Research articles

WebX-ray crystal structures are presented of each major step of the assembly-line synthesis by the initiation module of the nonribosomal peptide synthetase (NRPS) LgrA; the structures reveal large conformational changes, demonstrating a requirement for NRPSs to be very dynamic.

Using infrared wavelengths, micrometre-sized water-ice grains have been identified on the nucleus (which is mostly coated in a dark material) of comet 67P/Churyumov–Gerasimenko.

In-depth analyses of protein expression studies are used to derive a new codon-influence metric that correlates with global protein levels, mRNA levels and mRNA lifetimes in vivo, indicating tight coupling between translation efficiency and mRNA stability; genes redesigned based on these analyses consistently yield high protein expression levels both in vivo and in vitro.

X-ray crystal structures of two distinct steps in the catalytic cycle of non-ribosomal peptide synthetases are described, offering the potential to generate novel products through engineering enzyme activity.

New excavations in Sulawesi, where in situ stone artefacts associated with fossil remains of megafauna have been recovered from stratified deposits between 200,000 and 100,000 years ago, suggest that Sulawesi was host to a long-established population of archaic hominins.

Ischaemia damages nerve myelin by depriving neurons and their myelinating oligodendrocytes of oxygen and glucose; here it is shown that ischaemic damage is caused through the H⁺-dependent activation of TRPA1 channels, and not via glutamate receptors of the NMDA type, as previously thought, providing a new mechanism and promising therapeutic targets for diseases as diverse and prevalent as cerebral palsy, spinal cord injury, stroke and multiple sclerosis.

Far-ultraviolet observations of the nearby low-mass star-forming galaxy J0925+1403 show that the galaxy is leaking ionizing radiation with an escape fraction of about 8 per cent, which is sufficient to ionize intergalactic medium material that is about 40 times as massive as the stellar mass of the galaxy.

Epithelial tuft cells secretion of IL-25 is shown to regulate type 2 epithelial responses to helminth parasite infection via an IL-13/IL-4Rα-dependent feedback loop.

WebMotor neurons in zebrafish are shown to be more than simply output neurons, since they are able to influence, through gap junctions, the strength of the input they receive from V2a interneurons and, thereby, the frequency and duration of locomotor activity.

In mice on a low microbiota-accessible carbohydrate (MAC) diet, the diversity of the gut microbiota is depleted, and the effect is transferred and compounded over generations; this phenotype is only reversed after supplementation of the missing taxa via faecal microbiota transplantation, suggesting dietary intervention alone may by insufficient at managing diseases characterized by a dysbiotic microbiota.

To address the question of whether a recurrent tumour is genetically similar to the tumour at diagnosis, the evolution of medulloblastoma has been studied in both an in vivo mouse model of clinical tumour therapy as well as in humans with recurrent disease; targeted tumour therapies are usually based on targets present in the tumour at diagnosis but the results from this study indicate that post-treatment recurring tumours (compared with the tumour at diagnosis) have undergone substantial clonal divergence of the initial dominant tumour clone.

Lithium–oxygen batteries allow oxygen to be reduced at the battery’s cathode when a current is drawn; in present-day batteries, this results in formation of Li₂O₂, but it is now shown that another high energy density material, namely LiO₂, with better electronic conduction can be used instead as the discharge product, if the electrode is decorated with iridium nanoparticles.

Quantum entanglement is thought to offer great promise for improving measurement precision; now a spin-squeezing implementation with cold atoms offers levels of sensitivity unavailable with any competing conventional method, sensing microwave induced rotations a factor of 70 beyond the standard quantum limit.

In mouse embryonic stem cells converted to an epiblast fate in vitro—a state in which the cells can also gain germ cell fate if exposed to the signalling molecule BMP4—the sole expression of the transcription factor NANOG is shown to be sufficient to induce germ cell fate, in the absence of BMP4.

Raman spectroscopy of three isotopes of hydrogen under very high compression yields evidence of a new phase of hydrogen—phase V—which could potentially be a precursor to the long-sought non-molecular phase.

Electroreduction of carbon dioxide into useful fuels helps to reduce fossil-fuel consumption and carbon dioxide emissions, but activating carbon dioxide requires impractically high overpotentials; here a metal atomic layer combined with its native oxide that requires low overpotentials to reduce carbon dioxide is developed, adapted from an existing cobalt-based catalyst.

Analyses of the effects of extreme weather disasters on global crop production over the past five decades show that drought and extreme heat reduced national cereal production by 9–10%, whereas no discernible effect at the national level was seen for floods and extreme cold; droughts affect yields and the harvested area, whereas extreme heat mainly affects yields.

Both DNA and RNA molecules have been shown to exhibit catalytic activity, but only the structure of catalytic RNAs has previously been determined; here the structure of an RNA-ligating DNA in the post-catalytic state is solved.

A high-fidelity variant of Streptococcus pyogenes CRISPR–Cas9 is reported that lacks detectable off-target events as assessed by genome-wide break capture and targeted sequencing methods.

Experiments show that carbonated oceanic crust subducting into the mantle will intersect the melting curve at depths of about 300 to 700 kilometres, creating a barrier to direct carbonate recycling into the deep mantle.