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Speciation in colour: a textbook example of evolution in action The cichlid fish of African lakes are textbook examples of rapid speciation but the mechanisms involved remain elusive. Observations of the cichlids in Lake Victoria now demonstrate the ecological and molecular basis of divergent evolution of the visual system (seen as divergence of vision genes, male coloration and female preferences) leading to speciation by sensory drive through interacting natural and sexual selection. The sensory drive hypothesis predicts that divergent adaptation in sensory and signalling systems to different environments can cause premating isolation between populations. As well as providing clear evidence that speciation can occur through sensory drive without geographical isolation, this work provides a mechanistic explanation for the collapse of cichlid fish species diversity during the anthropogenic eutrophication of Lake Victoria. On the cover, the colourful cichlids Pundamilia nyererei and Pundamilia pundamilia, as well as a wild intermediate (top) with the light spectra from different water depths in the background. [Article p. 620; News & Views p. 601; www.nature.com/podcast] Cover images: Ole Seehausen & Inke van der Sluijs.
The turmoil in the financial markets could lead to severe cost-cutting by governments, but US politicians would do well to note the benefits of continued support for clean energy and climate policies.
What began several years ago as an attempt to recruit social scientists to help the military has sparked a broader debate about militarizing academia. Sharon Weinberger reports.
Cell therapies are as much about the patients as they are about the cells. Monya Baker meets two stem-cell scientists who have decided to put people first.
Researchers need to get past the standard model of vaccine development and focus on how immune responses are specifically tailored to retroviruses, argue Ruslan Medzhitov and Dan Littman.
The field is healthy, says Bill Wakeham, but scientists need to reclaim the intellectual ownership of research at the margins of the discipline such as medical or atmospheric physics.
Artist Karel Nel works with astronomers from COSMOS, the global Cosmic Evolution Survey that is mapping galaxies and dark matter. Now exhibiting his work in London, he tells Nature how his view of the Universe has changed.
Botanic gardens are using good garden design to attract and educate the public. Mike Maunder explains how they can thrive both as businesses and as institutions of learning.
Two decades ago, Deng Xiaoping welcomed nations to an international meeting in Beijing. Mohamed Hassan recalls how China's leaders set out their plans for the nation to rejoin the world's scientific elite.
Adaptation of a fish's eyes to its visual environment can bias females to mate with different males according to their coloration. This sensory preference can contribute to the formation of new species.
The concentration of atmospheric carbon dioxide decreased between 45 million and 25 million years ago, a trend accompanied by glaciation at the poles. Modelling results suggest when and where the ice closed in.
To make one differentiated cell type from another, a 'stopover' at an undifferentiated state is often required. An alternative method offering an efficient direct route could have implications for disease treatment.
The origin of the current AIDS pandemic has been a subject of great interest and speculation. Viral archaeology sheds light on the geography and timescale of the early diversification of HIV-1 in humans.
A general method for detecting nuclear magnetic resonance signals from a single molecule has so far been elusive. Magnetic sensors that exploit crystal imperfections in diamond might make such a method a reality.
Dopamine dysfunction, which is implicated in Parkinson's disease and drug addiction, seems an unlikely culprit in fragile X syndrome. A surprising set of findings means a rethink is required.
HIV has advanced from high-risk groups such as intravenous drug users to some in the general population, according to comprehensive new data from the south of China. What needs to be done to halt its spread?
This paper identifies the ecological and molecular basis of divergent evolution in the visual system of Lake Victoria cichlid fishes, leading to speciation through sensory drive without geographical isolation.
This paper shows that exocrine cells of the pancreas can be converted in vivo to insulin-secreting endocrine cells. Interestingly, the transdifferentiating cells did not have to revert to a more primitive, pluripotent state in this process, but seemed to move directly from one differentiated state to another.
To prevent the tips of chromosomes from becoming shorter with each round of DNA duplication and cell division, telomerase extends the telomere lagging strand so that it matches the full length of the telomere leading strand. This paper presents the structure of the catalytic subunit of telomerase. By modelling in a hybrid RNA–DNA molecule, it is possible to visualize how the end of the DNA primer is positioned within the enzyme's active site.
The rate of star formation in a galaxy is often determined by the observation of emission in the Hα line, which is related to the presence of short-lived massive stars. This paper shows that a local formulation of the concept of clustered star formation naturally leads to a steeper radial decrease of the Hα surface luminosity than the star-formation-rate surface density and that the observed Hα cutoff arises naturally.
A naturally occurring impurity in diamond crystals, the nitrogen-vacancy centre, has been found to have a unique, long-lived single electron spin state that can be controlled and detected optically. An approach to magnetic sensing by coherent control of such diamond spins is demonstrated, and it is shown that precision measurements of nanoTesla magnetic fields are in principle possible.
The nitrogen-vacancy (NV) centre, a naturally occurring impurity in diamond crystals, has a unique, long-lived single-electron spin state that can be controlled and detected optically. This paper demonstrates the first steps towards a sensitive, high-resolution imaging technique in which these diamond spins are exploited. It is shown that the location of single NV spins can be determined with nanometre scale resolution, at ambient conditions, using magneto-optical spin detection.
It is widely accepted that an ice-covered Antarctica first occurred ∼34 million years ago, but the glacial history of the northern hemisphere is less clear. This paper investigates the possibilities of when the continental-scale glaciation of the north occurred with a global climate/ice-sheet model that takes into account the long-term decline of atmospheric CO2 levels during this period. The CO2 threshold for glaciation in the north seems to be much lower, and so will have been crossed much later than ∼34 million years ago, suggesting that episodic northern-hemispheric ice sheets have been possible only for the past ∼25 million years.
This paper presents plastic deformation experiments of polycrystalline akimotoite. It is shown that a change develops in the crystallographic preferred orientation pattern of akimotoite with temperature, with the c-axis maximum parallel to the compression direction developing at high temperature, whereas the c-axes are preferentially oriented parallel to the shear direction or perpendicular to the compression direction at lower temperatures.
Newly isolated HIV genome sequences from a 1960 biopsy sample from Kinshasa are analysed in comparison with the viral sequence from 1959. The analysis presents supporting evidence that diversification of HIV-1 in west-Central Africa occurred long before the recognized AIDS pandemic.
The 'Approximate number system' (ANS), a relatively imprecise discrimination of quantities and numbers, has been demonstrated in cultures with no verbal counting system and even in various non-human species. Children with higher symbolic math abilities also do ANS tasks more precisely, and do this regardless of their general verbal IQ or visual–spatial reasoning skills.
In nematodes, the extracellular molecule UNC6/netrin is required both in the vicinity of dendrites to prevent mislocalization of axonal proteins there, and sufficient to exclude synaptic proteins from axon terminals if artificially provided close to these. The results extend to another extracellular protein, Wnt, and suggest that axon guidance cues also control local exclusion of axon terminal components from dendrites.
STING is an activator of IRF3 and NF-κB in response to RNA and DNA viruses. It localizes to the endoplasmic reticulum and interacts with both RIG-I and the translocon adaptor SEC61β implicating the translocon in innate immune signalling.
c-Myc acts as oncogen in many tumours, often due to its amplification and/or overexpression. This study investigates whether inhibition of endogenous Myc in tumours driven by other oncogenes may also interfere with tumour growth. This was found to be the case. Although systemic inhibition of Myc has effects in other tissues, these were found to be reversible, suggesting that Myc might be a valid anti-cancer target.
Although two eukaryotic initiation factors (eIFs) are known to transmit signals to the small ribosomal subunit, it was unknown whether an eIF served a similar function for the large ribosomal subunit. This study shows that eIF6 communicates extracellular signals to the 60S subunit. Cells from an eIF6 heterozygous mouse show normal ribosome biogenesis but reduced translation, delayed cell cycle progression, and impaired transformation.
DNA can be repaired by two different mechanisms, depending on whether a homologous template is available. Thus, homologous recombination is restricted to S and G2 phases of the cell cycle. The activity of cyclin-dependent kinases (CDKs) is also cell cycle regulated, and the yeast CDK Cdc28 controls DNA resection, an early step of homologous recombination. This work shows that the target of Cdc28 in regulating DNA resection is Sae2.
HIV-1 protease processes the Gag and Gag-Pol polyproteins into mature structural and functional proteins. The mature protease is only active as a dimer, with catalytic residues contributed by each subunit. The precursor of the active protease undergoes 'maturation' via the intramolecular cleavage of a dimeric species, but it is not clear how this cleavage reaction occurs. The early events in N-terminal auto-processing were visualized using NMR spectroscopy, and it was determined that the precursor forms transient, lowly populated dimeric encounter complexes that occupy a wide range of orientations relative to the mature dimer. The N-terminal region makes transient intra- and intersubunit contacts with the substrate binding site, enabling auto-cleavage to occur when the correct dimer orientation is sampled by the encounter complex ensemble.
Until now, metabolomics researchers have had to adapt technology developed mainly for proteomics. But there are now solutions designed with them in mind. Nathan Blow reports.