Volume 510 Number 7504

Editorials

Good practice p.187

Standardized procedures and analyses should help to get stem-cell therapies to the clinic.

doi: 10.1038/510187b

A growing problem p.187

Without careful stewardship, genetically engineered crops will do little to stop the spread of herbicide-resistant weeds.

doi: 10.1038/510187a

Open goal p.188

International researchers can help to improve the scientific enterprise in South America.

doi: 10.1038/510188a

News

News Features

Stars of South American science p.201

Growing resources for research and development are creating opportunities across the continent, but many countries still struggle to build their programmes.

doi: 10.1038/510201a

News & Views

Materials science: Diamond gets harder p.220

Composite materials that incorporate diamond are among the hardest in the world, but fail under extreme conditions. A nanostructured form of diamond, made from onion-like carbon precursors, might overcome this problem. See Letter p.250

doi: 10.1038/510220a

Plant biology: Pass the ammunition p.221

Tomato plants that have been damaged by herbivorous insects emit airborne chemicals that warn neighbours of an impending attack. It emerges that the receiving plants transform these signals into defensive weapons.

doi: 10.1038/510221a

Immunology: When lymphocytes run out of steam p.222

The finding that absence of the enzyme CTPS1 underlies a form of human immunodeficiency highlights the role of metabolism in immune responses and suggests avenues for treating diseases such as leukaemia. See Letter p.288

doi: 10.1038/nature13346

Particle physics: The hunt for Majorana neutrinos hots up p.224

Finding that neutrinos are their own antiparticles would revolutionize particle physics. A high-sensitivity technique accelerates the search for the nuclear-decay process that would enable such a discovery. See Article p.229

doi: 10.1038/nature13501

Cancer biology: Enzyme meets a surprise target p.225

An enzyme previously implicated in gene regulation has now been found to have a role in cancer progression, potentiating an intracellular signalling pathway that is driven by a mutated K-Ras protein. See Letter p.283

doi: 10.1038/nature13343

Gene therapy: Repair and replace p.226

One approach to treating inherited diseases is repairing the defective genes, but this has proved challenging in stem cells. An optimized protocol has now been developed that allows gene repair in blood-cell precursors. See Article p.235

doi: 10.1038/nature13344

Articles

Search for Majorana neutrinos with the first two years of EXO-200 data p.229

The EXO-200 Collaboration Neutrinos are known to have mass, in contradiction to the predictions of the standard model, and one explanation of this mass is that they are Majorana fermions; this conjecture could be proved by observation of the neutrinoless double-β decay process, but new experiments with 136Xe find no statistically significant evidence for this process.

doi: 10.1038/nature13432

Homologue engagement controls meiotic DNA break number and distribution p.241

Drew Thacker, Neeman Mohibullah, Xuan Zhu & Scott Keeney DNA double-stranded breaks (DSBs) are shown to form in greater numbers in yeast cells lacking ZMM proteins, which are traditionally regarded as acting strictly downstream of DSB formation; these findings shed light on how cells balance the beneficial and deleterious outcomes of DSB formation.

doi: 10.1038/nature13120

Letters

Two γ-ray bursts from dusty regions with little molecular gas p.247

Emission spectra from the host galaxies of two γ-ray bursts reveal that the regions where the bursts occur are rich in dust but not in molecular gas, which is unexpected because γ-ray bursts are associated with the explosions of massive stars that require molecular gas as fuel.

doi: 10.1038/nature13325

Emergence of reproducible spatiotemporal activity during motor learning p.263

Inhibitory neuron activity is found to be relatively stable during motor learning whereas excitatory neuron activity is much more dynamic — the results indicate that a large number of neurons exhibit activity changes early on during motor learning, but this population is refined with subsequent practice.

doi: 10.1038/nature13235

The unfolded protein response governs integrity of the haematopoietic stem-cell pool during stress p.268

Molecular, pharmacological and functional data show that haematopoietic stem cells (HSCs) are predisposed to ER-stress-mediated apoptosis compared to closely related progenitors; a framework for understanding how stress signalling is coordinated within the hematopoietic hierarchy and integrated with stemness is provided, and may have implications for the improvement of clinical transplantation of HSCs.

doi: 10.1038/nature13228

SMYD3 links lysine methylation of MAP3K2 to Ras-driven cancer p.283

SMYD3 is a methyltransferase overexpressed in several human tumours; here methylation of the MAP3K2 kinase by SMYD3 is shown to be critical for Ras-induced tumour development in mouse models and human tumour cells, showing an unexpected role for methylation in a kinase signalling pathway and revealing a candidate therapeutic target.

doi: 10.1038/nature13320

Quantitative flux analysis reveals folate-dependent NADPH production p.298

A metabolomics quantification of NADPH production and consumption fluxes in proliferating mammalian cells reveals that, in addition to canonical pathways such as the oxidative pentose phosphate pathway, NADPH can also be produced by a folate metabolism pathway, a discovery providing new insights into the metabolism of cell growth.

doi: 10.1038/nature13236