Volume 576 Issue 7787, 19 December 2019

Climate strikes, marsquakes and gaming AIs are among the year’s top stories.

Picks include a quantum pioneer, a co-discoverer of Ebola and a bioethicist-turned-activist.

A black hole’s perilous edge, anti-poaching warriors, whisky webs and more.

Leading thinkers choose past works illuminating crucial issues today.

Scientists reflect on a year of civil unrest. Writing from Syria, Bolivia, Sudan, Iran, Chile, Ecuador, Lebanon, Venezuela, Hong Kong and Catalonia, correspondents tell of altered priorities, day-to-day challenges and hope in the dark times.

Highlights from News & Views published this year.

Understanding what happens in cities after sunset is crucial to global sustainable development, argues Michele Acuto.

Mitochondria, best known as the cell’s power plants, live a double life.

A bamboo craft built to resemble prehistoric boats proves unfit for a sea voyage.

Deaths decline at US nursing homes but rise in US hospice facilities.

Ultrasound pulses trigger an electrifying effect in samples of Achilles tendon, heart valve and more.

Stalagmites record thousands of years of northern Africa’s climate history.

Matriarch whales have a powerful effect on the lives of their grandchildren.

Astronomers detail the jarring journey of the MASCOT lander to the surface of an asteroid.

The latest science news, in brief.

Brexit certainty intensifies researchers’ concerns about international collaboration and access to European Union funds.

US$29-million investment aims to boost the country’s status as an international scientific powerhouse.

Analysis finds that the planet’s protective shield was in place by at least 3.7 billion years ago, as early life arose.

NASA’s Mars InSight lander has detected more than 300 quakes and traced some back to their source.

A pioneer in sustainable innovation explains why she has spent the past decade fighting the first lawsuit to force a government to act on global heating.

Four scientists reveal their key lessons from the publication process.

Powering through floods, exhaustion and tick bites is all in a day’s work for Jodi Rowley.

Immune cells called cytotoxic T cells can recognize and destroy cancer cells. The finding that stem-cell-like T cells exist in tumours, at niche sites that support these cells, could aid efforts to boost anticancer immune responses.

In 1994, an unconventional form of superconductivity was detected in strontium ruthenate. The discovery has shed light on the mechanism of unconventional superconductivity at high temperatures.

A double membrane protects certain bacteria from antibiotics, but compounds have now been generated that can overcome this obstacle, seemingly by targeting a crucial protein in the outer membrane.

A material that has electrically conducting surfaces has been found to show, when cooled, a type of magnetic ordering that reduces conduction at the surfaces. Such remarkable behaviour could have practical applications.

Enhancing antitumour immune responses has revolutionized cancer treatment, yet some hurdles impede this approach. The discovery of a way to boost the lifespan and function of antitumour immune cells removes a key obstacle.

Current barriers and limitations to HIV treatments are reviewed, and suggestions for future steps to achieve an effective curative intervention are discussed.

The ergodic hypothesis is used to produce a statistical solution to the chaotic non-hierarchical three-body problem.

An individual electron is used as a quantum sensor to realize atomic-scale magnetic resonance imaging.

An intrinsic antiferromagnetic topological insulator, MnBi₂Te₄, is theoretically predicted and then realized experimentally, with implications for the study of exotic quantum phenomena.

In theory, the anomalous quantum Hall effect is observed in edge channels of topological insulators when there is a magnetic energy gap at the Dirac point; this gap has now been observed by low-temperature photoelectron spectroscopy in Mn-doped Bi₂Te₃.

Theoretical modelling shows that elastic fluctuations can enable the tuning of metal-to-insulator transitions, potentially also explaining the dependence of the transition temperature on cation radius in perovskite transition-metal oxides.

Study of droplets containing nematic liquid crystal oligomers shows that a heterogeneous distribution of chain lengths plays a key part in driving reversible shape transformations with cooling and heating.

Nucleation experiments with water droplets containing differently sized graphene oxide nanosheets provide an experimental indication of the temperature-dependent size of the critical ice nucleus.

A rock art panel from Sulawesi—dated to at least 43.9 thousand years ago—represents the oldest currently known figurative art in the world, and provides evidence of early storytelling through narrative hunting scenes.

Frontal cortex neurons can be grouped into categorical response types corresponding to particular decision variables, such as reward size, decision confidence, or value, and individual variables may be encoded in distinct projection populations; this suggests that, like  neurons in sensory cortex, frontal neurons form a sparse and overcomplete representation of important variables in the environment.

A class of chimeric synthetic antibiotics that bind to lipopolysaccharide and BamA shows potent activity against multidrug-resistant Gram-negative bacteria, with the potential to address life-threatening infections.

Bacterial symbionts of animals may contain antibiotics that are particularly suitable for development into therapeutics; one such compound, darobactin, is active against important Gram-negative pathogens both in vitro and in animal models of infection.

The authors examine the immune cell infiltrates of human tumours and provide evidence for a population of CD8 T cells with stem-cell characteristics and proliferative capacity that reside in an antigen-presenting niche within tumours.

CRISPR–Cas9 mutagenesis screenings reveal that targeting REGNASE-1 leads to improved therapeutic efficacy of CD8⁺ T cells against mouse models of cancer, and identify BATF as a key target of REGNASE-1.

A whole-genome short interfering RNA screen identified vacuolar ATPase as a regulator of macropinocytosis induced by oncogenic RAS, a key determinant of tumour cell growth under nutrient-limiting conditions.

KRAS4A interacts directly with hexokinase 1 in a GTP-dependent manner at the outer mitochondrial membrane, leading to kinase activation and an increase in glucose uptake and glycolysis in tumour cells.

Single-cell mapping of chromatin accessibility, DNA methylation and RNA expression during gastrulation in mouse embryos shows characteristic epigenetic changes that accompany formation of the primary germ layers.

Partial structures are reported for Ca_v3.1 both on its own and in complex with a phase II drug candidate for seizure and neuropathic pain; this presents the overall architecture of T-type Ca²⁺ channels, insights into their gating and permeation mechanisms, and how they are modulated by small-molecule blockers.