Review, News & Views, Perspectives, Hypotheses and Analyses in 2013

The discovery that schistosomes possess adult stem cells could explain the long-term persistence of these parasitic worms in humans. Targeting a protein produced by the cells might damage schistosome defences. See Letter p.476

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.

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

An analysis reveals the huge impact of human activity on the nitrogen cycle in China. With global use of Earth's resources rising per head, the findings call for a re-evaluation of the consumption patterns of developed societies. See Letter p.459

A bacterium and a fungus both use gene sequences that fail to optimize the production of circadian-clock proteins. Two studies reveal different reasons for the advantages of producing less protein. See Letters p.111 & p.116

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

A boron complex catalyses the addition of allyl groups — hydrocarbon motifs — to 'activated imines' in a relay-like process, generating synthetically useful compounds as single mirror-image isomers. See Letter p.216

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

When massive stars die as supernovae, these explosions can be seen out to the 'edge of the Universe'. But the stars' nature is often unclear. New observations provide insight into the life of one such star before it exploded. See Letter p.65

A detailed geological analysis of a ridge in the Indian Ocean suggests that compositional variations in Earth's mantle have a surprisingly crucial role in the uplift of a bathymetric bulge along the ridge. See Article p.195

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

Unusual strains of the pathogen Candida albicans have been found that contain a single set of chromosomes. Formation of such haploid strains weeds out damaged copies of genes to promote evolution in the human body. See Article p.55

Breakdown of dissolved organic nitrogen in the ocean had been thought to be the preserve of microbes at the surface. The discovery that these microbes are not up to the task calls for a reassessment of the biogeochemistry of this nitrogen pool.

To thwart the antimicrobial responses of their hosts, pathogens have evolved diverse mechanisms, including autophagy. Knowledge of such mechanisms has now led to a pro-autophagy peptide that may be of therapeutic value. See Article p.201

Physicists have puzzled over a hidden electronic order in a uranium-based material for decades. A new theory attributes it to not just a single but a double breaking of time-reversal symmetry. See Article p.621

By harnessing the way charge carriers move in a magnetic field, computing blocks based on semiconductor junctions have been made that are reconfigurable and can be interconnected to perform complex logic functions. See Letter p.72

Salt is important in health and disease, yet how mammals sense it is not completely clear. Evidence in worms suggests that TMC proteins, which are implicated in human hearing, are salt receptors involved in taste. See Letter p.95

The Sun's magnetic activity varies cyclically over a period of about 11 years. An analysis of a new, temporally extended proxy record of this activity hints at a possible planetary influence on the amplitude of the cycle.