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Nuclear ambition p1103

The US weapons labs need to develop a twenty-first-century vision of deterrence — one that does not include making new bombs.


The weight of evidence p1103

Better chemical-control legislation is a good start, but scientific reform should parallel legal reform.


Time for libel-law reform p1104

Simon Singh's recent libel result is a victory for science, but the real fight lies ahead.



Research Highlights

Planetary science: Moon grab p1106


Neuroscience: Relief from pain p1106


Biomaterials: Electronics on the brain p1106


Cultural evolution: High fidelity p1106


Cell biology: Toxin tackle p1106


Chemistry: Plumbing carbon rings p1106


Cancer biology: Cells combat chemo p1107


Neuroscience: Sharpening social skills p1107


Climate change: Fewer, taller, fiercer p1107


Immunology: Inflammatory good guys p1107



Journal Club

Journal club p1107

Kevin Mitchell




News briefing: 22 April 2010 p1108

The week in science


A shot in the arm for cancer vaccines? p1110

Researchers anxiously await a decision by US regulators on a controversial cancer therapy.

Heidi Ledford


No gain from brain training p1111

Computerized mental workouts don't boost mental skills, study claims.

Alla Katsnelson


Portrait of a year-old pandemic p1112

'Swine flu' isn't over yet, but it already holds lessons for the future.

Declan Butler


Undersea project delivers data flood p1115

Sea-floor observatory in the Pacific Ocean to provide terabytes of data.

Nicola Jones


Crucial data on REACH not disclosed p1116

Disagreement flares up over the number of animals required to implement Europe's chemical-safety law.

Natasha Gilbert



News Features

Environmental science: New life for the Dead Sea? p1118

A conduit from the Red Sea could restore the disappearing Dead Sea and slake the region's thirst. But such a massive engineering project could have untold effects, reports Josie Glausiusz.


Toxicology: The big test for bisphenol A p1122

After years of wrangling over the chemical's toxicity, researchers are charting a new way forwards. Brendan Borrell investigates how the debate has reshaped environmental-health studies.




Climate policy: role of scientists in public advocacy p1125

Stephen H. Schneider


Climate policy: dissent over moral as well as factual issues p1125

Gregor Betz


What users really want to know from university ratings p1125

Jimmy J. Zhuang, Annie X. Wang & Joyce Y. Zhang


African students value the results of studying in China p1125

Kenneth King


Actions speak louder than words to prevent language extinctions p1125

Yoshina Gautam & Aashish Jha




Copenhagen Accord pledges are paltry p1126

Current national emissions targets can't limit global warming to 2 °C, calculate Joeri Rogelj, Malte Meinshausen and colleagues — they might even lock the world into exceeding 3 °C warming.

Joeri Rogelj, Julia Nabel, Claudine Chen, William Hare, Kathleen Markmann, Malte Meinshausen, Michiel Schaeffer, Kirsten Macey & Niklas Höhne



Books and Arts

Building life from the bottom up p1129

Engineering biological systems and organisms is a costly team effort and may be incompatible with an open-source regulatory environment, finds Michael A. Goldman.

Michael A. Goldman reviews Biology is Technology: The Promise, Peril, and New Business of Engineering Life by Robert H. Carlson


Why twins age differently p1130

Michael Sargent reviews Epigenetics of Aging Edited by Trygve O. Tollefsbol


Where the wilderness line blurs p1131

Emma Marris reviews Living Through the End of Nature: The Future of American Environmentalism by Paul Wapner



News and Views

Diabetes forum: Extreme makeover of pancreatic α-cells p1132

Most insulin-secreting pancreatic β-cells are irreplaceably lost in type 1 diabetes. In a mouse model, pancreatic α-cells seem to sacrifice their identity to replenish the low stock of β-cells1. Two experts discuss what this means for understanding the basic cell biology involved and its relevance to treating diabetes.

Kenneth S. Zaret & Morris F. White


See also: Editor's summary | Article by Thorel et al.

Quantum measurement: A condensate's main squeeze p1133

Entanglement between particles permits the quantum uncertainty in one variable to be reduced at the cost of increasing that in another. Condensates are an ideal system in which this technique can be studied.

Charles A. Sackett


See also: Editor's summary | Letter by Gross et al. | Letter by Riedel et al.

Neuroscience: Signals far and away p1134

The neocortex of the mammalian brain mediates functions such as sensory perception and ultimately consciousness and language. The spread of local signals across large distances in this brain region has now been clarified.

Dirk Feldmeyer


See also: Editor's summary | Article by Adesnik & Scanziani

Chemistry: Not just any old anion p1136

Unlike its neighbours on the right-hand side of the periodic table, boron barely forms an anion. A new trick has been established that allows it to do so, enabling a highly unusual complex to be prepared.

Kyoko Nozaki


Materials science: A cloak of liquidity p1137

Droplets of a liquid alloy on a silicon surface can rearrange the surface atoms so that they mimic the short-range ordering of atoms in the alloy. Remarkably, this effect inhibits freezing of the droplets.

A. Lindsay Greer


See also: Editor's summary | Letter by Schülli et al.

50 & 100 years ago p1138


Infectious disease: Listeria does it again p1138

Proteins are synthesized by ribosomes, and then commonly undergo further modifications. A new example of how these host-cell processes can e subverted by a pathogenic bacterium has come to light.

Julian I. Rood


See also: Editor's summary | Letter by Ribet et al.

Q&A: Animal behaviour: Magnetic-field perception p1140

The ability to perceive Earth's magnetic field, which at one time was dismissed as a physical impossibility, is now known to exist in diverse animals. The receptors for the magnetic sense remain elusive. But it seems that at least two underlying mechanisms exist — sometimes in the same organism.

Kenneth J. Lohmann




Generation of a novel wing colour pattern by the Wingless morphogen p1143

Here, the generation and evolution of the complex spotted wing pattern of Drosophila guttifera are investigated. The findings show that wing spots are induced by the Wingless morphogen, and that the elaborate spot pattern evolved from simpler schemes by co-option of Wingless expression at new sites. This type of process is likely to occur in other animals, too.

Thomas Werner, Shigeyuki Koshikawa, Thomas M. Williams & Sean B. Carroll


See also: Editor's summary

Conversion of adult pancreatic α-cells to β-cells after extreme β-cell loss p1149

In the pancreas, insulin-producing β-cells are long-lived and generally replicate seldom. They can do so, however, after increased metabolic demand or after injury. Here, a new transgenic model is developed in which β-cells are nearly completely ablated in mice. If given insulin, these mice survive, and grow new β-cells. Lineage-tracing shows that these new β-cells come from α-cells, revealing a previously disregarded degree of pancreatic cell plasticity.

Fabrizio Thorel, Virginie Népote, Isabelle Avril, Kenji Kohno, Renaud Desgraz, Simona Chera & Pedro L. Herrera


See also: Editor's summary | News and Views by Zaret & White

Lateral competition for cortical space by layer-specific horizontal circuits p1155

A common anatomical feature of the sensory cortex in many species is that neurons with similar features cluster into vertically orientated domains spanning all layers of the cortex. Moreover, neurons in one domain modulate neurons in neighbouring domains through horizontal connections. A combination of techniques has now been used to show that such horizontal projections suppress layers of cortex devoted to processing inputs, but facilitate layers devoted to outputs.

Hillel Adesnik & Massimo Scanziani


See also: Editor's summary | News and Views by Feldmeyer



Possible thermochemical disequilibrium in the atmosphere of the exoplanet GJ 436b p1161

Here, the atmosphere of the extrasolar planet GJ 436b is studied during its 'secondary eclipse'. The findings reveal the presence of some H2O and traces of CO2. The best-fit compositional models contain a high CO abundance and a substantial methane deficiency relative to thermochemical equilibrium models for the predicted hydrogen-dominated atmosphere. Disequilibrium processes such as vertical mixing and polymerization of methane may be required to explain this small methane-to-CO ratio.

Kevin B. Stevenson, Joseph Harrington, Sarah Nymeyer, Nikku Madhusudhan, Sara Seager, William C. Bowman, Ryan A. Hardy, Drake Deming, Emily Rauscher & Nate B. Lust


See also: Editor's summary

Nonlinear atom interferometer surpasses classical precision limit p1165

The precision of interferometers — used in metrology and in the state-of-the-art time standard — is generally limited by classical statistics. Here it is shown that the classical precision limit can be beaten by using nonlinear atom interferometry with Bose–Einstein condensates.

C. Gross, T. Zibold, E. Nicklas, J. Estève & M. K. Oberthaler


See also: Editor's summary | News and Views by Sackett

Atom-chip-based generation of entanglement for quantum metrology p1170

Atom chips provide a versatile quantum laboratory for experiments with ultracold atomic gases, but techniques to control atomic interactions and to generate entanglement have been unavailable so far. Here, the experimental generation of multi-particle entanglement on an atom chip is described. The technique is used to produce spin-squeezed states of a two-component Bose–Einstein condensate, which should be useful for quantum metrology.

Max F. Riedel, Pascal Böhi, Yun Li, Theodor W. Hänsch, Alice Sinatra & Philipp Treutlein


See also: Editor's summary | News and Views by Sackett

Substrate-enhanced supercooling in AuSi eutectic droplets p1174

Supercooling is a phenomenon by which a liquid remains in its fluid phase well below its melting point. Supercooling can be inhibited by the presence of a solid surface, whereby crystalline surfaces cause adjacent atoms in the liquid to become ordered, inducing crystal nucleation of the melt. Here it is shown that a particular surface ordering of gold atoms on top of a silicon substrate can stabilize the liquid phase of a gold-silicon eutectic droplet, and thus enhance supercooling.

T. U. Schülli, R. Daudin, G. Renaud, A. Vaysset, O. Geaymond & A. Pasturel


See also: Editor's summary | News and Views by Greer

Stoichiometric control of organic carbon–nitrate relationships from soils to the sea p1178

The accumulation of nitrate in freshwater and coastal marine ecosystems is one of the consequences of the worldwide production of artificial fertilizers. Here it is shown that nitrate accumulation in ecosystems shows consistent and negative nonlinear correlations with organic carbon availability, along a continuum from soils, through freshwater systems and coastal margins, to the open ocean. This pattern can be explained by carbon:nitrate ratios, which influence nitrate accumulation by regulating microbial processes.

Philip G. Taylor & Alan R. Townsend


See also: Editor's summary

Learning-related fine-scale specificity imaged in motor cortex circuits of behaving mice p1182

It is generally accepted that specific neuronal circuits in the brain's cortex drive behavioural execution, but the relationship between the performance of a task and the function of a circuit is unknown. Here, this problem was tackled by using a technique that allows many neurons within the same circuit to be monitored simultaneously. The findings indicate that enhanced correlated activity in specific ensembles of neurons can identify and encode specific behavioural responses while a task is learned.

Takaki Komiyama, Takashi R. Sato, Daniel H. O’Connor, Ying-Xin Zhang, Daniel Huber, Bryan M. Hooks, Mariano Gabitto & Karel Svoboda


See also: Editor's summary

Genetic analysis of variation in transcription factor binding in yeast p1187

Variation in the regulation of gene transcription between individuals is thought to be a major cause of phenotypic diversity. Here, individual differences in the binding of transcription-factor proteins are studied. A well-known transcription factor in the yeast pheromone pathway is used as an example, and the underlying genetic loci responsible for variation in its binding are mapped. The study reveals new insights into the mechanisms of gene regulation, and new regulators of the yeast pheromone pathway.

Wei Zheng, Hongyu Zhao, Eugenio Mancera, Lars M. Steinmetz & Michael Snyder


See also: Editor's summary

Listeria monocytogenes impairs SUMOylation for efficient infection p1192

SUMOylation is a post-translational protein modification that affects many eukaryotic cellular processes. It is shown here that cellular infection with Listeria monocytogenes induces degradation of one of the essential SUMOylation enzymes, Ubc9, through a mechanism that involves a bacterial toxin, listeriolysin O. This effect on SUMOylation may support efficient infection by Listeria.

David Ribet, Mélanie Hamon, Edith Gouin, Marie-Anne Nahori, Francis Impens, Hélène Neyret-Kahn, Kris Gevaert, Joël Vandekerckhove, Anne Dejean & Pascale Cossart


See also: Editor's summary | News and Views by Rood

MicroRNA-mediated integration of haemodynamics and Vegf signalling during angiogenesis p1196

During embryonic development, blood vessels remodel in response to blood flow. Here, a genetic pathway is described through which this mechanosensory stimulus is integrated with early developmental signals to remodel vessels of the aortic arch in zebrafish. It is found that the flow-induced transcription factor klf2a is required to induce the expression of an endothelial-specific microRNA, activating signalling through the growth factor Vegf.

Stefania Nicoli, Clive Standley, Paul Walker, Adam Hurlstone, Kevin E. Fogarty & Nathan D. Lawson


See also: Editor's summary

Caspase activation precedes and leads to tangles p1201

Fibrillar deposits of tau protein (neurofibrillary tangles) are thought to cause neuronal death in patients with Alzheimer's disease, and tau-related frontotemporal dementia. Here, however, the opposite has been found: the activation of executioner caspase enzymes occurs first, preceding tangle formation by hours to days. Tangle-bearing neurons seem to be long-lived, indicating that tangles might be 'off pathway' to acute neuronal death.

Alix de Calignon, Leora M. Fox, Rose Pitstick, George A. Carlson, Brian J. Bacskai, Tara L. Spires-Jones & Bradley T. Hyman


See also: Editor's summary

Crystal structure of the FTO protein reveals basis for its substrate specificity p1205

The fat mass and obesity-associated (FTO) gene has been associated with increased body weight. The FTO protein has DNA/RNA demethylase activity. Here, the crystal structure of human FTO in complex with the mononucleotide 3-methylthymidine is presented. The structure provides a basis for understanding the substrate specificity of FTO, and should serve as a foundation for the design of FTO inhibitors.

Zhifu Han, Tianhui Niu, Junbiao Chang, Xiaoguang Lei, Mingyan Zhao, Qiang Wang, Wei Cheng, Jinjing Wang, Yi Feng & Jijie Chai


See also: Editor's summary

Isolation of the elusive supercomplex that drives cyclic electron flow in photosynthesis p1210

During photosynthesis, light energy is used by photosystems I and II to establish electron flow, which ultimately results in the production of ATP and NADPH. Two modes of electron flow exist, a linear electron flow and a cyclic electron flow (CEF). The latter pathway generates more ATP, but its molecular components have been elusive. Here, a combination of biochemical and spectroscopic techniques has been used to identify the supercomplex that drives CEF in the green alga Chlamydomonas reinhardtii.

Masakazu Iwai, Kenji Takizawa, Ryutaro Tokutsu, Akira Okamuro, Yuichiro Takahashi & Jun Minagawa


See also: Editor's summary

Ku is a 5′-dRP/AP lyase that excises nucleotide damage near broken ends p1214

Most agents that generate breaks in DNA leave 'dirty ends' that cannot be joined immediately; instead, intervening steps are required to restore the integrity of nucleotides at the break. Here it is shown that the non-homologous end joining pathway requires a 5′-dRP/AP lyase activity to remove abasic sites at double-strand breaks. Surprisingly, this activity is catalysed by the Ku70 protein, which, together with its partner Ku86, had been thought only to recognize broken DNA ends and to recruit other factors that process ends.

Steven A. Roberts, Natasha Strande, Martin D. Burkhalter, Christina Strom, Jody M. Havener, Paul Hasty & Dale A. Ramsden


See also: Editor's summary

Super-resolution biomolecular crystallography with low-resolution data p1218

X-ray crystallography has become the most common way for structural biologists to obtain the three-dimensional structures of proteins and protein complexes. However, crystals of large macromolecular complexes often diffract only weakly (yielding a resolution worse than 4 Å), so new methods that work at such low resolution are needed. Here a new method is described by which to obtain higher-quality electron density maps and more accurate molecular models of weakly diffracting crystals.

Gunnar F. Schröder, Michael Levitt & Axel T. Brunger


See also: Editor's summary


Technology Feature

RNA interference: Homing in on delivery p1225

The scientific community now seems convinced that small RNAs will become therapies, if new tools can help these large molecules to make it safely into cells. Monya Baker reports.

Monya Baker


RNA interference: From tools to therapies p1225


RNA interference: MicroRNAs as biomarkers p1227


RNA interference: Table of suppliers p1229





Science outreach scheme ramps up p1233

More than 2,500 US scientists are participating in new initiative.

Karen Kaplan



The junior senior supervisor p1233

Mentoring students as a young researcher has its own particular challenges, suggests Fabio Paglieri.

Fabio Paglieri


Careers and Recruitment

Making a switch p1234

When inspiration strikes or desperation sets in, a bold few risk career suicide and move to new fields. Bryn Nelson reports on what it takes.

Bryn Nelson




Corrective action p1238

Accidents will happen.

John Gilbey


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