A tribute to scholars of extraordinary courage.
A politically charged advisory committee meeting may have tipped the scales in favour of a mildly effective female libido drug.
Mental health worsened in the disaster’s aftermath, but survivors also showed resilience.
Unusually warm ocean strengthens calls to consider ecosystem variables in setting catch limits.
Experiment boosts temperature and carbon dioxide to gauge global-warming response.
Amateurs are ready and able to try the CRISPR technique for rewriting genes.
Climate change and the rise of cities have broadened what it means to study ecosystems.
Rising temperatures are threatening urban areas, but efforts to cool them may not work as planned.
Scientists have no shortage of ideas about how to stop tick-borne illnesses. What is holding them back?
News & Views
What happens if some of the particles of a superlattice — an array of identical nanoscale crystals — are replaced with foreign ones? It emerges that the properties of superlattices can be radically altered in this way. See Letter p.450
Two studies reveal that dysfunction in organelles called mitochondria causes the toxic accumulation of mitochondrial proteins in the cell's cytosolic fluid, and identify ways in which damage is mitigated. See Letters p.481 & p.485
Crystal structures of the bacterial protein PglK uncover structural features that suggest how the protein 'flips' lipid-bound oligosaccharide molecules from one side of the cell membrane to the other. See Article p.433
Experiments reveal that positrons — the antimatter equivalents of electrons — can be rapidly accelerated using a plasma wave. The findings pave the way to high-energy electron–positron particle colliders. See Letter p.442
A comparative genomic study shows that, during evolution, nucleus-containing cells acquired DNA from bacteria primarily by endosymbiosis — the uptake and integration of one cell by another. See Article p.427
An atomic laser operating at the shortest wavelength yet achieved has been created by bombarding a copper foil with two X-ray pulses tuned to slightly different energies. The results may lead to ultrastable X-ray lasers. See Letter p.446
Eukaryotes acquired their prokaryotic genes in two episodes of evolutionary influx corresponding to the origin of mitochondria and plastids, respectively, followed by extensive differential gene loss, uncovering a massive imprint of endosymbiosis in the nuclear genomes of complex cells.
In a multiplanet system, when orbital precession is fast enough to resonate with the orbital motion of a distant binary companion, the results range from excitation of large planetary eccentricities and mutual inclinations to total disruption.
A particle accelerator that is two orders of magnitude more efficient than conventional radio-frequency accelerators is described in which positrons (rather than electrons) at the front of a bunch transfer their energy to a substantial number of positrons at the rear of the same bunch by exciting a wakefield in the plasma.
Since the invention of the first lasers in the visible-light region, research has aimed to produce short-wavelength lasers that generate coherent X-rays; the shorter the wavelength, the better the imaging resolution of the laser and the shorter the pulse duration, leading to better temporal resolution in probe measurements. Recently, free-electron lasers based on self-amplified spontaneous emission have made it possible to generate a hard-X-ray laser (that is, the photon energy is of the order of ten kiloelectronvolts) in an ångström-wavelength regime, enabling advances in fields from ultrafast X-ray spectrosopy to X-ray quantum optics. An atomic laser based on neon atoms and pumped by a soft-X-ray (that is, a photon energy of less than one kiloelectronvolt) free-electron laser has been achieved at a wavelength of 14 nanometres. Here, we use a copper target and report a hard-X-ray inner-shell atomic laser operating at a wavelength of 1.5 ångströms. X-ray free-electron laser pulses with an intensity of about 1019 watts per square centimetre tuned to the copper K-absorption edge produced sufficient population inversion to generate strong amplified spontaneous emission on the copper Kα lines. Furthermore, we operated the X-ray free-electron laser source in a two-colour mode, with one colour tuned for pumping and the other for the seed (starting) light for the laser.
Substitutional atomic doping is a process by which atomic defects are introduced into a host material, altering its properties; substitutional doping of cadmium selenide or lead selenide nanocrystal lattices with gold nanocrystals has now been achieved, the key being to ensure that the dopant nanocrystals are similar in size to the host nanocrystals.
A new method for catalysing the cross-coupling of two different aryl electrophiles is described; the principle of this method, which involves cooperation between two metal catalysts that are selective towards different substrates, should be generally useful in catalysis.
Results from mantle flow models reveal a relationship between seismicity away from the plate boundary in the western United States and the rate change of the vertical normal stress from mantle flow, showing that mantle flow plays an important part in shaping topography, tectonics and seismic hazard within such intraplate settings.
A study showing that tunicates possess a proto-placodal ectoderm that produces neurons with dual neurosecretory and chemosensory function, which may represent the ancestral origin of placode-derived neurons in vertebrates.
The mouse retinal ganglion cell type known as the W3B-RGC, which detects motion of objects against a moving background, is shown to receive strong specific and excitatory input from amacrine cells expressing vesicular glutamine transporter 3; this selective connection is mediated by homophilic interactions of the recognition molecule sidekick 2 (Sdk2), which is expressed on both cells, and disruption of this connection affects object motion detection in W3B-RGCs.
Hepatitis C virus cannot replicate in cell culture unless it possesses adaptive mutations; here, expression of cellular factor SEC14L2 is shown to allow replication of diverse hepatitis C virus genotypes in several hepatoma cell lines by enhancing vitamin E-mediated protection against lipid peroxidation.
Live imaging of myc-driven competition in healthy Drosophila tissues shows that cells expressing higher levels of myc actively mix with the neighbouring cells, which increases the probability of eliminating neighbouring cells.
A new pathway of mitochondria-mediated cell death termed mitochondrial precursor over-accumulation stress (mPOS) is identified that could explain the link between mitochondrial dysfunction and misfolding of cytosolic proteins during ageing and disease; the pathway is triggered not only by mutations affecting the core protein import machineries, but also by conditions that interfere with mitochondrial inner membrane integrity and function, and a large network of genes that suppress mPOS in favour of cell survival is also identified.
Mitochondrial dysfunction and cellular protein homeostasis failure are hallmarks of many diseases and age-associated pathologies; this study shows that the mitochondrial import defect of nuclear-encoded proteins triggers a cellular pathway, termed unfolded protein response activated by mistargeting of proteins (UPRam), that acts to minimize the stress caused by non-imported mitochondrial precursor proteins in order to sustain cellular protein homeostasis and organismal fitness.
A study of division in proliferating animal cells points to the existence of a kinetochore-based signalling pathway, independent of furrow formation, centrosomes and microtubules, that couples chromosome segregation to cell division.
All eukaryotes utilize a single termination factor, eRF1, to halt translation when the ribosome encounters one of three possible stop codons; here electron cryo-microscopy structures of ribosome–eRF1 complexes in the process of recognizing each stop codon reveal how stop codons are discriminated from sense codons.
smFRET is used to probe the activation mechanism of two full-length mammalian glutamate receptors, revealing that the extracellular ligand-binding domains of these G-protein-coupled receptors interconvert between three confirmations (resting, activated and a short-lived intermediate state), and that the efficacy of an orthosteric agonist correlates with the degree of occupancy of the active state.