Articles in 2012

Epigenetic modifications are thought to affect the accessibility of DNA, but it is not clear whether this is a universal effect. These authors map DNA accessibility inArabidopsis thalianaand find that, in contrast to fruitflies, H3K9 dimethylation reduces accessibility in a DNA methylation-dependent manner.

Organic electronic materials are promising candidates for applications in which flexible electronic devices are required. Yiet al. demonstrate a high-performance, flexible organic transistor based on solution-processed small molecules that can be fabricated with a simple, low-cost process.

Back pain and sciatica are often caused by intervertebral disc degeneration. Sakai and colleagues identify a subset of nucleus pulposus progenitor cells from the intervertebral disc and show that loss of these progenitor cells correlates with ageing and intervertebral disc degeneration.

Proteins are integrated into cellular membranes either co-translationally through Sec/SRP or post-translationally by chaperones. These authors show that an integration-dedicated chaperone inE. coli, MPIase, is a glycolipid and facilitates protein insertion into the inner membrane of the bacterium.

ErbB2 is a receptor tyrosine kinase that localizes to the plasma membrane. Dinget al. now show that ErbB2 also localizes to mitochondria, where it regulates mitochondrial respiratory function and resistance to cancer chemotherapy.

Heterogeneous composite materials, which are potentially useful for flexible electronics, are widespread in nature but synthetic examples are rare. Here, a site-specific hierarchical approach is used to fabricate composites with extreme local variations in elastic modulus and which are reversibly stretchable.

RNA viruses are known to rapidly evolve new features through errors in replication and reshuffling of genomic segments. These authors report another strategy used by the measles virus to improve infectivity; the cooperation between wild-type and mutant fusion proteins in the same viral particle.

The transition metal-catalysed reduction of nitrogen, vital for the production of fertilizer, usually requires expensive molybdenum catalysts. Here, Yuki et al.describe the iron-catalysed reduction of nitrogen under ambient conditions and propose a reaction pathway supported by DFT calculations.

Multilayer graphene is a promising electronic material because of its tunable band structure and pseudospin properties. Campos et al.show giant conductance oscillations in a ballistic trilayer graphene Fabry-Pérot interferometer that can be suppressed both classically and quantum mechanically.

The frictional force required to move a liquid drop on a surface is known to depend upon the drop resting time. N'guessan et al. demonstrate that water drops on graphene surfaces are an exception, which is attributable to the chemical homogeneity and stability of graphene surfaces.

The exploitation of the properties of graphene, such as mechanical strength and electrical conductivity, in deformable macroscopic materials is desirable. Here, a combination of graphene chemistry and ice physics is used to fabricate biomimetic, ultralight and superelastic graphene cellular monoliths.

Biological structures such as the backs of beetles and spider silk have fog-collecting properties. Here, clusters of conical spines and trichomes on the stem of the cactus O. microdasysare found to be responsible for its fog-collecting abilities.

Polariton condensates provide an arena in which to study interesting non-equilibrium condensate dynamics. Tosi et al. generate stable vortex lattices in a polariton condensate and study their macroscopic wavefunction, uncovering a nonlinear regime for topological defects at high densities.

The dentate gyrus and CA3 of the hippocampus are involved in pattern separation. Niibori and colleagues investigate the role of adult hippocampal neurogenesis in pattern separation and find that suppressing adult neurogenesis in the dentate gyrus impairs coding of similar, but not dissimilar contexts.

While human embryonic stem cells (ESC) hold great therapeutic promise, many aspects of their basic biology remain poorly understood. Conklin et al.show that too much or too little activation of RB family proteins is detrimental to human ESC populations and identify unique cell cycle regulatory networks in these cells.

Cholesterol indirectly regulates intracellular signalling by modulating the physical properties of lipid membranes. Sheng et al.now show that many PDZ domains contain a functional cholesterol-binding motif, revealing that cholesterol can also control the localization and function of signalling proteins directly.

The amount of data supplied by next-generation sequencing technologies presents a challenge for traditional algorithms to detect single-nucleotide polymorphisms. Xu et al.develop an efficient detection program and demonstrate its utility by identifying polymorphisms in cancer genomes and human populations.

Despite the central importance of NADP⁺ in mitochondrial energy metabolism, no NAD kinase has been found in human mitochondria to synthesize NADP⁺. These authors show C5orf33, a protein specific to animals and protists, to be the missing NAD kinase and demonstrate its mitochondrial localization and activity.

The use of animal products as culture substrates for human embryonic stem cell and induced pluripotent stem cell culture raises numerous safety concerns in a therapeutic setting. Miyazaki et al.. show that minimal fragments of human laminins provide a more effective support for the culture of these cell types.

The gut microbiota has emerged as an environmental factor that can influence the development of obesity and diabetes. Here, Karlsson et al. report compositional and functional alterations of the gut metagenome in patients with symptomatic atherosclerosis.