Volume 484 Issue 7395, 26 April 2012

A planned commercial trip to the space station shows a future direction for NASA.

The use of leeches is making a comeback, and not just in medicine.

The first private-sector flight to the International Space Station will open up myriad opportunities for science, says Alan Stern.

The week in science: Roche drops pursuit of Illumina; UN ecosystems panel launches; and a venture to mine asteroids launches.

Envisat crisis rekindles row over funding for its successors.

Leeches provide traces of DNA from other species.

Upcoming docking of commercial supply craft heralds easier access to orbiting laboratory.

High-profile results challenged over statistical analysis of sequence data.

Two-billion-year barrage hit Earth when life was beginning.

But a plan to ramp up wind power could spark more conflict with indigenous groups.

Work on mutant flu caused a furore, but is far from the only subject in which risks might outweigh benefits.

A handful of plant collectors has shaped the field of botany. Now they are disappearing, and there are no clear successors.

Manufacturers of commercial reagents should follow scientific norms and be open about the ingredients of their products, says Anna Git.

Over-reliance on automated tools is hurting science, says David W. Piston.

We need to turn the efforts of social scientists towards global challenges, argues Luk Van Langenhove.

Simon Mawer relishes a masterful mix of neuroscience and art that focuses on the early twentieth century.

Stephen R. Palumbi finds both stark warnings and buoyant optimism in an encyclopaedic take on the state of the oceans.

Michael Shermer enjoys a reminder that cutting-edge research is a step into the unknown.

Highlights of this season's releases

James H. Fowler applauds a master biologist's model of the evolution of sociality.

Noel Sharkey is engaged by a take on the intriguing overlap between biology and robotics.

A multilayered tale centred on a nineteenth-century automaton grips Minsoo Kang.

Sonja Vermeulen ponders two takes on the twinned global issues of consumption and waste.

Nicola Clayton is fascinated by the mind of the crow, and the bird's ancient links with humankind.

An article suggesting that allergic responses may not be an accident of an off-target immune system, but rather a deliberate defence against potential harm, provokes the question of whether our understanding of allergy needs an overhaul. Immunologists provide their opinions. See Perspective p.465

Developing organs adapt dynamically to meet the changing needs of a growing organism. A study in zebrafish reveals surprising patterns of muscle growth that reshape the heart as it matures. See Article p.479

Laser-excited oscillations of ion crystals can be used to make ions interact like magnetic quantum particles. This mechanism has now been demonstrated in a large, two-dimensional ion lattice. See Letter p.489

The observation that old, massive galaxies have a larger fraction of low-mass stars than their younger, lower-mass counterparts adds to mounting evidence that star formation may have been different in the early Universe. See Letter p.485

A stepwise process of mutation and structural analysis has modulated a flexible binding interface of an immune-cell signalling protein, interleukin-2, and generated mutant proteins with enhanced anticancer activity. See Article p.529

A review of allergic host defences argues that allergic immunity has an important role in host defence against noxious environmental substances.

Genetically encoded neural activity markers were used in mice to simultaneously follow large populations of motor cortex neurons during sensorimotor learning, revealing that spatially intermingled neurons represent either sensory or motor behaviour, with population-level representations of subsets of motor programs strengthening as training progressed.

Using a conditional multicolour tracing approach, the contributions of individual cardiomyocytes to zebrafish heart morphogenesis are defined, revealing clonal dominance as a key mechanism.

A study of the stellar kinematics of a large sample of early-type galaxies provides evidence that the stellar initial mass function depends on the galaxy’s stellar mass-to-light ratio and thus is strongly dependent on the galaxy’s formation history.

A trapped-ion quantum simulator is used to demonstrate tunable long-range spin-spin couplings in two dimensions, relevant to studies of quantum magnetism at a scale that is intractable for classical computers.

The heavy-fermion compound YbRh₂Si₂ possesses a quantum critical point, at which the standard theory of electron behaviour in metals is expected to break down; such anomalous behaviour has now been observed.

The reappearance of major iron formations at 1.88 billion years ago (after the rise in atmospheric oxygen) is puzzling because their deposition requires anoxic and iron-rich sea water, but is here explained as a consequence of major mantle activity and rapid crustal growth at that time.

Using satellite laser altimetry, basal melting of ice shelves is determined to be the main driver of Antarctic ice-sheet loss,with changing climate the likely cause.

A theoretical model shows how sexual selection, on its own, can maintain biodiversity, provided that two realistic assumptions are met: that carrying capacity varies spatially, and that females searching for mates incur costs in doing so.

Dendritic cells in mice lacking NLRP10 are defective in exiting inflamed tissue, leading to impaired adaptive immunity; this could have a profound impact on the approach to treating allergic and autoimmune diseases.

Infection with Candida albicans and Staphylococcus aureus gives rise to T_H17 cells with different properties; microbe-induced T-cell differentiation is shown here to depend on the balance between polarizing cytokines rather than absolute amounts.

Interferon-inducible transmembrane (IFITM) protein 3 is shown to be an innate defence mechanism against viral infection in vivo; furthermore, a subset of the patients hospitalized during the H1N1 2009 pandemic carried a variant form of the IFITM3 gene.

Resolvins and protectins are anti-inflammatory and pro-resolving lipid mediators that are shown to resolve infections, and their administration lowers required doses of antibiotics and shortens infections.

Although IL-2 has been studied for its immune-stimulating activity against metastatic cancer, its side effects have limited its clinical use; here, an engineered IL-2 ‘superkine’ is shown to have increased activity, particularly in inducing antitumour T cells, but fewer side effects.

Centromere identity is thought to be epigenetically propagated by stable inheritance of nucleosomes containing the histone variant CENP-A; the authors propose a different model here in which germline transcription defines the genomic regions that exclude CENP-A incorporation during embryogenesis in the holocentric worm Caenorhabditis elegans.

Internal Shine–Dalgarno-like sequences in bacterial messenger RNA determine the elongation rate of protein synthesis and synonymous codon usage.

To maintain homeostasis in epithelial cell layers in Drosophila, cell overcrowding causes a proportion of cells to undergo a loss of cell adhesive junctions and be squeezed out by neighbouring cells.

Here it is shown that epithelia extrude live but not dying cells at sites of high strain, elucidating a mechanism for maintaining homeostatic cell numbers.

Having a mobile device can save researchers a huge amount of time. It can also mean that they never switch off.

International moves and multiple disciplines helped an astrophysicist to define her career path.

Sleep no more ...

Nature Outlook maps the challenges in tackling the malaria epidemic.

Signs of emerging drug resistance are turning the hunt for new malaria treatments into a race against the clock.

Even a cure is not preventing deaths from malaria in Uganda. Poor education and limited access to healthcare are among the reasons why.

Nine experts give their opinion on the 'known unknowns' in malaria research.

The nearly century-long search for a malaria vaccine might end in the bottom of a cup.

Preventing mosquitoes from transmitting the malaria parasite is a crucial piece of the eradication puzzle.

The war against the malaria parasite has raged for millennia, and still claims hundreds of thousands of lives each year. Resistance is a growing issue — for both the parasite to current therapy, and the mosquito to pesticides. Past attempts to eradicate malaria have failed. What will it take to finally subdue this deadly disease?