Volume 494 Number 7437

Editorials

Eyes and ears p.281

Two explosions last week demonstrated the importance of global monitoring.

doi: 10.1038/494281b

Vital statistics p.281

That robust data are not collected on births, deaths and causes of death is a scandal. A new drive and greater investment are needed to grow the field of health metrics.

doi: 10.1038/494281a

Net gains p.282

Estimating the scale of the problem may allow us to arrest dangerous levels of overfishing.

doi: 10.1038/494282a

News

News Features

Green cement: Concrete Solutions p.300

Cement manufacturing is a major source of greenhouse gases. But cutting emissions means mastering one of the most complex materials known.

doi: 10.1038/494300a

News & Views

Palaeoanthropology: Of humans, dogs and tiny tools p.316

Genomic data hint at the possibility of human migration from India to Australia 4,230 years ago. However, the inference that these humans took along their dogs and tools is difficult to reconcile with previous reports.

doi: 10.1038/494316a

Ageing: Stem cells on a stress-busting diet p.317

Knowing how an organism's tissues handle stress throughout life is key to understanding ageing and disease. Stems cells of the blood system seem to tackle metabolic stress by means of a process called autophagy. See Article p.323

doi: 10.1038/nature11948

Climate science: Global warming and tropical carbon p.319

An innovative use of measurements of atmospheric carbon dioxide constrains the possible range of carbon–cycle responses to climate change during the twenty-first century, lowering expectations of tropical-forest dieback. See Letter p.341

doi: 10.1038/nature11949

Microbial oceanography: Killers of the winners p.320

Viruses that infect the SAR11 group of oceanic bacteria have finally been found and sequenced. Because SAR11 is ubiquitous, these viruses may be the most abundant in the oceans — and perhaps in the entire biosphere. See Letter p.357

doi: 10.1038/nature11951

Infection biology: Cheats never prosper p.321

Fast-growing 'defector mutants' can threaten the success of a bacterial infection. But one bacterial species prevails over these cheats by forming a subpopulation that has shut down expression of virulence genes. See Letter p.353

doi: 10.1038/494321a

Article

FOXO3A directs a protective autophagy program in haematopoietic stem cells p.323

Blood production is ensured by rare, self-renewing haematopoietic stem cells (HSCs). How HSCs accommodate the diverse cellular stresses associated with their life-long activity remains elusive. Here we identify autophagy as an essential mechanism protecting HSCs from metabolic stress. We show that mouse HSCs, in contrast to their short-lived myeloid progeny, robustly induce autophagy after ex vivo cytokine withdrawal and in vivo calorie restriction. We demonstrate that FOXO3A is critical to maintain a gene expression program that poises HSCs for rapid induction of autophagy upon starvation. Notably, we find that old HSCs retain an intact FOXO3A-driven pro-autophagy gene program, and that ongoing autophagy is needed to mitigate an energy crisis and allow their survival. Our results demonstrate that autophagy is essential for the life-long maintenance of the HSC compartment and for supporting an old, failing blood system.

doi: 10.1038/nature11895

Letters

Generation of electron Airy beams p.331

The diffraction of electrons through a nanoscale hologram that imprints a certain phase modulation on the electrons’ wavefunction produces a non-spreading electron Airy beam that follows a parabolic trajectory and can reconstruct its original shape after passing an obstacle.

doi: 10.1038/nature11840

Ecosystem resilience despite large-scale altered hydroclimatic conditions p.349

The resilience of a global sample of ecosystems to an increase in drought conditions is assessed, comparing data from the early twenty-first with the late twentieth century; results indicate a cross-ecosystem capacity for tolerating low precipitation and responding to high precipitation during recent warm drought and yet suggest a threshold to resilience with prolonged warm drought.

doi: 10.1038/nature11836

Abundant SAR11 viruses in the ocean p.357

Viruses are isolated from the SAR11 bacterial clade, the most abundant group of bacteria in the ocean, that were thought to be resistant to viral infection; because of the essential role of SAR11 in carbon cycling these viruses are also an important factor in biogeochemical cycling.

doi: 10.1038/nature11921

APOBEC3B is an enzymatic source of mutation in breast cancer p.366

The DNA cytosine deaminase APOBEC3B is shown to be overexpressed and highly active in most breast cancers; deamination by APOBEC3B could serve as an endogenous, continual source of DNA damage leading to mutations, including C-to-T transitions and other aberrations seen in many breast tumours.

doi: 10.1038/nature11881