Volume 526 Number 7574


Abstract thoughts p.475

Scientists, meeting organizers and the media must take care with preliminary findings.

doi: 10.1038/526475b

Russian roulette p.475

Attempts to keep foreign interests out of Russian research will only suppress the exchange of information, and risk damaging East–West relations.

doi: 10.1038/526475a

Pick and mix p.476

Food regulators are right to place new forms of data on the safety menu.

doi: 10.1038/526756a


News Features

Hunting the Godzilla El Niño p.490

As a massive El Niño warming builds in the equatorial Pacific Ocean, researchers hope to make the most of their chance to study this havoc-wreaking phenomenon.

doi: 10.1038/526490a

News & Views

Turbulence spreads like wildfire p.508

A simple model captures the key features of the transition from smooth to turbulent flow for a fluid in a pipe. The findings pave the way for more-complex models and may have engineering ramifications. See Letter p.550

doi: 10.1038/526508a

Chronic effects of acute infections p.509

Acute infection of mice with an intestinal pathogen leads to long-lasting inflammation that is maintained by intestinal microorganisms. This observation reveals a path by which infection history can affect long-term immune function.

doi: 10.1038/526509a

Small glacier has big effect on sea-level rise p.510

Models of the West Antarctic Ice Sheet predict substantial ice loss over the next few centuries — and that a glacier expected to contribute greatly to sea-level rise may already be unstable.

doi: 10.1038/526510a

Kidney tissue grown from induced stem cells p.512

Engineered human cells that can give rise to every cell type have been induced to generate structures that resemble an embryonic kidney. This advance charts a course towards growing transplantable kidneys in culture. See Letter p.564

doi: 10.1038/nature15639

Conductive consortia p.513

Physiological analyses, electron microscopy and single-cell chemical imaging suggest that direct electron transfer occurs between the members of methane-oxidizing microbial consortia. See Article p.531 and Letter p.587

doi: 10.1038/526513a

A glimpse of Earth's fate p.515

Analysis of data from the Kepler space observatory and ground-based telescopes has led to the detection of one, and possibly several, minor planets that are in a state of disintegration in orbit around a white dwarf star. See Letter p.546

doi: 10.1038/526515b


Non-coding recurrent mutations in chronic lymphocytic leukaemia p.519

Genomic approaches in more than 500 patients are used to extend the number of chronic lymphocytic leukaemia (CLL) driver alterations, and also identify novel recurrent mutations in non-coding regions, including an enhancer of PAX5 and the 3′ untranslated region of NOTCH1, which lead to aberrant splicing events, increased NOTCH1 protein stability and activity, and an adverse clinical outcome.

doi: 10.1038/nature14666

Mutations driving CLL and their evolution in progression and relapse p.525

This study reports exome sequencing of samples from 538 individuals with chronic lymphocytic leukaemia (CLL), including 278 collected as part of a prospective clinical trial; recurrently mutated genes are identified and pathways involved in CLL are highlighted, as well as their evolution in progression and disease relapse.

doi: 10.1038/nature15395

Single cell activity reveals direct electron transfer in methanotrophic consortia p.531

The anaerobic oxidation of methane in marine sediments is performed by consortia of methane-oxidizing archaea and sulfate-reducing bacteria; an examination of the role of interspecies spatial positioning on single cell activity reveals that interspecies electron transfer may overcome the requirement for close spatial proximity, a proposition supported by large multi-haem cytochromes in ANME-2 genomes as well as redox-active electron microscopy staining.

doi: 10.1038/nature15512


A disintegrating minor planet transiting a white dwarf p.546

The atmospheres of white dwarfs often contain elements heavier than helium, even though these elements would be expected to settle into the stars’ interiors; observations of the white dwarf WD 1145+017 suggest that disintegrating rocky bodies are orbiting the star, perhaps contributing heavy elements to its atmosphere.

doi: 10.1038/nature15527

The rise of fully turbulent flow p.550

Experiments, asymptotic theory and computer simulations of wall-bounded shear flow uncover a bifurcation scenario that explains the transition from localized turbulent patches to fully turbulent flow.

doi: 10.1038/nature15701

Observation of non-Hermitian degeneracies in a chaotic exciton-polariton billiard p.554

Exciton-polaritons are hybrid light–matter quasiparticles formed by strongly interacting photons and excitons (electron–hole pairs) in semiconductor microcavities. They have emerged as a robust solid-state platform for next-generation optoelectronic applications as well as for fundamental studies of quantum many-body physics. Importantly, exciton-polaritons are a profoundly open (that is, non-Hermitian) quantum system, which requires constant pumping of energy and continuously decays, releasing coherent radiation. Thus, the exciton-polaritons always exist in a balanced potential landscape of gain and loss. However, the inherent non-Hermitian nature of this potential has so far been largely ignored in exciton-polariton physics. Here we demonstrate that non-Hermiticity dramatically modifies the structure of modes and spectral degeneracies in exciton-polariton systems, and, therefore, will affect their quantum transport, localization and dynamical properties. Using a spatially structured optical pump, we create a chaotic exciton-polariton billiard—a two-dimensional area enclosed by a curved potential barrier. Eigenmodes of this billiard exhibit multiple non-Hermitian spectral degeneracies, known as exceptional points. Such points can cause remarkable wave phenomena, such as unidirectional transport, anomalous lasing/absorption and chiral modes. By varying parameters of the billiard, we observe crossing and anti-crossing of energy levels and reveal the non-trivial topological modal structure exclusive to non-Hermitian systems. We also observe mode switching and a topological Berry phase for a parameter loop encircling the exceptional point. Our findings pave the way to studies of non-Hermitian quantum dynamics of exciton-polaritons, which may uncover novel operating principles for polariton-based devices.

doi: 10.1038/nature15522

The vulnerability of Indo-Pacific mangrove forests to sea-level rise p.559

Assessment of mangrove forest surface elevation changes across the Indo-Pacific coastal region finds that almost 70 per cent of the sites studied do not have enough sediment availability to offset predicted sea-level rise; modelling indicates that such sites could be submerged as early as 2070.

doi: 10.1038/nature15538

Hedgehog actively maintains adult lung quiescence and regulates repair and regeneration p.578

It is generally thought that the quiescence of tissue is not actively maintained, but rather a state reflecting the absence of proliferative signal; here the authors find that quiescence is actively maintained by paracrine hedgehog signalling provided by the epithelium in the mouse adult lung, and that hedgehog is dynamically regulated during injury repair and resolution for proper restoration of tissue homeostasis after injury.

doi: 10.1038/nature14984

Dynamic m6A mRNA methylation directs translational control of heat shock response p.591

The most abundant mRNA post-transcriptional modification is N6-methyladenosine (m6A), which has broad roles in RNA biology. In mammalian cells, the asymmetric distribution of m6A along mRNAs results in relatively less methylation in the 5′ untranslated region (5′UTR) compared to other regions. However, whether and how 5′UTR methylation is regulated is poorly understood. Despite the crucial role of the 5′UTR in translation initiation, very little is known about whether m6A modification influences mRNA translation. Here we show that in response to heat shock stress, certain adenosines within the 5′UTR of newly transcribed mRNAs are preferentially methylated. We find that the dynamic 5′UTR methylation is a result of stress-induced nuclear localization of YTHDF2, a well-characterized m6A ‘reader’. Upon heat shock stress, the nuclear YTHDF2 preserves 5′UTR methylation of stress-induced transcripts by limiting the m6A ‘eraser’ FTO from demethylation. Remarkably, the increased 5′UTR methylation in the form of m6A promotes cap-independent translation initiation, providing a mechanism for selective mRNA translation under heat shock stress. Using Hsp70 mRNA as an example, we demonstrate that a single m6A modification site in the 5′UTR enables translation initiation independent of the 5′ end N7-methylguanosine cap. The elucidation of the dynamic features of 5′UTR methylation and its critical role in cap-independent translation not only expands the breadth of physiological roles of m6A, but also uncovers a previously unappreciated translational control mechanism in heat shock response.

doi: 10.1038/nature15377