Volume 464 Issue 7285, 4 March 2010

International university rankings need to be improved — and interpreted more wisely.

General science meetings are good opportunities for researchers to broaden their horizons.

The week in science

Experts debate how much emergency-response planners should rely on tsunami forecasts.

Drones will measure ozone and aerosols in the atmosphere.

Systems for ranking the world's higher-education and research institutions are about to become more sophisticated, says Declan Butler.

Overfed lab animals make poor subjects for experiments.

Launching the European Research Council was a Herculean effort, says its outgoing president.

President takes first steps towards goal of disarmament.

The bold ambitions of one institute could make China the world leader in genome sequencing. David Cyranoski asks if its science will survive the industrial ramp-up.

Georgia's borders are guarded by some of the best radiation detectors available — so why are nuclear smugglers still slipping through? Sharon Weinberger reports.

Effective action on climate requires better politics, not better science, explains Daniel Sarewitz.

The US Congress should discourage efforts to advance the technology to make fuel for nuclear reactors, say Francis Slakey and Linda R. Cohen — the risks outweigh the benefits.

Paul Davies's latest book argues that the search for intelligent life beyond Earth should be expanded. Chris McKay considers why we should look closer to home — perhaps even in our DNA.

Joanna Cole has authored more than 100 science books for children, including the best-selling Magic School Bus series, the latest edition of which tackles the topic of climate change. In the last of our series of interviews with authors who write science books for different audiences, Cole reveals how clarity and colour can introduce even very young children to science.

Mosquitoes' odorant receptors help the insects to find humans and, inadvertently, to transmit malaria. The identification of the odorants that bind to these receptors opens up ways of reducing mosquito biting.

A neat mode of operation of the atomic force microscope has been used to probe the interface between mica and water. The results help to settle a long-standing debate about the nature of this interface.

Superconductivity has been discovered in the materials that form when alkali metals react with a solid hydrocarbon. This is the first new class of organic, high-temperature superconductor in a decade.

The cellular organelles we know as mitochondria are thought to have originated as symbiotic bacteria. Indeed, the two use common mechanisms to trigger innate immune responses to injury and infection, respectively.

Catastrophic breakage of brittle materials such as ceramics is usually triggered by the rapid spreading of cracks. Computer simulations have now cracked the three-dimensional details of this process.

A humble, gentle and visionary giant of molecular biology.

Local adaptations are often governed by several interacting genes scattered throughout the genome. Here a novel type of multi–locus genetic variation is described that has been maintained within a species over a vast period of time. A balanced unlinked gene network polymorphism is dissected that involves galactose utilization in a close relative of baker's yeast.

Deep metagenomic sequencing and characterization of the human gut microbiome from healthy and obese individuals, as well as those suffering from inflammatory bowel disease, provide the first insights into this gene set and how much of it is shared among individuals. The minimal gut metagenome as well as the minimal gut bacterial genome is also described.

Insect vectors of diseases locate their animal hosts through olfaction via largely unknown molecular processes. Here the 'empty neuron' system of genetically engineered Drosophila is used to assign specific odorants to the entire repertoire of olfactory receptors of the malaria vector Anopheles gambiae. The results illuminate ecological and neurobiological differences between mosquitoes and fruitflies and provide new potential molecular targets to boost the struggle against insect–borne diseases.

Current models indicate that the Milky Way's stellar halo was assembled from many smaller systems, and recent studies claimed that the true Galactic building blocks must have been vastly different from the surviving dwarfs. But the overall abundance pattern of elements in S1020549, the most iron-poor star in the Sculptor dwarf galaxies, is now found to follow that seen in low-metallicity halo stars, indicating that the systems destroyed to form the halo billions of years ago were not fundamentally different from the progenitors of present-day dwarfs.

The phenomenon of superconductivity continues to intrigue, and several new superconducting materials have been discovered in recent years — but in the case of organic superconductors, no new material system with a high superconducting transition temperature has been identified in the past decade. Now it has been shown that the introduction of potassium into crystals of organic molecule picene can yield superconductivity at temperatures as high as 18 K.

To integrate microchips with optical communications a photodetector is required to mediate the optical and electronic signals. Although germanium photodetectors are compatible with silicon their performance is impaired by poor intrinsic noise. Here the noise is reduced by nanometre engineering of optical and electrical fields to produce a compact and efficient photodetector.

The addition of shear orthogonal to the tension-loading plane of crack propagation generates an instability that results in three-dimensional helical crack propagation, atomically rough surfaces and a fracture pattern resembling a series of lance shapes. Here numerical simulations reveal a new law that governs crack propagation in space for materials subject to general stress conditions.

UCYN–A is a recently discovered nitrogen-fixing cyanobacterium with unusual metabolic features. The complete genome of this uncultivated organism is now presented, revealing a photofermentative metabolism and dependency on other organisms for essential compounds.

A new genus and species is described from fragmentary remains of a reptile from the mid–Triassic of Tanzania. The finding clarifies the relationships among the silesaurs. It is among the earliest known ornithodirans (dinosaurs plus pterosaurs), and demonstrates that silesaurs were not two-legged carnivores, as expected, but larger and more herbivorous. Furthermore, the find shows that we still know very little about the earliest stages of dinosaur and pterosaur evolution.

The organization of Hox clusters in several different reptiles is investigated, showing that the Hox clusters in squamates — lizards and snakes — have unexpectedly accumulated transposable elements, reflecting extensive genomic rearrangements of coding and non coding regulatory regions. Comparative expression analyses between two species showing different axial skeletons, the corn snake and the whiptail lizard, revealed major alterations in Hox13 and Hox10 expression features during snake somitogenesis, in line with the expansion of both caudal and thoracic regions.

Severe trauma can lead to death and sepsis in the absence of apparent infection. Here evidence shows that mitochondrial debris, released from damaged cells, is present in the circulation of seriously injured trauma patients. Such debris is shown to activate neutrophils via specific formyl peptide receptors, triggering systemic inflammation and end organ injury.

One of two papers showing the generation of haematopoietic stem cells (HSCs) from the ventral wall of the dorsal aorta in live zebrafish embryos. Here, combined fluorescent reporter transgenes, confocal time-lapse microscopy and flow cytometry identify and isolate the stepwise intermediates as aortic haemogenic endothelium transitions to nascent HSCs. HSCs generated from this haemogenic endothelium are the lineal founders of virtually all of the adult haematopoietic system.

One of two papers showing the generation of haematopoietic stem cells (HSCs) from the ventral wall of the dorsal aorta in live zebrafish embryos. Here, using imaging of live zebrafish, HSCs are shown to emerge directly from the aorta floor. This process does not involve cell division but movement of single endothelial cells out of the aorta ventral wall into the sub aortic space, where they transform into haematopoietic cells.

De novo emergence of phenotypically defined haematopoietic stem cells (Sca1⁺, c kit⁺, CD41⁺) directly from ventral aortic haemogenic endothelial cells is shown in mice. Although the study did not visualize live embryos, it instead developed a dissection procedure to visualize the deeply located aorta.

During fasting SIRT3 is induced in liver and brown adipose tissue. One of SIRT3's substrates is shown to be long–chain acyl co-enzyme A dehydrogenase (LCAD). Without SIRT3 LCAD becomes hyperacetylated, which diminishes its activity, and reduces fatty acid oxidation. Mice without SIRT3 have all the hallmarks of fatty acid oxidation disorders during fasting, including reduced ATP levels and intolerance to cold. Thus, acetylation is a novel regulatory mechanism for fatty acid oxidation.

Concerns about food shortages, land use, climate change and biodiversity have created a huge need for interdisciplinary researchers focused on agriculture. Virginia Gewin investigates the opportunities.

Different business models for difficult times.