Table of contents

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Open sesame p813

Government influence favouring enhanced openness is rightly diversifying practices in science publishing.


Learning in the wild p813

Much of what people know about science is learned informally. Education policy-makers should take note.


Attention Canadian mentors p814



Research Highlights

Wildlife biology: Pitch shifter p816


Palaeoecology: Ancient tree nursery p816


Cancer biology: Brain tumour trigger p816


Chemical sensing: Bomb detector sewn up p816


Immunology: Secret to superinfection p816


Cancer detection: Tracking roving cancer cells p817


Plant biology: Seeking enlightenment p817


Animal behaviour: Tortoise see, tortoise do p817


Neurobiology: Entangled diseases p817



Journal Club

Journal club p817

C. Oliver Kappe




News briefing: 8 April 2010 p818

The week in science.


Telescope arrays give fine view of stars p820

Optical interferometry is no longer on the fringe of astronomy.

Eric Hand


Charities warm to climate p821

Philanthropic support for climate-change issues tripled in 2008.

Laura Thompson Osuri


US seeks to make science free for all p822

Moves to make research funded by the US government available to everyone could mark a turning point in a publishing revolution. Declan Butler reports.

Declan Butler


What's in a name? Fly world is abuzz p825

Proposed reorganization of Drosophila fruitfly genus might throw out its most celebrated member.

Rex Dalton


Animals thrive without oxygen at sea bottom p825

Creatures found where only microbes and viruses were thought to survive.

Janet Fang



Correction p825



News Features

Archaeology: Hidden treasure p826

The explosion in commercial archaeology has brought a flood of information. The problem now is figuring out how to find and use this unpublished literature, reports Matt Ford.


Protein folding: The dark side of proteins p828

Almost every human protein has segments that can form amyloids, the sticky aggregates known for their role in disease. Yet cells have evolved some elaborate defences, finds Jim Schnabel.




PhD: routine technical work of sequencing is no substitute p831

Yijun Chen


PhD: still necessary for independent research leaders p831

Yonghong Li


PhD: time and effort invested foster scientific maturity p831

Biswa Prasun Chatterji


Food security requires genetic advances to increase farm yields p831

Richard C. Leegood, John R. Evans & Robert T. Furbank




How is the Global Green New Deal going? p832

China and South Korea have invested heavily in environmental stimulus projects. Other G20 countries need to deliver on their sustainability promises to save both the planet and the economy, says Edward Barbier.

Edward Barbier


Correction p833



Books and Arts

Why music moves us p834

Daniel J. Levitin enjoys a book that explains how rhythm, pitch and timbre are combined, and why the most delightful compositions balance predictability and surprise.

Daniel J. Levitin reviews The Music Instinct: How Music Works and Why We Can't Do Without It by Philip Ball


Once more into the animal mind p835

Nicky Clayton reviews Cognition, Evolution, and Behavior by Sara J. Shettleworth


Smithsonian on human origins p836

Janet Fang reviews David H. Koch Hall of Human Origins


Books in brief p836

Joanne Baker


Correction p836



News and Views

Microbiology: Genetic pot luck p837

Without the trillions of microbes that inhabit our gut, we can't fully benefit from the components of our diet. But cultural differences in diet may, in part, dictate what food our gut microbiota can digest.

Justin L. Sonnenburg


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

Human evolution: Stranger from Siberia p838

The sequencing of ancient DNA is generating dramatic results. The sequence from a bone fragment has revealed the existence of an unknown type of extinct human ancestor that lived in Asia 40,000 years ago.

Terence A. Brown


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

Microfluidics: Exploiting elephants in the room p839

Microfluidic devices have many applications in chemistry and biology, but practical hitches associated with their use are often overlooked. One such device that optimizes catalysts tackles these issues head-on.

Robert C. R. Wootton & Andrew J. deMello


Evolutionary biology: A flourishing of fish forms p840

According to an innovative exercise in 'morphospace analysis', modern fish owe their stunning diversity in part to an ecological cleaning of the slate by the mass extinction at the end of the Cretaceous.

Michael Alfaro & Francesco Santini


Stellar astrophysics: Shrouded in a dusty disk p842

For more than a century, the binary star system ϵ Aurigae has been a riddle, wrapped in a mystery, inside an enigma. But no more — the system's previously inferred but unseen disk of dust has been detected.

Edward Guinan


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

Climate change: Grazing and nitrous oxide p843

Most emissions of nitrous oxide from semi-arid, temperate grasslands usually occur during the spring thaw. The effects that grazing has on plant litter and snow cover dramatically reduce these seasonal emissions.

Stephen J. Del Grosso


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

Cancer: Drug-tolerant insurgents p844

Some cancer cells that become tolerant to a drug remain resistant even after its withdrawal, yet these cells eventually become sensitive to the drug again. The underlying molecular mechanism is unusual.

Paul Workman & Jon Travers




Quantum spin liquid emerging in two-dimensional correlated Dirac fermions p847

A quantum spin liquid is a hypothetical system of spins (such as those carried by electrons), the orientations of which continue to fluctuate even at absolute zero. Theoretical and experimental evidence for the existence of such states at the microscopic level is elusive, but these authors have modelled correlated electrons arranged on a honeycomb lattice (such as in graphene), and identified the conditions under which a microscopic quantum spin liquid would be realized in two dimensions.

Z. Y. Meng, T. C. Lang, S. Wessel, F. F. Assaad & A. Muramatsu


See also: Editor's summary

Bone progenitor dysfunction induces myelodysplasia and secondary leukaemia p852

A new mouse model is developed in which haematopoietic malignancies are caused by genetic changes in the microenvironment of blood cells. Deletion in bone progenitor cells of Dicer1, a gene involved in microRNA processing, leads to a myelodysplastic syndrome-like phenotype which can progress to leukaemia. Deregulation of Sbds, which is mutated in human Schwachman–Bodian–Diamond syndrome, may be involved in this process.

Marc H. G. P. Raaijmakers, Siddhartha Mukherjee, Shangqin Guo, Siyi Zhang, Tatsuya Kobayashi, Jesse A. Schoonmaker, Benjamin L. Ebert, Fatima Al-Shahrour, Robert P. Hasserjian, Edward O. Scadden, Zinmar Aung, Marc Matza, Matthias Merkenschlager, Charles Lin, Johanna M. Rommens & David. T. Scadden


See also: Editor's summary

Zscan4 regulates telomere elongation and genomic stability in ES cells p858

Zscan4 is shown to be involved in maintaining telomeres in embryonic stem (ES) cells. Only 5% of ES cells express Zscan4 at a given time, but nearly all ES cells activate Zscan4 at least once within nine passages. The transient Zscan4-positive state is associated with rapid telomere extension by telomere recombination and upregulation of meiosis–specific homologous recombination genes. Knocking down Zscan4 shortens telomeres, increases karyotype abnormalities and spontaneous sister chromatid exchange, and slows down cell proliferation until reaching crisis by eight passages.

Michal Zalzman, Geppino Falco, Lioudmila V. Sharova, Akira Nishiyama, Marshall Thomas, Sung-Lim Lee, Carole A. Stagg, Hien G. Hoang, Hsih-Te Yang, Fred E. Indig, Robert P. Wersto & Minoru S. H. Ko


See also: Editor's summary

Molecular mechanism of multivesicular body biogenesis by ESCRT complexes p864

Here, multivesicular body (MVB) biogenesis is reconstituted using giant unilamellar vesicles and all of the ESCRT complexes. ESCRT-0 is required for clustering of cargo proteins, whereas ESCRT-I and -II in combination deform the membrane into buds, in which cargo is confined. ESCRT-III subunits localize to the bud neck and are required for scission of the membrane to form intraluminal vesicles. These results explain how ESCRT complexes sequester cargo proteins into MVBs.

Thomas Wollert & James H. Hurley


See also: Editor's summary



Infrared images of the transiting disk in the ϵ Aurigae system p870

ϵ Aurigae is a bright, eclipsing binary star system but the cause of each 18-month-long eclipse has been unknown for nearly 190 years, because the companion was, until recently, undetectable. The preferred explanation has been a tilted disk of opaque material and here the authors report interferometric images that do indeed show an opaque disk of very low mass, tilted as expected, crossing the disk of the F star.

Brian Kloppenborg, Robert Stencel, John D. Monnier, Gail Schaefer, Ming Zhao, Fabien Baron, Hal McAlister, Theo ten Brummelaar, Xiao Che, Chris Farrington, Ettore Pedretti, P. J. Sallave-Goldfinger, Judit Sturmann, Laszlo Sturmann, Nathalie Thureau, Nils Turner & Sean M. Carroll


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

‘Memristive’ switches enable ‘stateful’ logic operations via material implication p873

A challenge in the semiconductor industry is to create integrated circuits that use new physical state variables — other than charge or voltage — to offer memory and logic functions. Memristive devices, which combine the electrical properties of a memory element and a resistor, use resistance instead, and here such 'memristors' are shown to perform logic operations as well.

Julien Borghetti, Gregory S. Snider, Philip J. Kuekes, J. Joshua Yang, Duncan R. Stewart & R. Stanley Williams


See also: Editor's summary

Dislocation nucleation governed softening and maximum strength in nano-twinned metals p877

The strength of conventional metals is determined by the interaction of dislocations with obstacles such as grain boundaries. Molecular dynamics simulations reveal that the strength of ultrafine-grained copper containing twin boundaries can be controlled by a dislocation nucleation mechanism activated below a critical twin thickness. Below this thickness the material becomes softer. The smaller the grains, the smaller the critical twin boundary spacing, and the higher the metal's maximum strength.

Xiaoyan Li, Yujie Wei, Lei Lu, Ke Lu & Huajian Gao


See also: Editor's summary

Grazing-induced reduction of natural nitrous oxide release from continental steppe p881

To examine the effect of increased livestock numbers on nitrous oxide emissions the authors report year-round nitrous oxide flux measurements at ten steppe grassland sites in Inner Mongolia. They find that nitrous oxide emission is much higher during spring thaw and is highest in ungrazed steppe, decreasing with increasing stocking rate, which suggests that grazing decreases rather than increases nitrous oxide emissions.

Benjamin Wolf, Xunhua Zheng, Nicolas Brüggemann, Weiwei Chen, Michael Dannenmann, Xingguo Han, Mark A. Sutton, Honghui Wu, Zhisheng Yao & Klaus Butterbach-Bahl


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

Seismic evidence for widespread western-US deep-crustal deformation caused by extension p885

Here a method of seismic wave imaging known as 'ambient noise' tomography is used to generate high-resolution images of seismic wave speeds in the crust and uppermost mantle. The observations reveal strong and uniform anisotropy — where waves travel through rock at different speeds depending on direction — in the deep crust in areas of the western United States that have undergone significant extension during the past 65 million years.

M. P. Moschetti, M. H. Ritzwoller, F. Lin & Y. Yang


See also: Editor's summary

Hierarchical group dynamics in pigeon flocks p890

How large groups of animals move in a coordinated way has defied complete explanation. Inability to track each member of a flock has hampered understanding of the behavioural rules governing flocks of birds. This, however, has been achieved for a small group of homing pigeons fitted with lightweight GPS loggers. A well–defined hierarchy is revealed — the average position of a pigeon within the flock strongly correlates with is position in the social hierarchy (a kind of airborne pecking order).

Máté Nagy, Zsuzsa Ákos, Dora Biro & Tamás Vicsek


See also: Editor's summary

The complete mitochondrial DNA genome of an unknown hominin from southern Siberia p894

Ancient mitochondrial DNA from a hominin individual who lived in the mountains of Central Asia between 48,000–30,000 years ago has been sequenced. Comparative genomics suggest that this mitochondrial DNA derives from an out-of-Africa migration distinct from the ones that gave rise to Neanderthals and modern humans. It also seems that this hominin lived in close spatio-temporal proximity to Neanderthals and modern humans.

Johannes Krause, Qiaomei Fu, Jeffrey M. Good, Bence Viola, Michael V. Shunkov, Anatoli P. Derevianko & Svante Pääbo


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

Genome-wide SNP and haplotype analyses reveal a rich history underlying dog domestication p898

An extensive genome-wide survey of over 48,000 single nucleotide polymorphisms in dogs and their wild progenitor, the grey wolf, was conducted to shed light on the process of dog diversification. The results reveal that much of genome diversity came from Middle Eastern progenitors, combined with interbreeding with local wolf populations, and that recent evolution involved limited genetic variation to create the phenotypic diversity of modern dogs.

Bridgett M. vonHoldt, John P. Pollinger, Kirk E. Lohmueller, Eunjung Han, Heidi G. Parker, Pascale Quignon, Jeremiah D. Degenhardt, Adam R. Boyko, Dent A. Earl, Adam Auton, Andy Reynolds, Kasia Bryc, Abra Brisbin, James C. Knowles, Dana S. Mosher, Tyrone C. Spady, Abdel Elkahloun, Eli Geffen, Malgorzata Pilot, Wlodzimierz Jedrzejewski, Claudia Greco, Ettore Randi, Danika Bannasch, Alan Wilton, Jeremy Shearman, Marco Musiani, Michelle Cargill, Paul G. Jones, Zuwei Qian, Wei Huang, Zhao-Li Ding, Ya-ping Zhang, Carlos D. Bustamante, Elaine A. Ostrander, John Novembre & Robert K. Wayne


See also: Editor's summary

Human memory strength is predicted by theta-frequency phase-locking of single neurons p903

Although explored in the rodent, the relationship between single neuron activity, oscillations and behavioural learning is unknown in humans. Here, successful memory formation in humans was predicted by the coordination of spike timing relative to the local theta oscillation. These data provide a direct connection between the behavioural modulation of oscillations and plasticity within specific circuits.

Ueli Rutishauser, Ian B. Ross, Adam N. Mamelak & Erin M. Schuman


See also: Editor's summary

Transfer of carbohydrate-active enzymes from marine bacteria to Japanese gut microbiota p908

One of the roles of the human gut microbiota is to break down nutrients using bacterial enzymes that are lacking from the human genome. It is now shown that the gut microbiota of Japanese, but not American, individuals contains porphyranases, enzymes that digest sulphated polysaccharides which are present in the marine environment only. These findings indicate that diet can select for gene content of the human microbiota.

Jan-Hendrik Hehemann, Gaëlle Correc, Tristan Barbeyron, William Helbert, Mirjam Czjzek & Gurvan Michel


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

MONOPTEROS controls embryonic root initiation by regulating a mobile transcription factor p913

During Arabidopsis embryogenesis, a single cell is specified to become the founder cell of the root meristem — the hypophysis — in response to signals from adjacent cells. Hypophysis specification requires an auxin-responsive transcription factor, MONOPTEROS (MP), which promotes transport of auxin from the embryo to the hypophysis precursor. Here, MP target genes are identified and the means by which they mediate root formation is shown.

Alexandra Schlereth, Barbara Möller, Weilin Liu, Marika Kientz, Jacky Flipse, Eike H. Rademacher, Markus Schmid, Gerd Jürgens & Dolf Weijers


See also: Editor's summary

Vascular endothelial growth factor B controls endothelial fatty acid uptake p917

VEGF–B is shown to have an unexpected role in targeting lipids to peripheral tissues. VEGF–B controls endothelial uptake of fatty acids via transcriptional regulation of vascular fatty acid transport proteins. Bioinformatic analyses suggest that the uptake of these lipids is tightly coupled with lipid use by mitochondria. Mice that do not have VEGF–B accumulate less lipids in muscle, heart and brown adipose tissue, and instead shunt them to white adipose tissue.

Carolina E. Hagberg, Annelie Falkevall, Xun Wang, Erik Larsson, Jenni Huusko, Ingrid Nilsson, Laurens A. van Meeteren, Erik Samen, Li Lu, Maarten Vanwildemeersch, Joakim Klar, Guillem Genove, Kristian Pietras, Sharon Stone-Elander, Lena Claesson-Welsh, Seppo Ylä-Herttuala, Per Lindahl & Ulf Eriksson


See also: Editor's summary

Chromatin signature of embryonic pluripotency is established during genome activation p922

To study the changes in chromatin structure that accompany zygotic genome activation and pluripotency during the maternal–zygotic transition (MZT), the genomic locations of histone H3 modifications and RNA polymerase II have been mapped during this transition in zebrafish embryos. H3 lysine 27 trimethylation and H3 lysine 4 trimethylation are only detected after MZT; evidence is provided that the bivalent chromatin domains found in cultured embryonic stem cells also exist in embryos.

Nadine L. Vastenhouw, Yong Zhang, Ian G. Woods, Farhad Imam, Aviv Regev, X. Shirley Liu, John Rinn & Alexander F. Schier


See also: Editor's summary

Proviral silencing in embryonic stem cells requires the histone methyltransferase ESET p927

Endogenous retroviruses (ERVs) are widely dispersed in mammalian genomes, and are silenced in somatic cells by DNA methylation. Here, an ERV silencing pathway independent of DNA methylation is shown to operate in embryonic stem cells. The pathway involves the histone H3K9 methyltransferase ESET and might be important for ERV silencing during the stages in embryogenesis when DNA methylation is reprogrammed.

Toshiyuki Matsui, Danny Leung, Hiroki Miyashita, Irina A. Maksakova, Hitoshi Miyachi, Hiroshi Kimura, Makoto Tachibana, Matthew C. Lorincz & Yoichi Shinkai


See also: Editor's summary

The kinetics of two-dimensional TCR and pMHC interactions determine T-cell responsiveness p932

Quantification of the interaction of T-cell receptors with their peptide–MHC ligands in two–dimensional membranes is shown to yield larger dissociation rate constants than previous assays where one of the interacting partners was in solution.

Jun Huang, Veronika I. Zarnitsyna, Baoyu Liu, Lindsay J. Edwards, Ning Jiang, Brian D. Evavold & Cheng Zhu


See also: Editor's summary

Double Holliday junctions are intermediates of DNA break repair p937

In meiotic cells paired homologues are joined by a set of crossovers known as a double Holliday junction (DHJ). Whether DHJs form during mitotic recombination has been unclear, as mitotic cells possess alternative repair pathways that would not require DHJ formation. Here it is demonstrated that mitotic and meiotic cells form similar DHJs, but that the levels in mitotic cells are approximately 10–fold lower, and show a preference for joints between sister chromatids rather than homologues. Consequently, in mitotic cells non–crossover outcomes are favoured.

Malgorzata Bzymek, Nathaniel H. Thayer, Steve D. Oh, Nancy Kleckner & Neil Hunter


See also: Editor's summary



Homotypic fusion of ER membranes requires the dynamin-like GTPase Atlastin p942

Genny Orso, Diana Pendin, Song Liu, Jessica Tosetto, Tyler J. Moss, Joseph E. Faust, Massimo Micaroni, Anastasia Egorova, Andrea Martinuzzi, James A. McNew & Andrea Daga




A canine distemper virus epidemic in Serengeti lions (Panthera leo) p942

Melody E. Roelke-Parker, Linda Munson, Craig Packer, Richard Kock, Sarah Cleaveland, Margaret Carpenter, Stephen J. O’Brien, Andreas Pospischil, Regina Hofmann-Lehmann, Hans Lutz, George L. M. Mwamengele, M. N. Mgasa, G. A. Machange, Brian A. Summers & Max J. G. Appel




Transient FTY720 treatment promotes immune-mediated clearance of a chronic viral infection p942

Mary Premenko-Lanier, Nelson B. Moseley, Sarah T. Pruett, Pablo A. Romagnoli & John D. Altman




Maharashtra by the numbers p944

Bangalore and the south may be India's main information-technology centre, but the country's science hub arguably lies within the state of Maharashtra, home to the cities of Mumbai and Pune.

K. S. Jayaraman


Careers Q&A

Sanjay Singh p944

Sanjay Singh, chief executive of Gennova Biopharmaceuticals in Pune and former head of malaria-vaccine antigen research for the US National Institutes of Health, talks of Maharashtra's research potential.

K. S. Jayaraman



The path less travelled p945

The academic track is riddled with risks, yet most still believe it to be the safest career route for the devoted scientist. Andrea Schweitzer suggests a different way.

Andrea Schweitzer




Memory sticks p948

Total recall.

Steve Longworth


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