Volume 553 Number 7688

Editorials

News

News Features

News & Views

Mice learn to avoid the rat race p.284

Mice can learn to overcome their naturally aggressive approach to conflict resolution, instead adopting a cooperative strategy. This discovery provides a simple animal model in which to investigate a complex social behaviour.

doi: 10.1038/d41586-017-08835-9

Pathogens boosted by food additive p.285

Epidemic strains of the bacterium Clostridium difficile have now been found to grow on unusually low levels of the food additive trehalose, providing a possible explanation for C. difficile outbreaks since 2001.

doi: 10.1038/d41586-017-08775-4

Strategy for making safer opioids bolstered p.286

Compounds have been made that activate only the G-protein signalling pathway when bound to the μ-opioid receptor — the target of opioid pain relievers. These compounds lack one of the main side effects of currently used opioids.

doi: 10.1038/d41586-018-00045-1

Homing in on a key factor of climate change p.288

The sensitivity of Earth’s climate to atmospheric carbon dioxide levels is a big unknown in predicting future global warming. A compelling analysis suggests that we can rule out high estimates of this sensitivity.

doi: 10.1038/d41586-018-00480-0

Limitless translation limits translation p.289

Evidence has now been found that ribosomes — the cell’s translational apparatus — can pass beyond the main protein-coding region of messenger RNAs to form ‘traffic jams’ that inhibit protein expression.

doi: 10.1038/d41586-017-08785-2

Articles

Dietary trehalose enhances virulence of epidemic Clostridium difficile p.291

Two hypervirulent ribotypes of the enteric pathogen Clostridium difficile, RT027 and RT078, have independently acquired unique mechanisms to metabolize low concentrations of the disaccharide trehalose, suggesting a correlation between the emergence of these ribotypes and the widespread adoption of trehalose in the human diet.

doi: 10.1038/nature25178

Letters

Large granulation cells on the surface of the giant star π1 Gruis p.310

Convection plays a major part in many astrophysical processes, including energy transport, pulsation, dynamos and winds on evolved stars, in dust clouds and on brown dwarfs. Most of our knowledge about stellar convection has come from studying the Sun: about two million convective cells with typical sizes of around 2,000 kilometres across are present on the surface of the Sun—a phenomenon known as granulation. But on the surfaces of giant and supergiant stars there should be only a few large (several tens of thousands of times larger than those on the Sun) convective cells, owing to low surface gravity. Deriving the characteristic properties of convection (such as granule size and contrast) for the most evolved giant and supergiant stars is challenging because their photospheres are obscured by dust, which partially masks the convective patterns. These properties can be inferred from geometric model fitting, but this indirect method does not provide information about the physical origin of the convective cells. Here we report interferometric images of the surface of the evolved giant star π1 Gruis, of spectral type S5,7. Our images show a nearly circular, dust-free atmosphere, which is very compact and only weakly affected by molecular opacity. We find that the stellar surface has a complex convective pattern with an average intensity contrast of 12 per cent, which increases towards shorter wavelengths. We derive a characteristic horizontal granule size of about 1.2 × 1011 metres, which corresponds to 27 per cent of the diameter of the star. Our measurements fall along the scaling relations between granule size, effective temperature and surface gravity that are predicted by simulations of stellar surface convection.

doi: 10.1038/nature25001

An extracellular network of Arabidopsis leucine-rich repeat receptor kinases p.342

The cells of multicellular organisms receive extracellular signals using surface receptors. The extracellular domains (ECDs) of cell surface receptors function as interaction platforms, and as regulatory modules of receptor activation. Understanding how interactions between ECDs produce signal-competent receptor complexes is challenging because of their low biochemical tractability. In plants, the discovery of ECD interactions is complicated by the massive expansion of receptor families, which creates tremendous potential for changeover in receptor interactions. The largest of these families in Arabidopsis thaliana consists of 225 evolutionarily related leucine-rich repeat receptor kinases (LRR-RKs), which function in the sensing of microorganisms, cell expansion, stomata development and stem-cell maintenance. Although the principles that govern LRR-RK signalling activation are emerging, the systems-level organization of this family of proteins is unknown. Here, to address this, we investigated 40,000 potential ECD interactions using a sensitized high-throughput interaction assay, and produced an LRR-based cell surface interaction network (CSILRR) that consists of 567 interactions. To demonstrate the power of CSILRR for detecting biologically relevant interactions, we predicted and validated the functions of uncharacterized LRR-RKs in plant growth and immunity. In addition, we show that CSILRR operates as a unified regulatory network in which the LRR-RKs most crucial for its overall structure are required to prevent the aberrant signalling of receptors that are several network-steps away. Thus, plants have evolved LRR-RK networks to process extracellular signals into carefully balanced responses.

doi: 10.1038/nature25184