, said that the country’s research universities were unable to agree to the British publisher’s latest licensing proposal, because it did not include an offer for affordable open access to research articles in OUP journals. The Netherlands aims to make the results of all publicly funded science freely accessible by 2020. Secret mission After nearly 718 days in space, the US Air Force’s unmanned X-37B spaceplane landed at NASA’s Kennedy Space Center in Florida on 7 May. The reusable plane, which looks like a miniature space shuttle, was on an unspecified mission to carry out experiments in orbit. It was the fourth and longest flight yet for the military programme, and the first to land in Florida rather than at an Air Force base in California. DIY memo The European Centre for Disease Prevention and Control (ECDC) in Stockholm has called on European Union member states to review their procedures for authorizing do-it-yourself gene-engineering kits produced in the United States. The kits, which are intended to contain a harmless strain of the common laboratory bacterium Escherichia coli, use CRISPR precision-editing technologies and are targeted at citizen scientists. The move followed the discovery in March by German authorities that some kits had been contaminated with pathogenic bacteria, including some multidrug-resistant strains. Germany has since banned their import. The ECDC’s assessment report concluded that the risk of infection to users is low. Dead flowers A paperwork blunder has led to the accidental destruction of a valuable botanical reference collection, according to media reports. In March, biosecurity officers with the Australian quarantine authorities destroyed allegedly mislabelled samples of rare nineteenth-century daisies, which the French National Museum of Natural History in Paris had sent on loan to Brisbane. Australian authorities have asked for a review of the incident, the BBC reports. Call for diversity Canadian universities must develop plans to diversify the composition of some of their most prestigious posts, according to a requirement announced on 4 May by a trio of science-funding agencies. The new rule applies to the Can$265-million (US$194-million) Canada Research Chairs Program, which funds an estimated 1,600 professorships at Canadian higher-education institutions. By December, universities with five or more research chairs must present a plan to increase the representation of women, indigenous peoples and other minority groups, as well as people with disabilities. Progress reports are required annually, and the agencies warned that failure to fulfil the requirements could result in the withholding of funds. Advisers axed The US Environmental Protection Agency (EPA) has dismissed at least five academic researchers from a scientific advisory board. The scientists were notified on 5 May that their appointments to the 18-member Board of Scientific Counselors had expired and would not be renewed, according to media reports. An EPA official said the agency would consider replacing them with representatives from EPA-regulated industries. The US House of Representatives has also passed a Republican-sponsored bill to restructure another EPA advisory board; critics say the legislation would make it easier for industry representatives to serve. Nazi review Germany’s Max Planck Society has launched a €1.5-million (US$1.6-million), three-year study to discover as much as possible about the victims of Nazi euthanasia programmes whose brains were acquired by scientists for neuroscience research. Around 200,000 physically or mentally disabled people were murdered during the programmes. On 2 May, the society named a four-member international team that will try to identify those victims whose remains are still in Max Planck institutes and those who were interred in a special ceremony in 1990. The team will also try to reconstruct exactly what happened to the brain preparations, and how they may have been used in research and research publications. Irrational doctrine Serbia’s evolutionary society has expressed concern over a renewed attack on Charles Darwin’s theory of evolution by some 170 Serbian academics, including engineers, physicians, artists, philosophers, journalists, teachers and clergy. On 3 May, the group signed a petition to include the teaching of creationist theory in schools and universities. The academics also claim in a letter to the education and science ministry, the parliament, Serbia’s Academy of Sciences and Arts and its leading universities that Darwin’s “dogmatic” theory lacks scientific confirmation. In response, scientists with the evolutionary society said that the signatories and their creationist reasoning lack understanding of simple biology. In 2004, the Serbian education ministry had attempted in vain to ban evolutionary theory from school curricula. Charitable donations to British universities surpassed the £1-billion (US$1.3-billion) milestone for the first time last year. The 110 universities that took part in the latest Ross–CASE survey of charitable giving secured a total of £1.06 billion in philanthropic income in the academic year 2015–16. Donations were up 23% on the previous year and have almost tripled over the past 12 years. Fifty-five per cent of this income came from organizations, and 45% from individual donors. 15–16 May A Royal Society meeting in Newport Pagnell, UK, addresses how long-term climate change has affected marine palaeolandscapes. 15–19 May The International Conference on Precision Physics and Fundamental Physical Constants takes place in Warsaw.
News Article | May 18, 2017
A soft gripping system capable of strong and reversible adhesion to non-flat surfaces is particularly critical for applications in transfer printing, robotics, and precision manufacturing. In these areas, adhesion-controlled grasping of complex three-dimensional surfaces is very challenging because the adhesive must be soft enough to enable intimate contact under light pressure but stiff enough to support high load and fracture strength. "Until now, there has been a fundamental trade-off between soft, mechanically compliant interfaces and high adhesion strength," said Metin Sitti, a director in Max Planck Institute for Intelligent Systems. "With this soft gripping system, we've demonstrated that you can have both." Sitti, also an adjunct professor of mechanical engineering at Carnegie Mellon University, has long focused his research on the unique features of the gecko lizard. The gripping system contains a soft adhesive membrane with microscopic pillars that are inspired by the sticky foot hairs on a gecko's foot. The membrane is supported by a deformable gripper body that controls the gripping strength of the adhesive through changes in internal air pressure. It exhibits enhanced and robust adhesion on various sizes of curved and deformable surfaces, outperforming other adhesion methods. Another area of application for this soft gripping system is in personal robotics. "One day, we might have robots that act as assistants and care-givers—for example, a robot that can help unload a dishwater or manage medication. The ability for the robot to manipulate a broad range of objects is crucial, " said Carmel Majidi, an associate professor of mechanical engineering at Carnegie Mellon. Majidi and Sitti acknowledge Sukho Song and Dirk-Michael Drotlef in performing this multidisciplinary research and the Max Planck Society for the financial support. Majidi also acknowledges support from the Office of Naval Research. Explore further: Flexible soft gripper mimics gecko to pick up objects with curved surfaces More information: "Controllable load sharing for soft adhesive interfaces on three-dimensional surfaces," Proceedings of the National Academy of Sciences, DOI: 10.1073/pnas.1620344114
News Article | May 25, 2017
COLUMBUS, Ohio -- For the first time in history, astronomers have been able to watch as a dying star was reborn as a black hole. It went out with a whimper instead of a bang. The star, which was 25 times as massive as our sun, should have exploded in a very bright supernova. Instead, it fizzled out -- and then left behind a black hole. "Massive fails" like this one in a nearby galaxy could explain why astronomers rarely see supernovae from the most massive stars, said Christopher Kochanek, professor of astronomy at The Ohio State University and the Ohio Eminent Scholar in Observational Cosmology. As many as 30 percent of such stars, it seems, may quietly collapse into black holes -- no supernova required. "The typical view is that a star can form a black hole only after it goes supernova," Kochanek explained. "If a star can fall short of a supernova and still make a black hole, that would help to explain why we don't see supernovae from the most massive stars." He leads a team of astronomers who have been using the Large Binocular Telescope (LBT) to look for failed supernovae in other galaxies. They published their latest results in the Monthly Notices of the Royal Astronomical Society. Among the galaxies they've been watching is NGC 6946, a galaxy 22 million light-years away that is nicknamed the "Fireworks Galaxy" because supernovae frequently happen there--indeed, SN 2017eaw, discovered on May 14th, is shining near maximum brightness now. Starting in 2009, one particular star in the Fireworks Galaxy, named N6946-BH1, began to brighten weakly. By 2015, it appeared to have winked out of existence. The astronomers aimed the Hubble Space Telescope at the star's location to see if it was still there but merely dimmed. They also used the Spitzer Space Telescope to search for any infrared radiation emanating from the spot. That would have been a sign that the star was still present, but perhaps just hidden behind a dust cloud. All the tests came up negative. The star was no longer there. By a careful process of elimination, the researchers eventually concluded that the star must have become a black hole. It's too early in the project to know for sure how often stars experience massive fails, but Scott Adams, a former Ohio State student who recently earned his Ph.D. doing this work, was able to make a preliminary estimate. "N6946-BH1 is the only likely failed supernova that we found in the first seven years of our survey. During this period, six normal supernovae have occurred within the galaxies we've been monitoring, suggesting that 10 to 30 percent of massive stars die as failed supernovae," he said. "This is just the fraction that would explain the very problem that motivated us to start the survey." To study co-author Krzystof Stanek, the really interesting part of the discovery is the implications it holds for the origins of very massive black holes -- the kind that the LIGO experiment detected via gravitational waves. (LIGO is the Laser Interferometer Gravitational-Wave Observatory.) It doesn't necessarily make sense, said Stanek, professor of astronomy at Ohio State, that a massive star could undergo a supernova -- a process which entails blowing off much of its outer layers -- and still have enough mass left over to form a massive black hole on the scale of those that LIGO detected. "I suspect it's much easier to make a very massive black hole if there is no supernova," he concluded. Adams is now an astrophysicist at Caltech. Other co-authors were Ohio State doctoral student Jill Gerke and University of Oklahoma astronomer Xinyu Dai. Their research was supported by the National Science Foundation. The Large Binocular Telescope is an international collaboration among institutions in the United Sates, Italy and Germany. The LBT Corporation partners are: the University of Arizona on behalf of the Arizona University System; the Instituto nazionale di Astrofisica, Italy; the LBT Beteiligungsesellschaft, Germany, representing the Max Planck Society, the Astrophysical Institute of Potsdam and Heidelberg University; Ohio State University; and the Research Corporation, on behalf of the University of Notre Dame, University of Minnesota and University of Virginia.
News Article | April 17, 2017
Scientists have uncovered how our ancestors may have wiped out an ancient retrovirus around 11 million years ago. Retroviruses, which include human immunodeficiency virus (HIV), are abundant in nature. Unlike other viruses, which do not usually leave a physical trace of their existence, retroviruses include a step in their life cycle where their genetic material is integrated into the genome of their host. This integration has created a genetic fossil record of extinct retroviruses that is preserved in the genomes of modern organisms. Writing in the journal eLife, researchers from the Rockefeller University and the Howard Hughes Medical Institute (HHMI), US, set out to discover how extinct viral lineages could have been eliminated. To do this, they analysed retroviral fossils left by human endogenous retrovirus T (HERV-T), which replicated in our primate ancestors for approximately 25 million years before it was eradicated about 11 million years ago. Working with Robert Gifford from the University of Glasgow, the team first compiled a near-complete catalog of HERV-T fossils in old-world monkey and ape genomes. They then reconstructed the HERV-T retrovirus' outer envelope protein - a type of protein that allows a virus particle to bind to cells and begin the viral replication cycle. "Our analyses first suggested that HERV-T likely used a cell-surface protein called MCT-1 to bind to cells and infect ancient old-world primates," says first author Daniel Blanco-Melo, who carried out the study at the Rockefeller University but is now a postdoctoral researcher at the Icahn School of Medicine at Mount Sinai, New York. "Next, we identified one particular fossilised HERV-T gene in the human genome that encodes an unexpectedly well-preserved envelope protein. This gene was absent in non-hominid primate genomes, but was integrated into an ancestral hominid genome around 13 to 19 million years ago. We believe its function may have been switched around this time so that it could block infection by causing MCT-1 depletion from cell surfaces." Taken together, these findings suggest a scenario in which HERV-T began to infiltrate primate germlines (series of cells that are seen as continuing through successive generations of an organism) using MCT-1 as a receptor. Ancestral hominids later evolved a defence mechanism whereby they switched a HERV-T gene to serve as an antiviral gene against itself. "Broadly speaking, this study shows how analysing viral fossils can provide a wealth of insight into events that occurred in the distant past," says senior author Paul Bieniasz, HHMI Investigator and Professor of Retrovirology at the Rockefeller University. "In particular, it represents an example of how viruses themselves can provide the genetic material that animals use to combat them, sometimes leading to their own extinction." The paper 'Co-option of an endogenous retrovirus envelope for host defense in hominid ancestors' can be freely accessed online at http://dx. . Contents, including text, figures and data, are free to reuse under a CC BY 4.0 license. eLife is a unique collaboration between the funders and practitioners of research to improve the way important research is selected, presented, and shared. eLife publishes outstanding works across the life sciences and biomedicine -- from basic biological research to applied, translational, and clinical studies. All papers are selected by active scientists in the research community. Decisions and responses are agreed by the reviewers and consolidated by the Reviewing Editor into a single, clear set of instructions for authors, removing the need for laborious cycles of revision and allowing authors to publish their findings quickly. eLife is supported by the Howard Hughes Medical Institute, the Max Planck Society, and the Wellcome Trust. Learn more at elifesciences.org.
News Article | May 3, 2017
Adolf Hitler's so-called "euthanasia" programme, in which doctors and scientists actively participated, sought to exterminate the sick, the physically and mentally disabled, those with learning disabilities and those considered social "misfits" (AFP Photo/) Berlin (AFP) - A German network of leading science institutes will begin identifying thousands of brain specimens belonging to people killed by the Nazis because they suffered from a disability or were ill. The three-year-long research project into the human remains in the Max Planck institutes' possession will begin in June, and aims to build a database listing the names of all "euthanasia" victims. "It will include basic biographical data on the victims, their institutional treatment, and the criteria used to select the victims," the Munich-based, non-profit Max Planck Society said in a statement. "The manner of their death will also be documented along with data on the removal of the brain... and the research carried out on (it)." Adolf Hitler's so-called "euthanasia" programme, in which doctors and scientists actively participated, sought to exterminate the sick, the physically and mentally disabled, those with learning disabilities and those considered social "misfits". Between January 1940 and August 1941, doctors systematically gassed more than 70,000 people at six sites in German-controlled territory, until public outrage forced them to end the overt killing. But tens of thousands more died across Europe until the Nazis were defeated in 1945, through starvation, neglect or deliberate overdoses administered by caregivers. Many also underwent bizarre medical experiments and forced sterilisations because of their supposed genetic inferiority. Following years of lobbying by relatives and concerned citizens, Germany in 2014 inaugurated a central memorial to the victims in Berlin. During Nazi rule, the Kaiser Wilhelm scientific institutes (KWI) -- which later came under the Max Planck umbrella -- were involved in the experiments or received remains of these victims from death camps including Auschwitz for their research. Between 1940 and 1945, the KWI for Brain Research in Berlin examined around 700 brains taken from mentally ill and mentally disabled victims of the Nazi euthanasia programme. In the decades following the war, the scientists largely continued using such remains for research. "The vast majority of scientists had too little or no moral concerns about using the specimens," said Max Planck. It was only in 1989 that Max Planck decided to inter all human remains belonging to victims of the Nazis in its possession. But it later emerged that not all institutes within the grouping complied with the decision to also bury those specimens whose origins could not be clearly traced to the Nazi regime. While the institute for brain research decided to part with all specimens dating from between 1933 and 1945, the institute of psychiatry only removed items "which were unambiguously documented as victim-derived or whose origins were uncertain -- around 30 percent of the overall inventory". In 2015, a new employee at the archives in Berlin stumbled across a shoebox-sized wooden box containing slides with brain sections. The find led to further investigations which turned up "additional brain sections and preserved specimens", said Max Planck. The psychiatry institute then commissioned an external specialist to draw up a rough inventory outlining the historical documents and brain sections in its storage facilities. Completed in February 2017, the inventory lists 24,500 specimens from the 1920s through to the 1980s and serves as preparation for the identification project. Researchers will examine medical records as well as other documents linked to the specimens within the institutes. They will also look at records from the hospitals and headquarters of the Nazi "euthanasia programme" to identify which of the KWIs were involved, and which of them received brains or brain samples. Underlining the Herculean task ahead, the project's researchers acknowledged that "it will not be possible in the course of this project to undertake a more extensive reconstruction of every victim's biography in view of the large numbers of victims -- of whom there may potentially be several thousand". "It would appear realistic at best to recreate the life stories of just a few by way of example," they added. The non-governmental Max Planck Society, with an annual budget of 1.8 billion euros ($2.0 billion), operates more than 80 research institutes.
News Article | April 17, 2017
Liquid droplets are natural magnifiers. Look inside a single drop of water, and you are likely to see a reflection of the world around you, close up and distended as you’d see in a crystal ball. Researchers at MIT have now devised tiny “microlenses” from complex liquid droplets comparable in size to the width of a human hair. They report the advance this week in the journal Nature Communications. Each droplet consists of an emulsion, or combination of two liquids, one encapsulated in the other, similar to a bead of oil within a drop of water. Even in their simple form, these droplets can magnify and produce images of surrounding objects. But now the researchers can also reconfigure the properties of each droplet to adjust the way they filter and scatter light, similar to adjusting the focus on a microscope. The scientists used a combination of chemistry and light to precisely shape the curvature of the interface between the internal bead and the surrounding droplet. This interface acts as a kind of internal lens, comparable to the compounded lens elements in microscopes. “We have shown fluids are very versatile optically,” says Mathias Kolle, the Brit and Alex d'Arbeloff Career Development Assistant Professor in MIT’s Department of Mechanical Engineering. “We can create complex geometries that form lenses, and these lenses can be tuned optically. When you have a tunable microlens, you can dream up all sorts of applications.” A double-emulsion droplet switches from one conformation that focuses light, to another that scatters light. (Courtesy of the researchers) For instance, Kolle says, tunable microlenses might be used as liquid pixels in a three-dimensional display, directing light to precisely determined angles and projecting images that change depending on the angle from which they are observed. He also envisions pocket-sized microscopes that could take a sample of blood and pass it over an array of tiny droplets. The droplets would capture images from varying perspectives that could be used to recover a three-dimensional image of individual blood cells. “We hope that we can use the imaging capacity of lenses on the microscale combined with the dynamically adjustable optical characteristics of complex fluid-based microlenses to do imaging in a way people have not done yet,” Kolle says. Kolle’s MIT co-authors are graduate student and lead author Sara Nagelberg, former postdoc Lauren Zarzar, junior Natalie Nicolas, former postdoc Julia Kalow, research affiliate Vishnu Sresht, professor of chemical engineering Daniel Blankschtein, professor of mechanical engineering George Barbastathis, and John D. MacArthur Professor of Chemistry Timothy Swager. Moritz Kreysing and Kaushikaram Subramanian of the Max Planck Institute of Molecular Cell Biology and Genetics are also co-authors. The group’s work builds on research by Swager’s team, which in 2015 reported a new way to make and reconfigure complex emulsions. In particular, the team developed a simple technique to make and control the size and configuration of double emulsions, such as water that was suspended in oil, then suspended again in water. Kolle and his colleagues used the same techniques to make their liquid lenses. They first chose two transparent fluids, one with a higher refractive index (a property that relates to the speed at which light travels through a medium), and the other with a lower refractive index. The contrast between the two refractive indices can contribute to a droplet’s focusing power. The researchers poured the fluids into a vial, heated them to a temperature at which the fluids would mix, then added a water-surfactant solution. When the liquids were mixed rapidly, tiny emulsion droplets formed. As the mixture cooled, the fluids in each of the droplets separated, resulting in droplets within droplets. To manipulate the droplets’ optical properties, the researchers added certain concentrations and ratios of various surfactants — chemical compounds that lower the interfacial tension between two liquids. In this case, one of the surfactants the team chose was a light-sensitive molecule. When exposed to ultraviolet light this molecule changes its shape, which modifies the tension at the droplet-water interfaces and the droplet’s focusing power. This effect can be reversed by exposure to blue light. “We can change focal length, for example, and we can decide where an image is picked up from, or where a laser beam focuses to,” Kolle says. “In terms of light guiding, propagation, and tailoring of light flow, it’s really a good tool.” Kolle and his colleagues tested the properties of the microlenses through a number of experiments, including one in which they poured droplets into a shallow plate, placed under a stencil, or “photomask,” with a cutout of a smiley face. When they turned on an overhead UV lamp, the light filtered through the holes in the photomask, activating the surfactants in the droplets underneath. Those droplets, in turn, switched from their original, flat interface, to a more curved one, which strongly scattered light, thereby generating a dark pattern in the plate that resembled the photomask’s smiley face. The researchers also describe their idea for how the microlenses might be used as pocket-sized microscopes. They propose forming a microfluidic device with a layer of microlenses, each of which could capture an image of a tiny object flowing past, such as a blood cell. Each image would be captured from a different perspective, ultimately allowing recovery of information about the object’s three-dimensional shape. “The whole system could be the size of your phone or wallet,” Kolle says. “If you put some electronics around it, you have a microscope where you can flow blood cells or other cells through and visualize them in 3-D.” He also envisions screens, layered with microlenses, that are designed to refract light into specific directions. “Can we project information to one part of a crowd and different information to another part of crowd in a stadium?” Kolle says. “These kinds of optics are challenging, but possible.” This research was supported, in part, by the National Science Foundation, the Natural Sciences and Engineering Research Council of Canada, and the Max Planck Society.
News Article | February 21, 2017
Scientists from the Broad Institute of MIT and Harvard in Cambridge, Massachusetts, have identified novel mutations in bacteria that promote the evolution of high-level antibiotic resistance. The findings, published in eLife, add to our understanding of how antibiotic resistance develops, which the team says is crucial for maintaining the effectiveness of both existing and future drugs. The rise of antibiotic-resistant bacteria is challenging clinicians, with some infections already resistant to nearly all available drugs. A 2013 report from the Centers for Disease Control and Prevention estimates that such infections kill at least 23,000 people each year in the United States alone*. Deborah Hung, senior author of the current study and Core Institute Member and Co-Director of the Infectious Disease and Microbiome Program at the Broad Institute, says: "Some species of bacteria, including mycobacteria, develop drug resistance as a result of mutations in their genes. We wanted to gain new insight into the molecular processes that promote resistance in these species by looking at the relationships between the concentration of antibiotics, their killing effects on bacteria, and the emergence of drug-resistant mutants." To do this, Hung and her team grew hundreds of cultures of the species Mycobacterium smegmatis (M. smegmatis), a cousin of the bacterium that causes tuberculosis. They exposed the bacteria to low antibiotic concentrations, where the drugs' microbe-killing effects were relatively slow. This allowed the team to monitor the killing of sensitive bacteria while isolating individual wells where mutants developed. "We detected the outgrowth of drug-resistant mutants in a fraction of our cultures," says first author James Gomez. "Each individual carried single mutations in different components of the ribosome, the complex molecular machine responsible for building proteins within cells." The team found that these novel ribosomal mutations granted the bacteria resistance to several different classes of antibiotics that do not even target the ribosome, and to which the mutants had never been exposed. They also enhanced resistance to two non-antibiotic stresses: heat shock and membrane stress. Gomez explains: "We did see a fitness cost to the bacteria in that the mutations reduced their growth rate. However, the reprogramming that occurred within the cells in response to the mutations made the bacteria much less sensitive to both antibiotic and non-antibiotic stresses. This suggests that, in species such as M. smegmatis, these types of mutations can enhance fitness in multidrug environments and serve as stepping stones toward the development of high-level drug resistance, despite the cost that the mutations have on growth." The team now wants to explore this phenomenon across diverse bacterial species, including Mycobacterium tuberculosis, by coupling experimental biological approaches with a thorough exploration of genome sequence information. A more complete understanding of how multidrug resistance emerges could help in the development or optimisation of new drugs for treating bacterial infections. The paper 'Ribosomal mutations promote the evolution of antibiotic resistance in a multidrug environment' can be freely accessed online at http://dx. . Contents, including text, figures, and data, are free to reuse under a CC BY 4.0 license. *CDC. Antibiotic Resistance Threats in the United States, 2013. Centers for Disease Control and Prevention, 2013: https:/ eLife is a unique collaboration between the funders and practitioners of research to improve the way important research is selected, presented, and shared. eLife publishes outstanding works across the life sciences and biomedicine -- from basic biological research to applied, translational, and clinical studies. All papers are selected by active scientists in the research community. Decisions and responses are agreed by the reviewers and consolidated by the Reviewing Editor into a single, clear set of instructions for authors, removing the need for laborious cycles of revision and allowing authors to publish their findings quickly. eLife is supported by the Howard Hughes Medical Institute, the Max Planck Society, and the Wellcome Trust. Learn more at elifesciences.org.
News Article | February 21, 2017
Some organisms might have an interesting strategy for long-term survival: switching between two unsustainable forms of behaviour that, when kept unchecked, can actually cause them to wipe out their own homes. This discovery, published in the journal eLife, could provide insight into how some species, including humans, can survive and even thrive in harsh conditions and with limited environmental resources. During their life cycles, organisms such as slime moulds switch between living as single, free-ranging individuals (known as 'nomads') and living communally in a colony. To explore the benefits of this adaptation, researchers from the Singapore Institute of Technology and Yale University created a mathematical model that can be applied to such behaviour-switching organisms. Their model suggests that the strategy can ensure survival, even when each behavior would independently result in extinction. "This is an example of a counter-intuitive phenomenon called Parrondo's paradox, where two losing games, when played in a specific order, can surprisingly end in a victory," says first author Zong Xuan Tan, an undergraduate at Yale University. "Previous studies have demonstrated that the paradox can occur when organisms are faced with unpredictable environments. However, our research shows that externally caused environmental variation is not actually needed for organisms to display this behaviour - the paradox can also occur when they form colonies that destroy their own habitats." The model considers a situation where nomads live relatively independently and are unaffected by competition and cooperation, but are subject to steady extinction under poor environmental conditions. Colonists, on the other hand, live in close proximity and are subject to both competitive and cooperative effects. They can also deplete the resources of their habitat over time, resulting in their own extinction. "These two losing strategies can actually lead to survival because when the organisms switch from their destructive colonial form to live as nomads instead, this allows for habitat regeneration," says senior author Kang Hao Cheong, Assistant Professor in the Engineering Cluster at the Singapore Institute of Technology. "Once colonial population sizes are sufficiently small, environmental resources are allowed to recover. The nomads can then take advantage of the restored stocks by switching back to colonialism." Cheong explains that a variety of mechanisms might trigger this switching behaviour. For example, highly mobile nomadic organisms could frequently re-enter their original colonial habitat, thereby detecting whether resource levels are high enough for recolonization. Switching behaviour could also be genetically programmed, such that 'involuntary' individual sacrifice ends up promoting the long-term survival of the species. "The possibility of an ecological Parrondo's paradox could have wide-ranging applications across the fields of ecology and population biology," Cheong says. Tan and Cheong are already exploring ways to adapt their model to specific organisms, and to investigate the possible evolutionary origins of this behavioural phenomenon. The paper 'Nomadic-colonial life strategies enable paradoxical survival and growth despite habitat destruction' can be freely accessed online at http://dx. . Contents, including text, figures, and data, are free to reuse under a CC BY 4.0 license. eLife is a unique collaboration between the funders and practitioners of research to improve the way important research is selected, presented, and shared. eLife publishes outstanding works across the life sciences and biomedicine -- from basic biological research to applied, translational, and clinical studies. All papers are selected by active scientists in the research community. Decisions and responses are agreed by the reviewers and consolidated by the Reviewing Editor into a single, clear set of instructions for authors, removing the need for laborious cycles of revision and allowing authors to publish their findings quickly. eLife is supported by the Howard Hughes Medical Institute, the Max Planck Society, and the Wellcome Trust. Learn more at elifesciences.org.
News Article | March 1, 2017
Glass artisans in medieval times exploited the effect long before it was even known. They coloured the magnificent windows of gothic cathedrals with nanoparticles of gold, which glowed red in the light. It was not until the middle of the 20th century that the underlying physical phenomenon was given a name: plasmons. These collective oscillations of free electrons are stimulated by the absorption of incident electromagnetic radiation. The smaller the metallic particles, the shorter the wavelength of the absorbed radiation. In some cases, the resonance frequency, i.e., the absorption maximum, falls within the visible light spectrum. The unabsorbed part of the spectrum is then scattered or reflected, creating an impression of colour. The metallic particles, which usually appear silvery, copper-coloured or golden, then take on entirely new colours. Researchers are also taking advantage of the effect to develop plasmonic printing, in which tailor-made square metal particles are arranged in specific patterns on a substrate. The edge length of the particles is in the order of less than 100 nanometres (100 billionths of a metre). This allows a resolution of 100,000 dots per inch – several times greater than what today's printers and displays can achieve. For metallic particles measuring several 100 nanometres across, the resonance frequency of the plasmons lies within the visible light spectrum. When white light falls on such particles, they appear in a specific colour, for example red or blue. The colour of the metal in question is determined by the size of the particles and their distance from each other. These adjustment parameters therefore serve the same purpose in plasmonic printing as the palette of colours in painting. The trick with the chemical reaction The Smart Nanoplasmonics Research Group at the Max Planck Institute for Intelligent Systems in Stuttgart also makes use of this colour variability. They are currently working on making dynamic plasmonic printing. They have now presented an approach that allows them to alter the colours of the pixels predictably – even after an image has been printed. "The trick is to use magnesium. It can undergo a reversible chemical reaction in which the metallic character of the element is lost," explains Laura Na Liu, who leads the Stuttgart research group. "Magnesium can absorb up to 7.6% of hydrogen by weight to form magnesium hydride, or MgH2", Liu continues. The researchers coat the magnesium with palladium, which acts as a catalyst in the reaction. During the continuous transition of metallic magnesium into non-metallic MgH2, the colour of some of the pixels changes several times. The colour change and the speed of the rate at which it proceeds follow a clear pattern. This is determined both by the size of and the distance between the individual magnesium particles as well as by the amount of hydrogen present. In the case of total hydrogen saturation, the colour disappears completely, and the pixels reflect all the white light that falls on them. This is because the magnesium is no longer present in metallic form but only as MgH2. Hence, there are also no free metal electrons that can be made to oscillate. The scientists demonstrated the effect of such dynamic colour behaviour on a plasmonic print of Minerva, the Roman goddess of wisdom, which also bore the logo of the Max Planck Society. They chose the size of their magnesium particles so that Minerva's hair first appeared reddish, the head covering yellow, the feather crest red and the laurel wreath and outline of her face blue. They then washed the micro-print with hydrogen. A time-lapse film shows how the individual colours change. Yellow turns red, red turns blue, and blue turns white. After a few minutes all the colours disappear, revealing a white surface instead of Minerva. The scientists also showed that this process is reversible by replacing the hydrogen stream with a stream of oxygen. The oxygen reacts with the hydrogen in the magnesium hydride to form water, so that the magnesium particles become metallic again. The pixels then change back in reverse order, and in the end Minerva appears in her original colours. In a similar manner the researchers first made the micro image of a famous Van Gogh painting disappear and then reappear. They also produced complex animations that give the impression of fireworks. The principle of a new encryption technique Laura Na Liu can imagine using this principle in a new encryption technology. To demonstrate this, the group formed various letters with magnesium pixels. The addition of hydrogen then caused some letters to disappear over time, like the image of Minerva. "As for the rest of the letters, a thin oxide layer formed on the magnesium particles after exposing the sample in air for a short time before palladium deposition," Liu explains. This layer is impermeable to hydrogen. The magnesium lying under the oxide layer therefore remains metallic − and visible − because light is able to excite the plasmons in the magnesium. In this way it is possible to conceal a message, for example by mixing real and nonsensical information. Only the intended recipient is able to make the nonsensical information disappear and filter out the real message. For example, after decoding the message "Hartford" with hydrogen, only the words "art or" would remain visible. To make it more difficult to crack such encrypted messages, the group is currently working on a process that would require a precisely adjusted hydrogen concentration for deciphering. Liu believes that the technology could also be used some day in the fight against counterfeiting. "For example, plasmonic security features could be printed on banknotes or pharmaceutical packs, which could later be checked or read only under specific conditions unknown to counterfeiters." It doesn't necessarily have to be hydrogen Laura Na Liu knows that the use of hydrogen makes some applications difficult and impractical for everyday use such as in mobile displays. "We see our work as a starting shot for a new principle: the use of chemical reactions for dynamic printing," the Stuttgart physicist says. It is certainly conceivable that the research will soon lead to the discovery of chemical reactions for colour changes other than the phase transition between magnesium and magnesium dihydride, for example, reactions that require no gaseous reactants. Explore further: Rotate an image, another one appears (w/ Video)