Reviews & Analysis

After spinal-cord injury, cells called astrocytes form a scar that is thought to block neuronal regeneration. The finding that the scar promotes regrowth of long nerve projections called axons challenges this long-held dogma. See Article p.195

Processes such as photosynthesis depend on the interplay between the electric dipoles of chromophore molecules. Yet these dipole–dipole interactions have not been visualized at the atomic level — until now. See Letter p.623

An analysis of changes in island topography and climate that have occurred since the last glacial maximum 21,000 years ago shows how sea-level change has influenced the current biodiversity of oceanic islands. See Letter p.99

The discovery of a modified version of the base adenine, known as N⁶-methyladenine, in mouse DNA puts paid to the theory that cytosine derivatives are the only modified bases in mammals. See Article p.329

A meta-analysis of 143 bird species finds huge variation in parental responses to chicks' begging signals, and shows that parental strategies depend on environmental factors, such as the predictability and quality of food supplies.

Alkenyl halides are some of the most useful building blocks for synthesizing small organic molecules. A catalyst has now allowed their direct preparation from widely available alkenes using the cross-metathesis reaction. See Article p.459

In rats, individual differences in risk preference and in sensitivity to gains compared with losses are controlled by a specific neuronal population, stimulation of which neutralizes risk-seeking behaviour. See Letter p.642

The presence of ice at two positions on opposite sides of the Moon suggests that the satellite's orientation was once shifted away from its present spin axis — a finding that has implications for the Moon's volcanic history. See Letter p.480

A high-throughput approach has found clusters of DNA double-strand breaks in neural cells. Most of the clusters are in large genes that are associated with neural function, which suggests that the breaks may have tissue-specific roles.

A clever dissection of the roles of the Ptchd1 gene in the brains of mice demonstrates one way to untangle the complex relationships between the causes and symptoms of neurodevelopmental disorders. See Article p.58

Migratory birds are declining globally. A broad study of European migratory birds finds that species that disperse widely during the non-breeding season are less likely to be in decline than are species with more restricted dispersion.

Organelles called primary cilia that protrude from cells have been thought to sense the surrounding environment through calcium-channel proteins that respond to force. Two scientists discuss the implications for developmental biology and kidney disease of a study that challenges this hypothesis. See Letter p.656

Microscopy reveals how nanowires of a widely used semiconductor grow during preparation. The findings will allow the crystal phases of such nanowires to be engineered — a crucial advance for materials science. See Article p.317

Scientists have created soft microrobots whose body shapes can be controlled by structured light, and which self-propel by means of travelling-wave body deformations similar to those exhibited by swimming protozoa.

The HBx protein of hepatitis B virus has been found to co-opt a host-cell enzyme that targets the Smc5/6 protein complex for degradation. The finding identifies Smc5/6 as a cellular antiviral factor. See Letter p.386

Increasing cholesterol levels in the cell membranes of killer T cells boosts the cells' ability to mount an immune response against tumour cells in mice. Such a strategy might be valuable in anticancer immunotherapies. See Letter p.651

Enhancing synaptic connections between neurons in the brain's hippocampus that are normally activated during memory formation rescues memory deficits in a mouse model of early Alzheimer's disease. See Letter p.508

The finding that marine environments with high levels of host microbes have fewer viruses per host than when host abundance is low challenges a theory on the relative roles of lysogenic and lytic viral-survival strategies. See Article p.466