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CD8⁺ memory cytotoxic T lymphocytes need help from CD4⁺ T cells to undergo secondary expansion but the mechanisms of help are not fully understood. Here, it is shown that, after activation by CD4⁺ T cells, antigen-presenting cells activate CD8⁺T cells via the CD70/CD27 co-stimulatory pathway.

The exact mechanism for superconductivity in iron-based superconductors remains elusive, but is thought to involve complex interactions between many orbitals. Using angle-resolved photoelectron spectroscopy, Liuet al. report the electronic structure of the single-layer parent compound FeSe.

Single electron pumps have been proposed as potential candidates for redefining the ampere. This study reports measurements of the quantized current flowing through a semiconductor electron pump with a precision that makes a substantial step towards establishing a direct metric for electrical currents.

The ability to manipulate single charges is a key requisite for novel nanoelectronic devices. Allenet al. show how to electrostatically confine electrons in suspended bilayer graphene quantum dots by local control of the graphene band structure.

The SrTiO₃/LaAlO₃ system is widely studied because it forms a two-dimensional electron gas at the interface. This study investigates the effects of diluting the LaAlO₃ layer with SrTiO₃, and finds that the threshold thickness required for the onset of conductivity scales inversely with the fraction of LaAlO₃, suggesting an intrinsic origin for the electron gas.

Switches made up of single molecules form the basis for the concept of molecular electronics. Miyamachiet al.demonstrate that an iron-based spin crossover molecule can be switched between different spin states, provided it is decoupled from a metallic substrate by a thin insulating layer.

Absorption imaging relies on the capture of photons by an object to create intensity contrasts, allowing for the visualization of small quantum systems. Streedet al. demonstrate the first absorption imaging of an isolated ytterbium ion, with contrast at the limit of semiclassical theory.

The activity of the Acid sensing ion channel 1, ASIC1, can be modulated by the gating modifier Psalmotoxin 1 but the molecular mechanism is unclear. Dawsonet al. report the structure of chicken ASIC1 bound to Psalmotoxin 1 and find that the toxin locks two regulatory regions of the channel into a desensitized conformation.

Plant hormones, such as auxin, coordinate plant development. In this study, an auxin transporter—PIN8—that is expressed in the male gametophyte ofArabidopsis thaliana, is found to regulate cellular homoeostasis and maintain optimal levels of auxin for pollen development.

Theory states that sterile worker bees compensate for a lack of direct fitness by contributing to the nest, but testing this has been difficult. Here, for the solitary and eusocial beeL. baleicum, the inclusive fitness of an eusocial worker is higher than that of a solitary female, satisfying the rule in the field.

To describe the biochemical composition of an organism multiple data sets must be combined and this information can then be used forin silico analysis. By combining metabolism and transcription data, Lerman et al. discovered new regulons and improved the gene annotation for the simple organism Thermotoga maritima.

In response to stress, yeast cells selectively translate proteins that can enhance cell survival. In this study, the authors find that tRNA^LEU(CAA)in yeast cells is modified in response to oxidative stress by a methyltransferase and this results in the selective translation of the mRNA for these genes.

The crystallization of a racemate on a surface can lead to crystals with a unit cell containing both enantiomers, or to the separation of enantiomers into crystals of single-handedness. This study shows that manganese co-absorbed with a quinone derivative leads to achiral islands, while co-absorption with caesium gives chiral islands.

Scanning probe microscopy and related techniques rely on the availability of very sharp tips. Here, a sharpening technique based on field-directed sputtering is demonstrated, resulting in ultrasharp metallic tips for use in scanning tunnelling microscopy as well as atomic-scale lithographic experiments.

The interface within heterostructures consisting of LaAlO₃ and SrTiO₃ has been reported to give rise to magnetism, in addition to a two-dimensional electron gas. Kalisky et al. observe that magnetism can occur only above a critical thickness, and that it occurs in heterogeneous patches.

Controlling nuclear spin patterns is important to manage decoherence and control electron spin currents in spintronic devices. This study demonstrates the optical creation of rewritable patterns of nuclear polarization in gallium arsenide without ferromagnets, lithographic patterning or field gradients.

The rice pattern recognition receptor—XA21—confers immunity against the Gram-negative bacterial pathogen,Xanthomonas oryzae pv. oryzae. This study shows that the intracellular kinase domain of XA21 translocates to the nucleus and that this translocation is essential for the XA21-mediated immune response.

Embryonic stem cells have a shortened cell cycle that allows for rapid proliferation, but the exact mechanisms are unclear. Here, a microRNA target, Trim71, is shown to inhibit the expression of a cyclin-dependent kinase inhibitor, thus enabling the G1–S phase cell cycle transition in embryonic stem cells.

Fast rechargeable batteries made from low-cost and abundant electrode materials are attractive for energy storage. Wanget al. develop an ultrafast Ni–Fe battery with carbon/inorganic hybrid electrodes in which the charge and discharge rates are nearly 1,000-fold higher than traditional Ni–Fe batteries.

Ganoderma lucidumis a macrofungus in traditional Chinese medicine known to produce different bioactive compounds. In this study, the genome ofG. lucidumis sequenced, making this organism a potential model system for future studies of secondary metabolic pathways and their regulation in medicinal fungi.