Nature is the international weekly journal of science: a magazine style journal that publishes full-length research papers in all disciplines of science, as well as News and Views, reviews, news, features, commentaries, web focuses and more, covering all branches of science and how science impacts upon all aspects of society and life.
Explosions of plasma in the Sun's atmosphere can reach temperatures of nearly 100,000 °C, much hotter than scientists had expected.The finding is one of several about the region between the solar surface and the uppermost edge of the Sun's atmosphere, or corona, revealed by
Disrupted sleep patterns alter the composition of gut bacteria, leading to metabolic problems.Eran Elinav at the Weizmann Institute of Science in Rehovot, Israel, and his team found that the abundance of gut microbes in mice fluctuates daily in sync with host feeding times. But
Wild southern white rhinoceroses could go extinct in just nine years because of poaching, but could be saved if trade in their horns were to be carefully managed.Poachers killed almost 1,000 southern white rhinoceroses (Ceratotherium simum simum; pictured) for their horns
Implanted retinal cells derived from stem cells seem to be improving vision in some people in two early-stage clinical trials.Steven Schwartz at the University of California, Los Angeles, Robert Lanza at Advanced Cell Technology in Marlborough, Massachusetts, and their team grew retinal pigmented epithelial
A laser beam can move matter tens of centimetres and in two directions.Such tractor beams have been used to shift small objects very short distances. To scale this up, Wieslaw Krolikowski at the Australian National University in Canberra and his team fired a laser
Tornadoes in the United States have been happening on fewer days since the 1970s, but more tornadoes have touched down (pictured) on those days.The overall number of US tornadoes has not changed in recent decades. However, in analysing the national tornado database,
Blocking a brain-cell receptor boosts the brain's ability to form new neuronal connections as it adapts to changing stimuli.Carla Shatz at Stanford University in California and her colleagues disrupted the receptor, PirB, in the visual centre of mouse brains by either genetically deleting it
Bizarre 500-million-year-old sea creatures called vetulicolians are relatives of vertebrates.Palaeontologists have struggled to identify the relationship between living animals and these extinct organisms, because of their odd combination of features such as gill slits and a segmented abdomen. A team led by Diego García-Bellido
Engineering certain immune cells to kill cancerous cells in leukaemia has driven the disease into remission for up to two years in more than half of participants in an early-stage clinical trial.Stephan Grupp at the Children's Hospital of Philadelphia, Pennsylvania, and his co-workers tested
Amid increased competition for faculty jobs in biomedicine, some have suggested cutting the number of PhD students. So when a senior scientist advised against this, the online world took notice. Eve Marder, a neuroscientist at Brandeis University in Waltham, Massachusetts, argued in the journal eLife
In 2004, researchers announced the discovery of Homo floresiensis, a small relative of modern humans that lived as recently as 18,000 years ago. The ‘hobbit’ is now considered the most important hominin fossil in a generation. Here, the scientists behind the find tell its story.
David Victor and Charles Kennel challenge the practice of using global mean temperature as the main measure of danger from climate change (Nature514, 30–31;10.1038/514030a2014). On the basis of 40 years of science and policy research, there
David Victor and Charles Kennel argue that aiming to keep average global warming within 2 °C of pre-industrial temperatures is neither politically nor scientifically useful (Nature514, 30–31;10.1038/514030a2014). I disagree: global temperature change is the closest thing
China last month donated to the United Nations the first open-access, high-resolution map of Earth's land cover, as a contribution towards global sustainable development and combating climate change.The map, known as GlobeLand30, comprises data sets collected at 30-metre resolution — more than ten times
Mark Stafford-Smith urges scientists to engage more effectively with the United Nations' Sustainable Development Goals to ensure that their environmental targets are quantifiable (Nature513, 281;10.1038/513281a2014). When stakeholder values are diverse and passionately defended, however, such targets may not
Amaya Moro-Martin asserts that the European Science Foundation (ESF) supported a “flawed evaluation process” for research in Portugal (Nature514, 141;10.1038/514141a2014). This unsubstantiated allegation undermines the foundation's work and is detrimental to the many excellent reviewers and panel members
Arising from E.-Z. Shen et al.Nature508, 128–132 (2014); doi:10.1038/nature13012Ageing and lifespan of organisms are determined by complicated interactions between their genetics and the environment, but the cellular mechanisms remain controversial; several studies suggest that cellular energy metabolism and free radical dynamics affect lifespan, implicating mitochondrial function. Recently, Shen et al. provided apparent mechanistic insight by reporting that mitochondrial oscillations of ‘free radical production’, called ‘mitoflashes’, in the pharynx of three-day old Caenorhabditis elegans correlated inversely with lifespan. The interpretation of mitoflashes as ‘bursts of superoxide radicals’ assumes that circularly permuted yellow fluorescent protein (cpYFP) is a reliable indicator of mitochondrial superoxide, but this interpretation has been criticized because experiments and theoretical considerations both show that changes in cpYFP fluorescence are due to alterations in pH, not superoxide. Here we show that purified cpYFP is completely unresponsive to superoxide, and that mitoflashes do not reflect superoxide generation or provide a link between mitochondrial free radical dynamics and lifespan. There is a Reply to this Brief Communication Arising by Cheng, H. et al.Nature514,http://dx.doi.org/10.1038/nature13859 (2014).
Replying to M. Schwarzländer et al.Nature514, http://dx.doi.org/10.1038/nature13858 (2014)In the accompanying Comment, Schwarzländer et al. challenged our recent study because they failed to reproduce our previous finding that the fluorescence intensity of purified circularly permuted yellow fluorescent protein (cpYFP) increases in response to oxygen and superoxide anions produced by xanthine (X) plus xanthine oxidase (XO). Starting from a ‘fully reduced’ state (incubation with 10 mM dithiothreitol for >3 h) and in the presence of 75 mM HEPES, we demonstrated that cpYFP exhibits a twofold fluorescence increase after oxygenation, and an additional twofold increase after the subsequent addition of X plus XO, which could not be accounted for by solvent (potassium hydroxide)-induced alkalization. Furthermore, the xanthine plus xanthine oxidase-induced increase in cpYFP fluorescence was reversed by Cu/Zn superoxide dismutase (600 U ml−1). We also found that the fluorescence intensity of fully reduced cpYFP increased >fourfold after incubation with 1 mM aldrithiol. Notably, recombinant cpYFP purified in the absence of dithiothreitol treatment exhibits a high fluorescence comparable to that of the fully oxidized state, indicating the high susceptibility of cpYFP to oxidation in non-reducing environments. Therefore, ensuring a fully reduced state of cpYFP is essential for the probe to sense superoxide in vitro. This property is probably the reason that the probe functions readily as a reversible superoxide biosensor when targeted to the reduced environment of the mitochondrial matrix. Unfortunately, from the brief description of the methods and limited data provided by Schwarzländer et al., it is not possible to determine whether cpYFP was fully reduced in their experiments, or whether sufficient precautions were taken to prevent oxidation of the probe. Moreover, in our experiments cpYFP was expressed in Escherichia coli BL21(DE3)LysS cells, whereas Schwarzländer et al. used E. coli Origami, a trxB (thioredoxin reductase) mutant strain that also lacks glutathione reductase needed to fully limit cysteine oxidation, which could result in an increased oxidative status of their purified cpYFP rendering it non-responsive to superoxide.
Arising from L. Romani et al.Nature451,211–215 (2008); doi:10.1038/nature06471Chronic granulomatous disease (CGD) is an inherited disorder of phagocyte function, caused by a genetic defect in NADPH oxidase (NOX2), leading to an impaired ability of leukocytes to produce superoxide (); CGD subjects are susceptible to chronic infections and hyper-inflammation, although the mechanisms remain unclear. Romani et al. reported an aberrant inflammatory response to pulmonary aspergillosis as well as sterile Aspergillusfumigatus to be mediated by a defective tryptophan catabolism to kynurenine caused by lack of in CGD mice. Kynurenine is formed by indoleamine 2,3-dioxygenase-1 (IDO1) in a reaction originally reported to depend on (ref. 3). Here we show that NOX2 deficiency does not attenuate IDO1-mediated tryptophan catabolism in human phagocytes and CGD mice with granulomas arising from an inflammatory response to Aspergillus. There is a Reply to this Brief Communications Arising by Romani, L. & Puccetti, P. Nature514,http://dx.doi.org/10.1038/nature13845 (2014).
Replying to G. J. Maghzal et al. Nature514,http://dx.doi.org/10.1038/nature13844 (2014)After our initial observation of defective tryptophan catabolism in experimental chronic granulomatous disease (CGD), several laboratories have been testing the indoleamine 2,3-dioxygenase (IDO1) competence of cells from CGD patients. In most instances, they found no impairment in IDO1 competence in terms of tryptophan catabolic activity in vitro by polymorphonuclear leukocytes and monocyte-derived dendritic cells, leading to the conclusion that there is no obvious defect in the production of kynurenine (the first by-product of tryptophan degradation)—hence in the IDO1-dependent mechanism of tolerogenesis as a whole in human CGD. In the accompanying Comment, Maghzal et al. report that tryptophan catabolism is unaffected in chronic granulomatous disease, again by measurements of kynurenine production.
A high-resolution crystal structure of the HIV-1 Env trimer proteins, in their form before they fuse with target cells, will aid the design of vaccines that elicit protective immune responses to this protein complex. See Article p.455
Transplanting gene-corrected macrophage cells directly into the lungs of mice has been shown to effectively treat their pulmonary alveolar proteinosis, a hereditary lung disease also found in humans. See Article p.450
An analysis of hundreds of star-grazing comets in a young planetary system shows that they form two families: a group of old, dried-out comets and a younger group probably related to the break-up of a larger planetary body. See Letter p.462
During inflammation, lymph nodes swell with an influx of immune cells. New findings identify a signalling pathway that induces relaxation in the contractile cells that give structure to these organs. See Letter p.498
In a finding that highlights ways to optimize the efficacy of antibody-based therapeutics and vaccines, the activity of potent HIV-1-neutralizing antibodies has been confirmed to depend on cellular binding to the antibodies' Fc regions.
We present the high-quality genome sequence of a ∼45,000-year-old modern human male from Siberia. This individual derives from a population that lived before—or simultaneously with—the separation of the populations in western and eastern Eurasia and carries a similar amount of Neanderthal ancestry as present-day Eurasians.
Bone-marrow transplantation is an effective cell therapy but requires myeloablation, which increases infection risk and mortality. Recent lineage-tracing studies documenting that resident macrophage populations self-maintain independently of haematological progenitors prompted us to consider organ-targeted, cell-specific therapy. Here, using granulocyte–macrophage colony-stimulating factor (GM-CSF) receptor-β-deficient (Csf2rb
The human immunodeficiency virus type 1 (HIV-1) envelope (Env) spike, comprising three gp120 and three gp41 subunits, is a conformational machine that facilitates HIV-1 entry by rearranging from a mature unliganded state, through receptor-bound intermediates, to a post-fusion state. As the sole viral antigen on
The young planetary system surrounding the star β Pictoris harbours active minor bodies. These asteroids and comets produce a large amount of dust and gas through collisions and evaporation, as happened early in the history of our Solar System. Spectroscopic observations of β Pictoris reveal a high rate of transits of small evaporating bodies, that is, exocomets. Here we report an analysis of more than 1,000 archival spectra gathered between 2003 and 2011, which provides a sample of about 6,000 variable absorption signatures arising from exocomets transiting the disk of the parent star. Statistical analysis of the observed properties of these exocomets allows us to identify two populations with different physical properties. One family consists of exocomets producing shallow absorption lines, which can be attributed to old exhausted (that is, strongly depleted in volatiles) comets trapped in a mean motion resonance with a massive planet. Another family consists of exocomets producing deep absorption lines, which may be related to the recent fragmentation of one or a few parent bodies. Our results show that the evaporating bodies observed for decades in the β Pictoris system are analogous to the comets in our own Solar System.
The physical mechanism responsible for coronal mass ejections has been uncertain for many years, in large part because of the difficulty of knowing the three-dimensional magnetic field in the low corona. Two possible models have emerged. In the first, a twisted flux rope moves out of equilibrium or becomes unstable, and the subsequent reconnection then powers the ejection. In the second, a new flux rope forms as a result of the reconnection of the magnetic lines of an arcade (a group of arches of field lines) during the eruption itself. Observational support for both mechanisms has been claimed. Here we report modelling which demonstrates that twisted flux ropes lead to the ejection, in support of the first model. After seeing a coronal mass ejection, we use the observed photospheric magnetic field in that region from four days earlier as a boundary condition to determine the magnetic field configuration. The field evolves slowly before the eruption, such that it can be treated effectively as a static solution. We find that on the fourth day a flux rope forms and grows (increasing its free energy). This solution then becomes the initial condition as we let the model evolve dynamically under conditions driven by photospheric changes (such as flux cancellation). When the magnetic energy stored in the configuration is too high, no equilibrium is possible and the flux rope is ‘squeezed’ upwards. The subsequent reconnection drives a mass ejection.
The piezoelectric characteristics of nanowires, thin films and bulk crystals have been closely studied for potential applications in sensors, transducers, energy conversion and electronics. With their high crystallinity and ability to withstand enormous strain, two-dimensional materials are of great interest as high-performance piezoelectric materials. Monolayer MoS2 is predicted to be strongly piezoelectric, an effect that disappears in the bulk owing to the opposite orientations of adjacent atomic layers. Here we report the first experimental study of the piezoelectric properties of two-dimensional MoS2 and show that cyclic stretching and releasing of thin MoS2 flakes with an odd number of atomic layers produces oscillating piezoelectric voltage and current outputs, whereas no output is observed for flakes with an even number of layers. A single monolayer flake strained by 0.53% generates a peak output of 15 mV and 20 pA, corresponding to a power density of 2 mW m−2 and a 5.08% mechanical-to-electrical energy conversion efficiency. In agreement with theoretical predictions, the output increases with decreasing thickness and reverses sign when the strain direction is rotated by 90°. Transport measurements show a strong piezotronic effect in single-layer MoS2, but not in bilayer and bulk MoS2. The coupling between piezoelectricity and semiconducting properties in two-dimensional nanomaterials may enable the development of applications in powering nanodevices, adaptive bioprobes and tunable/stretchable electronics/optoelectronics.
One of the most important classifications in chemistry and within the periodic table is the concept of formal oxidation states. The preparation and characterization of compounds containing elements with unusual oxidation states is of great interest to chemists. The highest experimentally known formal oxidation state of any chemical element is at present VIII, although higher oxidation states have been postulated. Compounds with oxidation state VIII include several xenon compounds (for example XeO4 and XeO3F2) and the well-characterized species RuO4 and OsO4 (refs 2, 3, 4). Iridium, which has nine valence electrons, is predicted to have the greatest chance of being oxidized beyond the VIII oxidation state. In recent matrix-isolation experiments, the IrO4 molecule was characterized as an isolated molecule in rare-gas matrices. The valence electron configuration of iridium in IrO4 is 5d1, with a formal oxidation state of VIII. Removal of the remaining d electron from IrO4 would lead to the iridium tetroxide cation ([IrO4]+), which was recently predicted to be stable and in which iridium is in a formal oxidation state of IX. There has been some speculation about the formation of [IrO4]+ species, but these experimental observations have not been structurally confirmed. Here we report the formation of [IrO4]+ and its identification by infrared photodissociation spectroscopy. Quantum-chemical calculations were carried out at the highest level of theory that is available today, and predict that the iridium tetroxide cation, with a Td-symmetrical structure and a d0 electron configuration, is the most stable of all possible [IrO4]+ isomers.