Volume 492 Issue 7427

Editorials

An unhealthy obsession p.7

The energy expended by US biomedical scientists on complaining about grant-application limits would be better directed at the real problem: stagnant funding.

doi: 10.1038/492007a

Suspend disbelief p.7

Wrangling over scientific misconduct could influence Romania’s general election.

doi: 10.1038/492007b

Haste not speed p.8

US science would benefit if Congress improved the predictability and stability of funding.

doi: 10.1038/492008a

News

News Features

The quantum space race p.22

Fierce rivals have joined forces in the race to teleport information to and from space.

doi: 10.1038/492022a

Radical reactors p.26

For decades, one design has dominated nuclear reactors while potentially better options were left by the wayside. Now, the alternatives might finally have their day.

doi: 10.1038/492026a

News & Views

OlfactionIntimate neuronal whispers p.44

It's a touching story of cohabitation and meaningful communication. Two neighbouring fruitfly neurons talk to each other not by means of synaptic junctions but by interactions through the surrounding electrical field. See Article  p.66

doi: 10.1038/nature11757

Organic chemistryToolkit of reagents to aid drug discovery p.45

Reagents have been developed that allow carbon—hydrogen bonds on benzene-like compounds called heterocycles to be converted directly into carbon—carbon bonds. The finding will be a boon to medicinal chemists. See Letter  p.95

doi: 10.1038/nature11760

Evolutionary genomicsAlgae's complex origins p.46

The nuclear genomes of two of nature's most complex cells have been sequenced. The data will help to determine the evolutionary path from symbioses between species to a multi-compartmental unicellular organism. See Article  p.59

doi: 10.1038/nature11759

Extrasolar planetsAstrophysical false positives p.48

The probability that giant-planet-like signals detected by the Kepler spacecraft are not from planets is higher than expected. The result underscores the importance of making follow-up observations to confirm the nature of the signals.

doi: 10.1038/492048a

BiochemistryAnother aspect of nature's ingenuity p.50

Eyewitnesses are sometimes asked to identify a culprit from a line-up of people associated with a crime scene. An enzyme — iridoid synthase — that catalyses an unusual reaction has been identified by a similar approach. See Letter  p.138

doi: 10.1038/nature11754

Applied physicsAn optical trampoline p.51

A neat study shows that a sheet of laser light can be used to reflect light-absorbing liquid droplets and manipulate their trajectories. This observation may open up new ways of controlling and studying aerosols.

doi: 10.1038/492051a

AstronomyA truly embryonic star p.52

The discovery of what may be the best example yet of a forming star caught in the moments just before birth provides a missing link in our understanding of how giant gas clouds collapse to form fully fledged stars. See Letter  p.83

doi: 10.1038/492052a

Articles

Algal genomes reveal evolutionary mosaicism and the fate of nucleomorphs p.59

Cryptophyte and chlorarachniophyte algae are transitional forms in the widespread secondary endosymbiotic acquisition of photosynthesis by engulfment of eukaryotic algae. Unlike most secondary plastid-bearing algae, miniaturized versions of the endosymbiont nuclei (nucleomorphs) persist in cryptophytes and chlorarachniophytes. To determine why, and to address other fundamental questions about eukaryote–eukaryote endosymbiosis, we sequenced the nuclear genomes of the cryptophyte Guillardia theta and the chlorarachniophyte Bigelowiella natans. Both genomes have >21,000 protein genes and are intron rich, and B. natans exhibits unprecedented alternative splicing for a single-celled organism. Phylogenomic analyses and subcellular targeting predictions reveal extensive genetic and biochemical mosaicism, with both host- and endosymbiont-derived genes servicing the mitochondrion, the host cell cytosol, the plastid and the remnant endosymbiont cytosol of both algae. Mitochondrion-to-nucleus gene transfer still occurs in both organisms but plastid-to-nucleus and nucleomorph-to-nucleus transfers do not, which explains why a small residue of essential genes remains locked in each nucleomorph.

doi: 10.1038/nature11681

Non-synaptic inhibition between grouped neurons in an olfactory circuit p.66

Diverse sensory organs, including mammalian taste buds and insect chemosensory sensilla, show a marked compartmentalization of receptor cells; however, the functional impact of this organization remains unclear. Here we show that compartmentalized Drosophila olfactory receptor neurons (ORNs) communicate with each other directly. The sustained response of one ORN is inhibited by the transient activation of a neighbouring ORN. Mechanistically, such lateral inhibition does not depend on synapses and is probably mediated by ephaptic coupling. Moreover, lateral inhibition in the periphery can modulate olfactory behaviour. Together, the results show that integration of olfactory information can occur via lateral interactions between ORNs. Inhibition of a sustained response by a transient response may provide a means of encoding salience. Finally, a CO2-sensitive ORN in the malaria mosquito Anopheles can also be inhibited by excitation of an adjacent ORN, suggesting a broad occurrence of lateral inhibition in insects and possible applications in insect control.

doi: 10.1038/nature11712

The entorhinal grid map is discretized p.72

The medial entorhinal cortex (MEC) is part of the brain’s circuit for dynamic representation of self-location. The metric of this representation is provided by grid cells, cells with spatial firing fields that tile environments in a periodic hexagonal pattern. Limited anatomical sampling has obscured whether the grid system operates as a unified system or a conglomerate of independent modules. Here we show with recordings from up to 186 grid cells in individual rats that grid cells cluster into a small number of layer-spanning anatomically overlapping modules with distinct scale, orientation, asymmetry and theta-frequency modulation. These modules can respond independently to changes in the geometry of the environment. The discrete topography of the grid-map, and the apparent autonomy of the modules, differ from the graded topography of maps for continuous variables in several sensory systems, raising the possibility that the modularity of the grid map is a product of local self-organizing network dynamics.

doi: 10.1038/nature11649

Letters

Extremely metal-poor gas at a redshift of 7 p.79

The spectrum of a quasar at redshift 7.04 reveals absorption from a large column of foreground neutral hydrogen with no corresponding heavy elements; this absorbing gas is either diffuse and intergalactic but has not yet been ionized by starlight at this early epoch, or it is gravitationally bound to a proto-galaxy that has a chemical abundance <1/10,000 the solar level.

doi: 10.1038/nature11612

Continuous gas-phase synthesis of nanowires with tunable properties p.90

Aerotaxy, an aerosol-based growth method, is used to produce gallium arsenide nanowires with a growth rate of about 1 micrometre per second, which is 20 to 1,000 times higher than previously reported for traditional nanowires and allows sensitive and reproducible control of the nanowires’ optical and electronic properties.

doi: 10.1038/nature11652

Practical and innate carbon–hydrogen functionalization of heterocycles p.95

It is shown that zinc sulphinate salts can be used to transfer alkyl radicals to heterocycles, allowing for the mild, direct and operationally simple formation of medicinally relevant carbon–carbon bonds while reacting in a complementary fashion to other innate carbon–hydrogen functionalization methods.

doi: 10.1038/nature11680

The root of branching river networks p.100

Models and field measurements together show that the branching patterns of fine-scale river networks are the result of coupled instabilities in the erosional processes that drive valley incision.

doi: 10.1038/nature11672

Fucose sensing regulates bacterial intestinal colonization p.113

FusKR, a fucose-sensing two-component system, has been identified in enterohaemorrhagic E. coli, linking fucose utilization and virulence factor gene expression and providing insight into how sensing of a host signal can facilitate bacterial colonization.

doi: 10.1038/nature11623

Structure of a force-conveying cadherin bond essential for inner-ear mechanotransduction p.128

A combination of structural, computational and biophysical tools is used to characterize the bond between tip-link proteins protocadherin 15 and cadherin 23, which have an essential role in inner-ear mechanotransduction; the bond, involving an extended protein handshake, is found to be affected by deafness mutations and is mechanically strong enough to resist forces in hair cells, adding to our understanding of hair-cell sensory transduction and interactions among cadherins.

doi: 10.1038/nature11590