Volume 533 Number 7604

Editorials

Reality check on reproducibility p.437

A survey of Nature readers revealed a high level of concern about the problem of irreproducible results. Researchers, funders and journals need to work together to make research more reliable.

doi: 10.1038/533437a

Source material p.437

Geneticists and historians need to work together on using DNA to explore the past.

doi: 10.1038/533437b

Crunch time p.438

Overtime pay for postdoctoral scientists is welcome — but could mean fewer positions.

doi: 10.1038/533438a

News

News Features

The secret history of ancient toilets p.456

By scouring the remains of early loos and sewers, archaeologists are finding clues to what life was like in the Roman world and in other civilizations.

doi: 10.1038/533456a

News & Views

Choreography of protein synthesis p.472

Both nuclear genes and genes in organelles called mitochondria are involved in the assembly of the cellular energy-producing machinery. RNA-translation programs that coordinate the two systems have now been identified. See Article p.499

doi: 10.1038/nature18436

How black holes restrain old galaxies p.473

Supermassive black holes are thought to keep star formation under control by ejecting or stirring gas in galaxies. Observations of an old galaxy reveal a potential mechanism for how this process occurs. See Letter p.504

doi: 10.1038/533473a

Killer enzymes tethered p.474

Caspase enzymes promote cell death, but are also involved in sperm development in fruit flies. The discovery that, in sperm, caspase activation is restricted to the surface of organelles called mitochondria sheds light on this unusual role.

doi: 10.1038/nature18439

Ketamine steps out of the darkness p.477

The way in which ketamine exerts its antidepressant effects has been perplexing. Evidence that a metabolite of the drug is responsible, and acts on a different target from ketamine, might be the key to an answer. See Article p.481

doi: 10.1038/nature17897

Unexpected player in particle formation p.478

Three studies find that a family of organic compounds affects the formation and initial growth of atmospheric aerosol particles in clean air — with implications for our knowledge of the climate effects of aerosols. See Letters p.521 & 527

doi: 10.1038/533478a

Articles

NMDAR inhibition-independent antidepressant actions of ketamine metabolites p.481

The metabolism of ketamine to (2S,6S;2R,6R)-hydroxynorketamine (HNK) is essential for its antidepressant effects, and the (2R,6R)-HNK enantiomer lacks ketamine-related side effects but exerts rapid and sustained antidepressant actions in mice; these antidepressant effects are independent of NMDAR inhibition but require AMPAR activity.

doi: 10.1038/nature17998

Carcinoma–astrocyte gap junctions promote brain metastasis by cGAMP transfer p.493

A heterotypic cell interaction between astrocytes and tumour cells colonizing the brain is discovered; by establishing gap junctions, tumour cells trigger the activation of innate immune response signalling in astrocytes, which results in the secretion of factors that support growth and chemoresistance in brain metastatic cells.

doi: 10.1038/nature18268

Letters

A resonant chain of four transiting, sub-Neptune planets p.509

Transit timing variations of the four-planet system Kepler-223 are used to compute the long-term stability of the system, which has a chain of resonances; the results suggest that inward planetary migration, rather than in situ assembly, is responsible for the formation of some close-in sub-Neptune systems.

doi: 10.1038/nature17445

Ion-induced nucleation of pure biogenic particles OPEN p.521

Aerosol particles can form in the atmosphere by nucleation of highly oxidized biogenic vapours in the absence of sulfuric acid, with ions from Galactic cosmic rays increasing the nucleation rate by one to two orders of magnitude compared with neutral nucleation.

doi: 10.1038/nature17953

The role of low-volatility organic compounds in initial particle growth in the atmosphere OPEN p.527

The growth of nucleated organic particles has been investigated in controlled laboratory experiments under atmospheric conditions; initial growth is driven by organic vapours of extremely low volatility, and accelerated by more abundant vapours of slightly higher volatility, leading to markedly different modelled concentrations of atmospheric cloud condensation nuclei when this growth mechanism is taken into account.

doi: 10.1038/nature18271

Competitive growth in a cooperative mammal p.532

In wild Kalahari meerkats (Suricata suricatta), subordinates of both sexes respond to experimentally induced increases in the growth of same-sex rivals by raising their own growth rate and food intake.

doi: 10.1038/nature17986

How sexual selection can drive the evolution of costly sperm ornamentation p.535

The ‘big-sperm paradox’, the observed production of few, gigantic sperm by some fruit flies (seemingly at odds with fundamental theory addressing how sexual selection works) is shown to be a result of co-evolution driven by genetic and functional relationships between sperm length, design of the female reproductive tract and features of the mating system.

doi: 10.1038/nature18005