Science

The best in science news, commentary, and research
  • [Editorial] Rethinking graduate education
    [Jul 2015]

    All available evidence suggests that over 60% of new Ph.D.s in science in the United States will not have careers in academic research, yet graduate training in science has followed the same basic format for almost 100 years, heavily focused on producing academic researchers. Given that so many students will not join that community, the system is failing to meet the needs of the majority of its students. Many academic, governmental, and professional leaders and organizations have lamented this disconnect and have suggested worthwhile adjustments, but most of these have been minor changes in graduate course offerings. It is time for the scientific and education communities to take a more fundamental look at how graduate education in science is structured and consider, given the current environment, whether a major reconfiguration of the entire system is needed. Author: Alan I. Leshner
    Categories: Journal Articles
  • [In Brief] This week's section
    [Jul 2015]

    In science news around the world, Chile and the Canary Islands are selected to share the world's largest and most powerful gamma-ray observatory, the new Joep Lange Institute opens in Amsterdam this year to honor the HIV researcher killed in last year's attack on a Malaysia Airlines flight, Nigeria hits an important milestone with its last known case of wild polio occurring a year ago, the five nations ringing the Arctic Ocean sign a declaration to prevent unregulated commercial fishing in its waters, and more. Also, scientists hope to limit damage done to vegetable crops by releasing genetically altered diamondback moths.
    Categories: Journal Articles
  • [In Depth] Scientists ponder an improbably active Pluto
    [Jul 2015]

    On 14 July, NASA's New Horizons spacecraft flew past Pluto, the first reconnaissance of a body in the Kuiper belt, the zone of icy objects beyond the orbit of Neptune. With the flyby complete and the data trickling home, mission scientists focused on a new challenge: making sense of an unexpectedly complex and dynamic world. Pluto contains ice mountains and smooth, crater-free plains—features suggestive of active geological processes. But mission scientists are debating whether these are the result of an atmosphere that shapes the landscape from above, or residual heat in Pluto's interior that could be driving fresh flows of ice onto the surface. Author: Eric Hand
    Categories: Journal Articles
  • [In Depth] New mystery for Native American origins
    [Jul 2015]

    Researchers still argue about how and when the first Americans settled in North and South America, and particularly about whether they came in one or multiple waves. Two new papers, one in Science and the other in Nature, attempt to shed light on this question, but they come to different conclusions: The Science team finds one wave, and the Nature team finds two. The two research groups do agree on one thing, however—some of today's Native Americans have the genes of ancient people from Australia and Melanesia in the southwest Pacific Ocean. Knowing whether that mysterious genetic contribution came early, as the Nature team thinks, or much later, as the Science team concludes, may hold the key to remaining riddles about the peopling of the Americas. Author: Michael Balter
    Categories: Journal Articles
  • [In Depth] Child fights HIV to a draw
    [Jul 2015]

    An 18-year-old woman in France who became infected with HIV as a baby went off antiretroviral drugs 12 years ago and the virus has yet to return to detectable levels on standard blood tests. The woman is not cured, stressed the Pasteur Institute's Asier Sáez-Cirión, who presented details about the case at an international AIDS conference taking place in Vancouver, Canada, this week: His group found HIV DNA in her blood cells and prodded them to make new copies of the virus. Sáez-Cirión has been following a small cohort of other so-called "posttreatment controllers," but the other all became infected with the virus as adults. He noted that the woman, like other posttreatment controllers, was distinct from the 1% of people known as elite controllers who similarly maintain undetectable plasma levels of HIV without treatment. But the elite controllers, in contrast to posttreatment controllers, keep the virus in check from the earliest days of the infection and have an immune response in many cases that explains how they thwart the virus. The hope is that this new case can help clarify how posttreatment controllers keep the virus in check and then use this information to inform both cure and vaccine research. Author: Jon Cohen
    Categories: Journal Articles
  • [In Depth] Iran nuclear deal holds ‘goodies’ for scientists
    [Jul 2015]

    When Iran agreed last week to dismantle large chunks of its nuclear infrastructure, it won more than the promise of relief from crippling economic sanctions. If the agreement survives strong opposition in the U.S. Congress, Iran can expect a rapid expansion of scientific cooperation with Western powers. As its nuclear facilities are repurposed, scientists from Iran and abroad will team up in areas such as nuclear fusion, astrophysics, and radioisotopes for cancer therapy. Some scientific activity will take place at the Fordow uranium enrichment facility, which Iran will convert into an international nuclear, physics, and technology center. Russia will help reconfigure 348 centrifuges there to produce stable isotopes for industry. And Fordow may host a small linear accelerator for basic research in nuclear physics and astrophysics. Iran has agreed to invite proposals for collaborative projects at Fordow and hold an international workshop to review them. Author: Richard Stone
    Categories: Journal Articles
  • [In Depth] Web billionaire bankrolls search for alien signals
    [Jul 2015]

    Are we alone in the universe? Russian internet entrepreneur Yuri Milner wants to know—and he's willing to pay for an answer. Milner has donated $100 million for a 10-year effort to detect signals from other civilizations in the universe, an effort that has drawn high-profile support from physicists and astronomers, including Stephen Hawking. The new project, dubbed "Breakthrough Listen," will boost funding for such searches fivefold and will be 50 times as sensitive as previous efforts and cover 10 times more of the sky. In addition, the project will throw a lifeline to budget-strapped radio telescopes, and it will develop new technology to monitor 10 billion radio frequencies simultaneously. Author: Daniel Clery
    Categories: Journal Articles
  • [Feature] New life for old bones
    [Jul 2015]

    Powered by advances in sequencing technology, the field of ancient DNA has succeeded beyond all expectations, helping researchers to retrieve the entire genomes of Neandertals and other kinds of ancient humans and transforming the picture of human evolution. Researchers have also delved into the genomes of ancient animals—the oldest so far is a 700,000-year-old horse. For years, the methods of extracting and analyzing degraded DNA molecules were so tricky that they remained the exotic province of a few high-profile labs. But now the techniques are spreading. As researchers from many fields realize just how much ancient DNA can tell them, the method is being applied to everything from the peopling of Europe to how plants and pathogens respond to climate change. The explosion of research is transforming the study of the past. Author: Elizabeth Culotta
    Categories: Journal Articles
  • [Feature] Revolution in human evolution
    [Jul 2015]

    New breakthroughs in ancient DNA are causing a revolution in the study of human evolution. By sequencing ancient DNA from the fossils of human ancestors, researchers have recently discovered new types of ancient humans and revealed interbreeding between our ancestors and our archaic cousins, including Neandertals. They are exploring how that genetic legacy is shaping our health and appearance today. And now that investigators can sequence entire ancient populations, ancient DNA is revealing that humans on every continent are a complex mix of archaic and modern DNA. Ancient DNA is enabling researchers to answer questions they could not previously address. As a result, archaeologists, anthropologists, and population geneticists are now seeking collaborations with ancient DNA researchers. Author: Ann Gibbons
    Categories: Journal Articles
  • [Feature] Lost worlds found
    [Jul 2015]

    For decades, scientists have debated why the so-called megafauna disappeared from the Arctic and much of the rest of the world. Now, ancient DNA data have entered the fray. By sequencing whatever DNA emerges (called eDNA) from even a thimbleful of ancient soil, researchers are reconstructing ancient ecosystems as far back as 700,000 years ago with astonishing clarity. In 2011, they documented that a decline in the big herbivores' favorite foods as the ice age thawed coincided with the animals' disappearance. And a paper this week shows that local extinctions were also tied to bursts of warming. Other eDNA data—in this case from lake sediments—are illuminating how the postglacial thaw transformed other landscapes too, such as temperate forests. Finally, eDNA from Antarctic ice cores promises to reveal what happened in the Southern Hemisphere many thousands of years ago. Author: Elizabeth Pennisi
    Categories: Journal Articles
  • [Feature] Prospecting for genetic gold
    [Jul 2015]

    From muddy cliffs in Canada's Yukon territory, where miners flush out gold-laden gravel, Beth Shapiro is netting a different sort of treasure: DNA from thousands of mammoth, bison, horse, and other mammal bones. The goal of this evolutionary biologist from the University of California, Santa Cruz, is to paint a picture of the animal community here during the past 80,000 years. Mining has exposed fossils and layers of volcanic ash, which have been dated with radiometric methods, so Shapiro can pin down the ages of fossils back to before 40,000 years ago, the limit of radiocarbon dating. And thanks to the ever-shrinking cost of sequencing, Shapiro can analyze hundreds of individuals per species to learn about important genetic changes. The project's first papers are expected next year. Author: Elizabeth Pennisi
    Categories: Journal Articles
  • [Feature] Breaking a tropical taboo
    [Jul 2015]

    From muddy cliffs in Canada's Yukon territory, where miners flush out gold-laden gravel, Beth Shapiro is netting a different sort of treasure: DNA from thousands of mammoth, bison, horse, and other mammal bones. The goal of this evolutionary biologist from the University of California, Santa Cruz, is to paint a picture of the animal community here during the past 80,000 years. Mining has exposed fossils and layers of volcanic ash, which have been dated with radiometric methods, so Shapiro can pin down the ages of fossils back to before 40,000 years ago, the limit of radiocarbon dating. And thanks to the ever-shrinking cost of sequencing, Shapiro can analyze hundreds of individuals per species to learn about important genetic changes. The project's first papers are expected next year. Author: Lizzie Wade
    Categories: Journal Articles
  • [Feature] Protein power
    [Jul 2015]

    Ancient DNA may be entering its golden age, but some researchers have their eyes on another molecule that may offer new view of the past: protein, which has some advantages over its more famous cousin. Tissues are full of protein, making analysis easier. Proteins also resist the ravages of time far better than fragile DNA and so have the potential to look further back in time—researchers have identified 300 million year old proteins in fish fossils. Ancient proteins have already illuminated a few far-flung corners of past life, including identifying the family tree of strange, extinct South American mammals that flummoxed even Charles Darwin. The method appears particularly promising in archaeology, where it can reveal the diets and lifestyles of past cultures. Still, the technique has a long way to go before it reaches the maturity of paleogenetics, chiefly because methods to sequence amino acids lag behind DNA sequencing. Author: Robert F. Service
    Categories: Journal Articles
  • [Perspective] Four legs too many?
    [Jul 2015]

    A classic Gary Larson cartoon shows a robed and bearded figure rolling out clay strips, with the caption: “God makes the snake.” Body elongation was certainly fundamental in the evolution of snakes from lizards, as was the shrinking and ultimately the loss of limb pairs (limb reduction). However, informative early fossils are rare, and many details of the transition remain unresolved. A remarkable fossil described on page 416 of this issue by Martill et al. (1) brings fresh perspective to the debate. The aptly named Tetrapodophis combines a snakelike body with fore- and hindlimbs bearing five well-developed digits (see the illustration). Author: Susan Evans
    Categories: Journal Articles
  • [Perspective] Making methane down deep
    [Jul 2015]

    The global ocean is Earth's largest biome, which extends into the sediments and igneous crust below the oceans. The abundance of microbial life beneath the sea floor is at least comparable to that in the oceans (1), but this biome remains poorly understood. The ramifications of a massive buried biosphere are important on a global scale, with sub–sea-floor microbes playing a crucial role in carbon sequestration, element cycles, and Earth's evolution, and likely encompassing staggering metabolic and genetic diversity. On page 420 of this issue, Inagaki et al. (2) report that even at almost 2.5 km beneath the sea floor, microbial life is not only present and compositionally distinct from that in shallower sediments, but also producing methane. Author: Julie A. Huber
    Categories: Journal Articles
  • [Perspective] Moving CTLA-4 from the trash to recycling
    [Jul 2015]

    To prevent immune responses to our own bodies, a series of immune checkpoints exist. Cytotoxic T lymphocyte antigen–4 (CTLA-4) operates the earliest checkpoint controlling whether or not T cells respond to antigen. Manipulation of CTLA-4 has recently gained enormous attention in the field of tumor immunotherapy (1). However, in its day-to-day activities, CTLA-4 prevents autoimmune targeting of tissues (2), though the precise mechanism of action and critical controls influencing CTLA-4 function are still emerging. On page 436 in this issue, Lo et al. (3) provide evidence that an intracellular protein, lipopolysaccharide-responsive and beige-like anchor protein (LRBA) controls CTLA-4 expression and thereby influences immune self-tolerance. Author: David M. Sansom
    Categories: Journal Articles
  • [Perspective] Catalysts by Platonic design
    [Jul 2015]

    Around 360 BCE, in his work Timaeus, the Greek philosopher Plato elaborated on the four elements as the basic components of our cosmos: earth, water, air, and fire. He argued that each element consists of small, highly symmetric corpuscles—the cube for earth, the tetrahedron for fire, the icosahedron for water, and the octahedron for air. The faces of the latter three corpuscles consist of equilateral triangles, which—according to Plato—allows air, water, and fire to interconvert. Plato would likely be thrilled to learn that, as recently confirmed by Huang et al. (1), nanoscale Pt-Ni octahedra are the catalytically most active known material for converting air (molecular oxygen) into water and fire (thermal energy). On page 412 of this issue, Zhang et al. (2) show that octahedral and cubic hollow shells of just a few atomic Pt layers are also versatile catalysts, with the octahedral shells particularly active for oxygen reduction. Such tiny metallic octahedra may one day become the building blocks of electrodes for electrochemical energy conversion. Author: Peter Strasser
    Categories: Journal Articles
  • [Perspective] Breakers and blockers—miRNAs at work
    [Jul 2015]

    MicroRNAs (miRNAs) are small, ~22-nucleotide-long noncoding RNAs. They silence the expression of messenger RNAs (mRNAs) containing complementary sequences (1). The human genome encodes ~1500 miRNAs, each with the potential to bind hundreds of different mRNAs (1). miRNAs regulate many biological processes, and the dysregulation of their expression is linked to various human diseases, including cancer (1). To exert their repressive function, miRNAs associate with the Argonaute family of proteins (AGOs) to form the core of miRNA-induced silencing complexes (miRISCs) (1) (see the figure). In animals, miRISCs silence mRNA expression at two levels, by preventing protein production (translation) and inducing mRNA degradation. Over the past decade, progress has been made in our understanding of the mechanism by which miRISCs induce mRNA degradation, but the question of how miRISCs repress translation remains elusive. Author: Elisa Izaurralde
    Categories: Journal Articles
  • [Perspective] Stretch, wrap, and relax to smartness
    [Jul 2015]

    For thousands of years, humankind has assembled polymeric fibers into textiles for protection against the environment and as an expression of cultural and social status (1). What began with fibers collected from nature (e.g., flax) is now made from a wide range of high-performance polymers that possess useful mechanical, thermal, and chemical properties. Despite these advances, electrically conducting fibers for the most part have remained elusive, with the exception of fibers based on inherently conducting polymers; to date, the electrical properties of conducting fibers deteriorate when repeatedly stretched and released. In a remarkable development, described on page 400 of this issue, Liu et al. (2) have made superelastic conducting fibers based on carbon nanotubes (CNTs) that can be stretched 1000% with almost no change in electrical conductivity, even after thousands of strain cycles. Author: Tushar Ghosh
    Categories: Journal Articles
  • [Policy Forum] Yellow lights for emerging technologies
    [Jul 2015]

    There is an infuriating, often confusing four-way stop intersection near my home. The city refuses to install traffic lights, because devices such as roundabouts, four-way stop signs, and flashing yellow lights, which require drivers to slow and scan before entering, can result in fewer accidents, as well as a faster and more even flow of traffic. There is a lesson to be learned here for regulation of new technologies. Clear, decisive rules are seductive. New drugs cannot be sold untold until proven safe. Food supplements are sold until proven unsafe. Although such clean demarcations can be reassuring, they do not work well for technologies whose applications cannot be presumed safe or unsafe. Author: R. Alta Charo
    Categories: Journal Articles