Review, News & Views, Perspectives, Hypotheses and Analyses in 2013

A study shows that, rather than sequentially starting and stopping a movement, two parallel pathways involving neurons in the brain's basal ganglia seem to work in tandem to accomplish the complex task of motion. See Letter p.238

A comparison of the wearing effect of plant-derived silica and desert dust on tooth enamel suggests that extreme wear on teeth might not be caused by food. The findings may change some thoughts about the diets of human ancestors.

Two studies shed light on the role of cellular transitions between the epithelial and mesenchymal states during cancer metastasis, and provide food for thought as to which cellular processes should be targeted in cancer treatment.

Brush-like polymers with a rigidity similar to that of polymers in living cells have been synthesized and used to build force-responsive materials. The advance opens the door to applications in drug delivery and tissue engineering. See Letter p.651

The spliceosome complex removes intron sequences from RNA transcripts to form messenger RNA. The structure of a spliceosomal protein, Prp8, reveals the complex's active site and casts light on the origin of splicing. See Article p.638

Determining the real scale of structures in the Sun's corona has proved difficult because of limited spatial resolution. Now high-resolution imaging has allowed dynamic structures on scales of 150 kilometres to be observed. See Letter p.501

The use of confocal fluorescence microscopy to image defects in crystalline, porous solids known as metal–organic frameworks enables the relationship between the number of defects and the materials' properties to be determined.

Cellular reprogramming to a stem-cell-like state is inefficient and poorly understood, despite its biomedical potential. Detailed molecular analyses of this process are now reported, and should help to overcome these limitations.

An analysis shows that fuel made from wild, herbaceous vegetation grown on land currently unsuitable for cultivating field crops could contribute substantially to the United States' targets for biofuel production. See Letter p.514

A state-of-the-art numerical model shows that the advance of glaciers in a cooling climate depends strongly on the pre-existing landscape, and that glacial erosion paves the way for greater glacial extent in the future. See Letter p.206

Fossils of microorganisms from deep-sea sediment cores show that environmental change correlates closely with extinction but not with speciation, producing a nuanced view of the drivers of evolution. See Letter p.398

Physicists have come up with the mind-boggling concept of a time crystal. This intriguing proposal, which is based on the notion of broken time-translation symmetry, might open up a whole new field of research.

An array of more than 4,000 optical antennas working in unison has been demonstrated on a millimetre-scale silicon chip. The result highlights the remarkable capabilities of optical integration in silicon. See Letter p.195

Most fish living in marine reserves are older, bigger and more fecund than those outside their borders, but they are also slower to flee a threat. The potential for 'spillover' of such fish into fisheries may boost support for reserves.

The hormone insulin has a central role in human physiology, yet the answer to a fundamental biochemical question — how it binds to its cell-surface receptor — has remained elusive, until now. See Letter p.241

A method for dissecting the polymeric networks of gels enables the number of loops — strands that connect to themselves — within them to be counted. This allows network morphologies to be correlated with gel properties.

Magmas that have erupted at Earth's surface reveal a potential new mantle source. This source, which is rich in nickel and has a primordial helium isotopic content, may have originated at great depth in the mantle. See Letter p.393