Volume 517 Number 7533

Editorials

Reasons to be cheerful p.121

As two new fronts in the war on disease demonstrate, creativity remains a key weapon for scientists in the hunt for drugs.

doi: 10.1038/517121a

Listen up p.121

Human echolocation kicks off the Nature podcast’s new series on sound science

doi: 10.1038/517121b

News

News Features

The insurmountable gulf p.132

Twenty-four years after the conflict ended, scientists and veterans are still fighting for recognition of Gulf War illness.

doi: 10.1038/517132a

Pollution patrol p.136

Step aside, fitness trackers. The next wave of personal sensors is giving people the ability to monitor the air they breathe.

doi: 10.1038/517136a

News & Views

Carbon at the coastal interface p.148

The extent to which coastal-ocean regions act as a sink for carbon dioxide has been enigmatic. An estimate based on more than 3 million observations suggests a smaller sink than was thought, concentrated at high latitudes.

doi: 10.1038/nature14082

Enzymes surf the heat wave p.149

Molecular diffusion of some enzymes is enhanced when they catalyse reactions, but the reason for this was obscure. Dissipation of heat generated by catalysis through the protein is now thought to propel the molecules. See Letter p.227

doi: 10.1038/nature14079

Unburnable fossil-fuel reserves p.150

How much more of Earth's fossil fuels can we extract and burn in the short- to medium-term future and still avoid severe global warming? A model provides the answer, and shows where these 'unburnable' reserves are. See Letter p.187

doi: 10.1038/517150a

Resistance through repopulation p.152

Bladder-cancer cells have been found to release prostaglandin E2 when they are killed by chemotherapy. Paradoxically, this molecule stimulates the proliferation of surviving cancer stem cells, leading to tumour repopulation. See Letter p.209

doi: 10.1038/nature14075

Spin memories in for the long haul p.153

Spin systems have now been found that have lifetimes of up to six hours. They could be used to build quantum-communication networks and, if optical transmission fails, could even be shipped as a 'quantum memory stick'. See Letter p.177

doi: 10.1038/517153a

The versatile and plastic liver p.155

There is conflicting evidence about which cell type is responsible for liver regeneration following damage. It emerges that duct-like progenitor cells arise from hepatocytes after liver damage, a finding that reconciles previous data.

doi: 10.1038/517155a

A three-dimensional neural compass p.156

The discovery that the neural navigation system of the mammalian brain acts in three dimensions sheds light on how mammals orient themselves in complex environments. See Article p.159

doi: 10.1038/nature14076

Articles

Three-dimensional head-direction coding in the bat brain p.159

A study of freely moving bats provides new insights into how the brain encodes a three-dimensional neural compass; neurons were identified encoding the three Euler rotation angles of the head (azimuth, pitch, and roll) and recordings from these head-direction cells revealed a toroidal model of spatial orientation mapped out by cells tuned to two circular variables (azimuth × pitch).

doi: 10.1038/nature14031

Human gut Bacteroidetes can utilize yeast mannan through a selfish mechanism p.165

Mannan, a component of yeast cell walls, is shown to be a viable food source for Bacteroides thetaiotamicron, a dominant member of the gut microbiota, which catabolizes the mannan ‘selfishly’—countering the general assumption that multiple members of the gut microbiota take a role in, and benefit from, polysaccharide catabolism.

doi: 10.1038/nature13995

Letters

The temperature and chronology of heavy-element synthesis in low-mass stars p.174

Spectrographically obtained zirconium, niobium and technetium abundances in a sample of low-mass stars of type S are used to determine that, in these stars, heavy elements are synthesized by the slow-neutron-capture process at a temperature of less than about 250 million kelvin, and that the process began one million to three million years ago.

doi: 10.1038/nature14050

The geographical distribution of fossil fuels unused when limiting global warming to 2 °C p.187

Policy makers have generally agreed that the average global temperature rise caused by greenhouse gas emissions should not exceed 2 °C above the average global temperature of pre-industrial times. It has been estimated that to have at least a 50 per cent chance of keeping warming below 2 °C throughout the twenty-first century, the cumulative carbon emissions between 2011 and 2050 need to be limited to around 1,100 gigatonnes of carbon dioxide (Gt CO2). However, the greenhouse gas emissions contained in present estimates of global fossil fuel reserves are around three times higher than this, and so the unabated use of all current fossil fuel reserves is incompatible with a warming limit of 2 °C. Here we use a single integrated assessment model that contains estimates of the quantities, locations and nature of the world’s oil, gas and coal reserves and resources, and which is shown to be consistent with a wide variety of modelling approaches with different assumptions, to explore the implications of this emissions limit for fossil fuel production in different regions. Our results suggest that, globally, a third of oil reserves, half of gas reserves and over 80 per cent of current coal reserves should remain unused from 2010 to 2050 in order to meet the target of 2 °C. We show that development of resources in the Arctic and any increase in unconventional oil production are incommensurate with efforts to limit average global warming to 2 °C. Our results show that policy makers’ instincts to exploit rapidly and completely their territorial fossil fuels are, in aggregate, inconsistent with their commitments to this temperature limit. Implementation of this policy commitment would also render unnecessary continued substantial expenditure on fossil fuel exploration, because any new discoveries could not lead to increased aggregate production.

doi: 10.1038/nature14016

Blocking PGE2-induced tumour repopulation abrogates bladder cancer chemoresistance p.209

Using human bladder cancer xenograft models, a new mechanism involving an active proliferative response of cancer stem cells to chemotherapy-induced damage is shown, driven by prostaglandin E2 (PGE2) release in a manner similar to PGE2-induced wound repair; pharmacological inhibition of the PGE2/COX2 axis by celecoxib attenuates chemoresistance, suggesting a possible adjunctive therapy for bladder carcinomas.

doi: 10.1038/nature14034

T–B-cell entanglement and ICOSL-driven feed-forward regulation of germinal centre reaction p.214

Interactions between T and B cells in the germinal centre are brief but involve extensive cell-surface contact in an entangled mode; ICOSL promotes T–B entanglement and B-cell acquisition of CD40L, which drives B cells to upregulate ICOSL, thus forming an intercellular feed-forward loop that is required for efficient positive selection and development of the bone marrow plasma cell compartment.

doi: 10.1038/nature13803

The heat released during catalytic turnover enhances the diffusion of an enzyme p.227

It has been traditionally assumed that the heat released during a single enzymatic catalytic event does not perturb the enzyme in any way; however, here single-molecule fluorescence correlation spectroscopy is used to show that, for enzymes that catalyse chemical reactions with large reaction enthalpies, the heat released at the protein's active site during catalysis transiently displaces the protein's centre-of-mass, essentially giving rise to a recoil effect that propels the enzyme.

doi: 10.1038/nature14043