Volume 514 Number 7522


Dust to dust p.273

What lessons can be learned from the presentation of the gravitational-waves story?

doi: 10.1038/514273b

Review rewards p.274

Welcome efforts are being made to recognize academics who give up their time to peer review.

doi: 10.1038/514274a


Ebola by the numbers p.284

As the virus continues to rampage in West Africa, Nature’s graphic offers a guide to the figures that matter.

doi: 10.1038/514284a

News Features

The university experiment p.287

Universities must evolve if they are to survive. A special issue of Nature examines the many ways to build a modern campus.

doi: 10.1038/514287a

Campus as laboratory p.288

Innovative ways of teaching, learning and doing research are helping universities around the globe to adapt to the modern world.

doi: 10.1038/514288a

The research rethink p.292

Arizona State University is trying to reinvent academia by tearing down walls between disciplines.

doi: 10.1038/514292a

News & Views

Survival of the fittest group p.308

Experiments with social spiders find that colony size and composition affect colony survival in a site-specific manner, indicating that natural selection on group-level traits contributes to local adaptation. See Letter p.359

doi: 10.1038/nature13755

Staying together on the road to metastasis p.309

Most deaths from breast cancer occur when the primary tumour spreads to secondary sites. It now emerges that clusters of tumour cells that enter the bloodstream form metastases more often than single circulating tumour cells.

doi: 10.1038/514309a

How tiny galaxies form stars p.310

Observations of two faint galaxies with a low abundance of elements heavier than helium show that the galaxies have an efficiency of star formation less than one-tenth of that of the Milky Way and similar galaxies. See Letter p.335

doi: 10.1038/514310a

The origin of human retinoblastoma p.312

The cellular origins of most human cancers remain unknown, but an analysis of embryonic retinal cells identifies differentiating cones as the cell of origin for the childhood cancer retinoblastoma. See Letter p.385

doi: 10.1038/nature13748

A historic experiment redesigned p.313

Large quasiparticles known as Rydberg excitons have been detected in a natural crystal of copper oxide. The result may find use in applications such as single-photon logic devices. See Letter p.343

doi: 10.1038/514313a

Of monarchs and migration p.314

The genomes of 101 monarch butterflies from migratory and resident populations have been sequenced, revealing genes and molecular pathways that underlie insect migration and colouration. See Article p.317

doi: 10.1038/nature13757


The genetics of monarch butterfly migration and warning colouration p.317

The monarch butterfly, well known for its spectacular annual migration across North America, is shown by genome sequencing of monarchs from around the world to have been ancestrally migratory and to have dispersed out of North America to occupy its current broad distribution; the authors also discovered signatures of selection associated with migration within loci implicated in flight muscle function, leading to greater flight efficiency.

doi: 10.1038/nature13812

Clonal dynamics of native haematopoiesis p.322

On the basis of transplantation experiments it is generally believed that a very small number of haematopoietic stem cells maintain multi-lineage haematopoiesis by stably producing a hierarchy of short-lived progenitor cells; here a new transposon-based labelling technique shows that this might not be the case during non-transplant haematopoiesis, but rather that a large number of long-lived progenitors are the main drivers of steady-state haematopoiesis during most of adulthood.

doi: 10.1038/nature13824


Inefficient star formation in extremely metal poor galaxies p.335

Spatially resolved infrared observations of two galaxies with oxygen abundances below 10 per cent of the solar value show that stars formed very inefficiently in seven star-forming clumps, suggesting that star formation may have been very inefficient in the early Universe.

doi: 10.1038/nature13820

Binary orbits as the driver of γ-ray emission and mass ejection in classical novae p.339

Classical novae are the most common astrophysical thermonuclear explosions, occurring on the surfaces of white dwarf stars accreting gas from companions in binary star systems. Novae typically expel about 10−4 solar masses of material at velocities exceeding 1,000 kilometres per second. However, the mechanism of mass ejection in novae is poorly understood, and could be dominated by the impulsive flash of thermonuclear energy, prolonged optically thick winds or binary interaction with the nova envelope. Classical novae are now routinely detected at gigaelectronvolt γ-ray wavelengths, suggesting that relativistic particles are accelerated by strong shocks in the ejecta. Here we report high-resolution radio imaging of the γ-ray-emitting nova V959 Mon. We find that its ejecta were shaped by the motion of the binary system: some gas was expelled rapidly along the poles as a wind from the white dwarf, while denser material drifted out along the equatorial plane, propelled by orbital motion. At the interface between the equatorial and polar regions, we observe synchrotron emission indicative of shocks and relativistic particle acceleration, thereby pinpointing the location of γ-ray production. Binary shaping of the nova ejecta and associated internal shocks are expected to be widespread among novae, explaining why many novae are γ-ray emitters.

doi: 10.1038/nature13773

Giant Rydberg excitons in the copper oxide Cu2O p.343

Rydberg excitons (condensed-matter analogues of hydrogen atoms) are shown to exist in single-crystal copper oxide with principal quantum numbers as large as n = 25 and giant wavefunctions with extensions of around two micrometres; this has implications for research in condensed-matter optics.

doi: 10.1038/nature13832

Lithium–antimony–lead liquid metal battery for grid-level energy storage p.348

All-liquid batteries comprising a lithium negative electrode and an antimony–lead positive electrode have a higher current density and a longer cycle life than conventional batteries, can be more easily used to make large-scale storage systems, and so potentially present a low-cost means of grid-level energy storage.

doi: 10.1038/nature13700

Site-specific group selection drives locally adapted group compositions p.359

Here, colonies of social spiders are used to investigate the evolution of a group-level trait, the ratio of individuals with the ‘docile’ versus ‘aggressive’ phenotype in a colony; experimental colonies were generated with varying ratios and established in the wild, revealing group-level selection.

doi: 10.1038/nature13811

Hallucigenia’s onychophoran-like claws and the case for Tactopoda p.363

The claws of the Cambrian lobopodian Hallucigenia resemble the claws and jaws of extant onychophorans, establishing a close relationship between hallucigeniid lobopodians and onychophorans, resolving tardigrades as the closest extant relatives of true arthropods, and showing that the earliest ancestor of the arthropods and their kin would have looked like a lobopodian.

doi: 10.1038/nature13576

OSCA1 mediates osmotic-stress-evoked Ca2+ increases vital for osmosensing in Arabidopsis p.367

Water is crucial to plant growth and development. Environmental water deficiency triggers an osmotic stress signalling cascade, which induces short-term cellular responses to reduce water loss and long-term responses to remodel the transcriptional network and physiological and developmental processes. Several signalling components that have been identified by extensive genetic screens for altered sensitivities to osmotic stress seem to function downstream of the perception of osmotic stress. It is known that hyperosmolality and various other stimuli trigger increases in cytosolic free calcium concentration ([Ca2+]i). Considering that in bacteria and animals osmosensing Ca2+ channels serve as osmosensors, hyperosmolality-induced [Ca2+]i increases have been widely speculated to be involved in osmosensing in plants. However, the molecular nature of corresponding Ca2+ channels remain unclear. Here we describe a hyperosmolality-gated calcium-permeable channel and its function in osmosensing in plants. Using calcium-imaging-based unbiased forward genetic screens we isolated Arabidopsis mutants that exhibit low hyperosmolality-induced [Ca2+]i increases. These mutants were rescreened for their cellular, physiological and developmental responses to osmotic stress, and those with clear combined phenotypes were selected for further physical mapping. One of the mutants, reduced hyperosmolality-induced [Ca2+]i increase 1 (osca1), displays impaired osmotic Ca2+ signalling in guard cells and root cells, and attenuated water transpiration regulation and root growth in response to osmotic stress. OSCA1 is identified as a previously unknown plasma membrane protein and forms hyperosmolality-gated calcium-permeable channels, revealing that OSCA1 may be an osmosensor. OSCA1 represents a channel responsible for [Ca2+]i increases induced by a stimulus in plants, opening up new avenues for studying Ca2+ machineries for other stimuli and providing potential molecular genetic targets for engineering drought-resistant crops.

doi: 10.1038/nature13593

Antiviral immunity via RIG-I-mediated recognition of RNA bearing 5′-diphosphates p.372

Mammalian cells possess mechanisms to detect and defend themselves from invading viruses. In the cytosol, the RIG-I-like receptors (RLRs), RIG-I (retinoic acid-inducible gene I; encoded by DDX58) and MDA5 (melanoma differentiation-associated gene 5; encoded by IFIH1) sense atypical RNAs associated with virus infection. Detection triggers a signalling cascade via the adaptor MAVS that culminates in the production of type I interferons (IFN-α and β; hereafter IFN), which are key antiviral cytokines. RIG-I and MDA5 are activated by distinct viral RNA structures and much evidence indicates that RIG-I responds to RNAs bearing a triphosphate (ppp) moiety in conjunction with a blunt-ended, base-paired region at the 5′-end (reviewed in refs 1, 2, 3). Here we show that RIG-I also mediates antiviral responses to RNAs bearing 5′-diphosphates (5′pp). Genomes from mammalian reoviruses with 5′pp termini, 5′pp-RNA isolated from yeast L-A virus, and base-paired 5′pp-RNAs made by in vitro transcription or chemical synthesis, all bind to RIG-I and serve as RIG-I agonists. Furthermore, a RIG-I-dependent response to 5′pp-RNA is essential for controlling reovirus infection in cultured cells and in mice. Thus, the minimal determinant for RIG-I recognition is a base-paired RNA with 5′pp. Such RNAs are found in some viruses but not in uninfected cells, indicating that recognition of 5′pp-RNA, like that of 5′ppp-RNA, acts as a powerful means of self/non-self discrimination by the innate immune system.

doi: 10.1038/nature13590

CRISPR-mediated direct mutation of cancer genes in the mouse liver p.380

CRISPR plasmids targeting Pten and p53, alone and in combination, are delivered by hydrodynamic injection to the liver; the CRISPR-mediated mutations phenocopy the effects of deletions using Cre–LoxP technology, allowing the direct mutation of tumour suppressor genes and oncogenes in the liver using the CRISPR/Cas system, which presents a new approach for rapid development of liver cancer models and functional genomics.

doi: 10.1038/nature13589

Rb suppresses human cone-precursor-derived retinoblastoma tumours p.385

The nature of the retinal cell-type-specific circuitry that predisposes to retinoblastoma is demonstrated, in which a program that is unique to post-mitotic human cone precursors sensitizes to the oncogenic effects of retinoblastoma (Rb) protein depletion; hence, the loss of Rb collaborates with the molecular framework of cone precursors to initiate tumorigenesis.

doi: 10.1038/nature13813