Letters in 2012

A combination of structural, computational and biophysical tools is used to characterize the bond between tip-link proteins protocadherin 15 and cadherin 23, which have an essential role in inner-ear mechanotransduction; the bond, involving an extended protein handshake, is found to be affected by deafness mutations and is mechanically strong enough to resist forces in hair cells, adding to our understanding of hair-cell sensory transduction and interactions among cadherins.

Whereas space weathering of some airless bodies, such as the Moon, occurs through the accumulation on regolith of nanophase metallic particles, spectroscopic data show that space weathering of the asteroid Vesta occurs through the small-scale mixing of diverse surface components, which gradually generates locally homogenized upper regolith.

The identification of two superluminous supernovae at redshifts of 2.05 and 3.90 extends the present technological redshift limit on supernova detection and presents the possibility of studying the deaths of the first stars to form after the Big Bang.

The authors analyse the tempo and geography of diversification for all 10,000 species of birds: diversification has sped up over time, bursts are spread out across the tree and across the world, and high rates are not concentrated in the tropics.

Laboratory experiments and seismological observations show that increased fault healing causes a disproportionately large amount of high-frequency seismic radiation to be produced during fault rupture, which may help to explain recent observations of large megathrust earthquakes.

This study presents a new model for the regulation of nitric oxide signalling in endothelial cells; the oxidation state of endothelial haemoglobin α, controlled by cytochrome B5 reductase 3, regulates nitric oxide bioactivity and diffusion towards its vascular smooth muscle targets.

From spectra and images of Vesta, it is suggested that the dark patches on Vesta are formed of infalling hydrated carbonaceous material and the bright patches are uncontaminated Vesta soil.

High-resolution, in situ imaging of Rydberg atoms in a Mott insulator reveals the emergence of spatially ordered excitation patterns with random orientation but well-defined geometry.

The crystal structure of the Mediator head module from the fission yeast Schizosaccharomyces pombe is solved at 3.4 Å resolution.

A meta-analysis of previous genome-wide association studies of Crohn’s disease and ulcerative colitis, the two most common forms of inflammatory bowel disease, with a combined total of more than 75,000 cases and controls, finds that most loci contribute to both phenotypes and other immune-mediated disorders.

Individuals with the red hair/fair skin phenotype usually carry a polymorphism in the gene encoding the melanocortin 1 receptor (Mc1r) that results in the production of pigment containing a high pheomelanin-to-eumelanin ratio; here it is shown in a mouse model that inactivation of Mc1r promotes melanoma formation in the presence of the Braf oncogene, thus suggesting that pheomelanin synthesis is carcinogenic by an ultraviolet-radiation-independent mechanism.

Excesses of ¹⁴²Nd previously found in 3.7-billion-year-old rocks from Isua, southwest Greenland, imply their derivation from a depleted mantle formed in the Hadean eon; the signature of a complementary Hadean enriched reservoir is now reported in 3.4-billion-year-old mafic dykes found in Isua.

Examination of spatial representations in the entorhinal cortex of monkeys performing a visual memory task reveals individual neurons that emit action potentials when the monkey fixates multiple discrete locations in the visual field, and suggests that entorhinal cortex neurons encode space during visual exploration, even without locomotion.

Neurons and oligodendrocytes differentiated from induced pluripotent stem cells (iPSCs) of patients with inherited TLR3 and UNC-93B deficiencies are found to be more susceptible to infection by HSV-1 than control cells because they fail to induce a normal interferon response, whereas neural stem cells and astrocytes are not susceptible.

The interaction between IgE and its receptor FcεRI underlies many allergic responses; here the structure and mechanism of a newly engineered DARPin inhibitor is presented, revealing that it not only blocks the receptor–ligand interaction but also dissociates already-formed complexes.

Dendritic spines operate as high-impedance input structures that amplify local synaptic depolarization to enhance electrical interaction among coactive inputs.

Dopamine is synonymous with reward in mammals but associated with aversive reinforcement in insects, where reward seems to be signalled by octopamine; here it is shown that flies have discrete populations of dopamine neurons representing positive or negative values that are coordinately regulated by octopamine.

Seismic data and modelling are used to reveal clathrate destabilization along the eastern margin of the United States; the destabilization is probably linked to warming, or a slight shift, in the Gulf Stream.

The synthesis of an all-carbon quaternary stereocentre in an acyclic system is reported; the chemical transformation involves the formation of two new stereogenic centres—including the challenging all-carbon quaternary one in an aldol adduct—via a combined carbometalation–oxidation reaction, giving a stereodefined trisubstituted enolate.

The fluvial response in western Colorado to the Palaeocene/Eocene thermal maximum involves a large increase in sediment flux that lasted much longer than the vegetation, monsoon and carbon dioxide changes of the thermal maximum.