Reviews & Analysis

Tumour spread is the main cause of death in patients with melanoma. Exposure of melanoma to ultraviolet radiation has now been found to cause an inflammatory response that drives the formation of distant metastases. See Letter p.109

The discovery of crystallographic imperfections known as disclinations in the most profuse mineral in Earth's upper mantle has the potential to solve a problem that has vexed mineral physicists for decades. See Article p.51

The protein NRT1.1 transports nitrate ions into plants over a wide range of concentrations. Two studies provide structural insight into this unusual behaviour, but give different explanations for it. See Articles p.68 & p.73

Observations of the supernova remnant Cassiopeia A offer an unprecedented look back at the centre of this explosion, and support the hypothesis that spatial asymmetry is key to explaining the event. See Letter p.339

A protein produced by endothelial cells that line blood vessels has been found to regulate the timing of cell proliferation following liver injury, further demonstrating the role of vascular signals in tissue regeneration.

A common variant of the autophagy protein ATG16L1 is a risk factor for Crohn's disease. But the genetic alteration is revealed only when the protein is cleaved by the enzyme caspase 3 during cellular stress. See Article p.456

Analyses of ependymoma brain tumours reveal a gene rearrangement in one subtype, but no DNA mutations in two others, suggesting that mechanisms for cancer initiation are broader than is typically thought. See Articles p.445 & p.451

A new value for the atomic mass of the electron is a link in a chain of measurements that will enable a test of the standard model of particle physics with better than part-per-trillion precision. See Letter p.467

The observation of path dependence in the response of a superfluid to stirring promises potential applications in precision rotation sensing, and provides a test bed for microscopic theories of ultracold atomic gases. See Letter p.200

The early development of acute leukaemias is assumed for the most part to be clinically silent and transient. But it now seems that ancestral precancerous cells are identifiable and persistent. See Article p.328

In advanced age, the stem cells responsible for muscle regeneration switch from reversible quiescence to irreversible senescence. Targeting a driver of senescence revives muscle stem cells and restores regeneration. See Article p.316

The whole-genome sequence of a human associated with the earliest widespread culture in North America confirms the Asian ancestry of the Clovis people and their relatedness to present-day Native Americans. See Letter p.225

Ribosomes, the cell's protein-synthesis machines, are assembled from their components in a defined order. It emerges that the first assembly step must overcome dynamic structural rearrangements. See Article p.334

Experiments conducted at the US National Ignition Facility have cleared a hurdle on the road to nuclear fusion in the laboratory, encouraging fusion scientists around the world. See Letter p.343

An analysis reveals that satellite-observed increases in canopy greenness during dry seasons, which were previously interpreted as positive responses of Amazon forests to more sunlight, are in fact an optical artefact. See Letter p.221

Aircraft have captured the 'breath' of the Amazon forest — carbon emissions over the Amazon basin. The findings raise concerns about the effects of future drought and call for a reassessment of how fire is used in the region. See Letter p.76

Oily substances in the skin have now been shown to contain structures that activate a population of skin-homing, self-reactive T cells. The responses of these immune cells may contribute to local defences, but also to autoimmune disease.

By separately scattering right- and left-handed electrons off quarks in a deuterium target, researchers have improved, by about a factor of five, on a classic result of mirror-symmetry breaking from 35 years ago. See Letter p.67