Reviews & Analysis

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.

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

A high-resolution crystal structure of the HIV-1 Env trimer proteins, in their form before they fuse with target cells, will aid the design of vaccines that elicit protective immune responses to this protein complex. See Article p.455

A newly constructed electron-energy monochromator for an atomic-resolution transmission electron microscope has resolved spectroscopic signatures of chemical-bond vibrations that are spatially highly localized. See Letter p.209

Studies of stencils and paintings from prehistoric caves in Indonesia date the art to at least 39,900 years ago — around the same age as the earliest cave art previously known, 13,000 kilometres away in western Europe. See Letter p.223

The nature of ultraluminous X-ray astronomical sources has long been unclear. The latest observations of these rare systems provide some crucial clues, but still leave theorists scratching their heads. See Letters p.198 & p.202

An ultrafast, temperature-dependent mode of endocytosis, a process that is required for neurons to repeatedly fire, challenges current thinking and brings an old model back into the spotlight. See Article p.228

A measurement of the mass of the heftiest-known elementary particle, the top quark, which exists for less than a trillionth of a trillionth of a second, sheds light on the ultimate fate of our Universe, although ambiguities cloud its interpretation.

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

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

The adoption of a new form of tool use has been observed to spread along social-network pathways in a chimpanzee community. The finding offers the first direct evidence of cultural diffusion in these animals in the wild.

The cloud that emerged above the south pole of Saturn's moon Titan in 2012 has been found to consist of hydrogen cyanide particles. This unexpected result prompts fresh thinking about the atmosphere of this satellite. See Letter p.65

Observations of the water pressure in drilled boreholes and natural moulins on the Greenland Ice Sheet show how its underlying plumbing system controls ice motion during the course of the summer melt season. See Letter p.80

A study finds that the cells lining the gut are modified in response to systemic infection, increasing the host's tolerance to infection in a manner that is dependent on the microorganisms that inhabit the gut. See Letter p.638

Transplanting gene-corrected macrophage cells directly into the lungs of mice has been shown to effectively treat their pulmonary alveolar proteinosis, a hereditary lung disease also found in humans. See Article p.450

An infrared census of accreting supermassive black holes across a wide range of cosmic times indicates that the canonical understanding of how these luminous objects form and evolve may need to be adjusted.

An analysis of the combined genomes of microorganisms inhabiting human skin demonstrates how these communities vary between individuals and across body sites, and paves the way to understanding their functions. See Article p.59