Research articles

Lymphomas often contain translocations that link c-myc to the immunoglobulin heavy chain locus (encoded by Igh), but the nature of the elements that activate oncogenes within such translocations is unknown. Transgenic mice with Igh 3' regulatory region (Igh3' RR) sequences fused to c-myc are predisposed to B lymphomas. Here, the oncogenic role of the Igh3' RR is investigated by inactivating it in two distinct mouse models for B-cell lymphoma with Igh–c-myc translocations.

All hard, convex shapes pack more densely than spheres, although for tetrahedra this was demonstrated only very recently. Here, tetrahedra are shown to pack even more densely than previously thought. Thermodynamic computer simulations allow the system to evolve naturally towards high-density states, showing that a fluid of hard tetrahedra undergoes a first-order phase transition to a dodecagonal quasicrystal, and yielding the highest packing fractions yet observed for tetrahedra.

Male animals are typically more elaborately ornamented than females, probably because females make more of an energetic investment in raising young. However, this generality may not apply in cooperatively breeding vertebrates, where the energetic load is similar in males and females. The socially diverse African starlings are now used to study this issue, revealing that where intrasexual competition among females may be intense, female trait elaboration is selected for.

Here, the link between non-coding RNA and chromatin regulation is investigated through analysis of FLC — a regulator of flowering time in Arabidopsis and a target of several chromatin pathways. FLC is silenced by prolonged cold in a Polycomb-mediated process called vernalization. Upregulation of long non-coding antisense transcripts covering the entire FLC locus are now suggested to have an early role in the cold-induced silencing mechanism.

The nature of the jets and the role of magnetic fields in gamma-ray bursts (GRBs) remain unclear. There are two possible models, one of which suggests that magnetic fields are critical; to distinguish between these models the degree of polarization in early-time emission must be measured. The early optical emission from GRB 090102 is now reported to be polarized at 10 ± 1 per cent, indicating the presence of large-scale fields originating in the expanding fireball.

5.33 million years ago, in an event known as the Zanclean flood, Atlantic waters refilled a mostly desiccated Mediterranean Sea which had become disconnected from the world's oceans; however, the nature, abruptness and evolution of this flood remain poorly constrained. Using borehole and seismic data and a model study, it is now suggested that 90 per cent of the water was transferred in a short period of a few months to two years, with peak rates of sea level rise in the Mediterranean possibly reaching more than 10 metres per day.

The atomic ratio of carbon:nitrogen:phosphorus can be used to describe biota in terms of elemental composition, and this stoichiometry is fundamental for understanding the production dynamics and biogeochemical cycles of ecosystems. Heterotrophic microbial communities from terrestrial soils and fresh-water sediments are now shown to share a common functional stoichiometry in relation to organic nutrient acquisition, reflecting the similar scaling relationships of four key ecoenzymes.

Seismic detectability of the boundaries and convection in the mantle is strongly influenced by the thicknesses and Clapeyron slopes of mantle phase boundaries. The unusually large positive Clapeyron slope found for the boundary between perovskite and post-perovskite (the 'pPv boundary') would destabilize high-temperature anomalies in the lowermost mantle, in disagreement with the seismic observations. Here, new studies of the thickness and Clapeyron slope of the pPv boundary shed light on this matter.

Alanyl-tRNA synthetases (AlaRSs) may confuse glycine or serine with alanine, potentially causing mistranslation and thus profound functional consequences, with serine posing a bigger challenge than glycine. AlaXps — free-standing, genome-encoded editing proteins — represent one editing checkpoint to prevent this from occurring. Nine crystal structures, together with kinetic and mutational analysis, now show how AlaXps solve the serine misactivation problem.

In living systems, the repair of genotoxic damage requires that the lesion first be detected in an excess of undamaged DNA. A base-excision DNA repair enzyme, MutM, is now captured and structurally elucidated at the stage of initial encounter with a damaged nucleobase within a DNA duplex. By combining structural biology and computational modelling, the pathway by which this encounter causes the damaged nucleobase to be extruded from the DNA duplex is defined.

Chiral spin liquids are a hypothetical class of spin liquids in which time-reversal symmetry is macroscopically broken even in the absence of an applied magnetic field or any magnetic dipole long-range order. Although such spin-liquid states were proposed more than two decades ago, they remain elusive. Here, evidence is presented that the time-reversal symmetry can be broken spontaneously on a macroscopic scale in the absence of magnetic dipole long-range order, suggesting the emergence of a chiral spin liquid.

The Red Queen metaphor has species accumulating small changes to keep up with a continually changing environment, with speciation occurring at a constant rate. This constant-rate claim is now tested against four competing models, using 101 phylogenies of animal, plant and fungal taxa. The results provide a new interpretation of the Red Queen; a view linking speciation to rare stochastic events that cause reproductive isolation.

Placing a macroscopic object in its quantum-mechanical ground state of motion is an exciting experimental target that should reveal counterintuitive physical behaviour — such as the existence of states in which the mechanical system is located in two places simultaneously. A nanomechanical resonator is now cooled to a point where the probability of its residing in the quantum ground state of motion is 0.21; this level of cooling should allow a series of fundamental quantum mechanical observations.

During reconsolidation of memories, stored information is rendered labile after being retrieved and can be manipulated. Previous studies have used pharmacological intervention to disrupt retrieved memories; here, however, a non-invasive, behavioural technique is used to target the reconsolidation of fear memories in humans. Non-fearful information provided during the reconsolidation window appears to update old fear memories, causing a lack of expression of fear responses.

Stomata are specialized structures in the epidermal layer of leaves that regulate the exchange of gases between the plant and the atmosphere. One or more positive intercellular signalling factors are assumed to be involved in stomatal development, but their identities remain elusive. A novel secretory protein — named stomagen — is now shown to be just such a factor; it is conserved among vascular plants and positively regulates stomatal density.

Evidence from animal studies shows that testosterone can induce aggressive behaviour, but whether this extrapolates to humans is an area of debate. The sublingual administration of a single dose of testosterone in women is now shown to cause a substantial increase in fair bargaining behaviour, although subjects who believed they received testosterone behaved much more unfairly than those who thought they received a placebo.

Although aggression is known to be regulated by pheromones in many animal species, in no system have the pheromones, their receptors and corresponding sensory neurons been identified. Here, 11-cis-vaccenyl acetate (cVA), a volatile pheromone produced by male fruitflies, is shown to promote male-to-male aggression through the activation of olfactory sensory neurons expressing the receptor Or67d.

The contribution of copy number variation to obesity — a highly heritable and genetically heterogeneous disorder — is investigated in 300 Caucasian patients to reveal that large, rare deletions are significantly enriched in patients compared to controls. Several rare copy number variants are identified that are recurrent in patients but absent or at much lower prevalence in controls.