The uncertain dash for gas p.7

doi: 10.1038/516007a

Harsh reality p.7

doi: 10.1038/516007b

Look ahead p.8

doi: 10.1038/516008a

Ebola vaccine race begins p.15

doi: 10.1038/516015a

Artificial tracheas under scrutiny p.16

doi: 10.1038/516016a

Rival species recast significance of ‘first bird’ p.18

doi: 10.1038/516018a

Climate tinkerers thrash out a plan p.20

doi: 10.1038/516020a

Projects seek hidden effects of cancer drugs p.21

doi: 10.1038/516021a

Quantum computer quest p.24

doi: 10.1038/516024a

The fracking fallacy p.28

doi: 10.1038/516028a

Autophagy transcribed p.40

doi: 10.1038/nature13939

Controls on isotopic gradients in rain p.41

doi: 10.1038/516041a

A backup for bacteria p.42

doi: 10.1038/nature13938

Stars fight back p.44

doi: 10.1038/516044a

A molecular knife to dice depression p.45

doi: 10.1038/nature13942

Ultrafast imaging takes on a new design p.46

doi: 10.1038/516046a

Professional identity can increase dishonesty p.48

doi: 10.1038/nature14068

The good in fat p.49

doi: 10.1038/nature14070

β-catenin mediates stress resilience through Dicer1/microRNA regulation p.51

doi: 10.1038/nature13976

Deconstructing transcriptional heterogeneity in pluripotent stem cells p.56

doi: 10.1038/nature13920

Structure of the V. cholerae Na⁺-pumping NADH:quinone oxidoreductase p.62

doi: 10.1038/nature14003

Stellar feedback as the origin of an extended molecular outflow in a starburst galaxy p.68

doi: 10.1038/nature14012

Nonlinear lattice dynamics as a basis for enhanced superconductivity in YBa₂Cu₃O_6.5 p.71

Terahertz-frequency optical pulses can resonantly drive selected vibrational modes in solids and deform their crystal structures. In complex oxides, this method has been used to melt electronic order, drive insulator-to-metal transitions and induce superconductivity. Strikingly, coherent interlayer transport strongly reminiscent of superconductivity can be transiently induced up to room temperature (300 kelvin) in YBa₂Cu₃O_6+x (refs 9, 10). Here we report the crystal structure of this exotic non-equilibrium state, determined by femtosecond X-ray diffraction and ab initio density functional theory calculations. We find that nonlinear lattice excitation in normal-state YBa₂Cu₃O_6+x at above the transition temperature of 52 kelvin causes a simultaneous increase and decrease in the Cu–O₂ intra-bilayer and, respectively, inter-bilayer distances, accompanied by anisotropic changes in the in-plane O–Cu–O bond buckling. Density functional theory calculations indicate that these motions cause drastic changes in the electronic structure. Among these, the enhancement in the character of the in-plane electronic structure is likely to favour superconductivity.

doi: 10.1038/nature13875

Single-shot compressed ultrafast photography at one hundred billion frames per second p.74

doi: 10.1038/nature14005

Conductive two-dimensional titanium carbide ‘clay’ with high volumetric capacitance p.78

doi: 10.1038/nature13970

Eastern Pacific tropical cyclones intensified by El Niño delivery of subsurface ocean heat p.82

doi: 10.1038/nature13958

Business culture and dishonesty in the banking industry p.86

doi: 10.1038/nature13977

Inhibition of cell expansion by rapid ABP1-mediated auxin effect on microtubules p.90

doi: 10.1038/nature13889

An enteric virus can replace the beneficial function of commensal bacteria p.94

doi: 10.1038/nature13960

The ESCRT machinery regulates the secretion and long-range activity of Hedgehog p.99

doi: 10.1038/nature13847

Centriole amplification by mother and daughter centrioles differs in multiciliated cells p.104

doi: 10.1038/nature13770

Transcriptional regulation of autophagy by an FXR–CREB axis p.108

doi: 10.1038/nature13949

Nutrient-sensing nuclear receptors coordinate autophagy p.112

doi: 10.1038/nature13961

TRIM37 is a new histone H2A ubiquitin ligase and breast cancer oncoprotein p.116

doi: 10.1038/nature13955

Piezo2 is the major transducer of mechanical forces for touch sensation in mice p.121

doi: 10.1038/nature13980

Physical mechanism for gating and mechanosensitivity of the human TRAAK K⁺ channel p.126

Activation of mechanosensitive ion channels by physical force underlies many physiological processes including the sensation of touch, hearing and pain. TRAAK (also known as KCNK4) ion channels are neuronally expressed members of the two-pore domain K+ (K2P) channel family and are mechanosensitive. They are involved in controlling mechanical and temperature nociception in mice. Mechanosensitivity of TRAAK is mediated directly through the lipid bilayer—it is a membrane-tension-gated channel. However, the molecular mechanism of TRAAK channel gating and mechanosensitivity is unknown. Here we present crystal structures of TRAAK in conductive and non-conductive conformations defined by the presence of permeant ions along the conduction pathway. In the non-conductive state, a lipid acyl chain accesses the channel cavity through a 5 Å-wide lateral opening in the membrane inner leaflet and physically blocks ion passage. In the conductive state, rotation of a transmembrane helix (TM4) about a central hinge seals the intramembrane opening, preventing lipid block of the cavity and permitting ion entry. Additional rotation of a membrane interacting TM2–TM3 segment, unique to mechanosensitive K2Ps, against TM4 may further stabilize the conductive conformation. Comparison of the structures reveals a biophysical explanation for TRAAK mechanosensitivity—an expansion in cross-sectional area up to 2.7 nm2 in the conductive state is expected to create a membrane-tension-dependent energy difference between conformations that promotes force activation. Our results show how tension of the lipid bilayer can be harnessed to control gating and mechanosensitivity of a eukaryotic ion channel.

doi: 10.1038/nature14013