This press release contains:
---Summaries of newsworthy papers:
Evolution: Mammals diversified before dinosaurs’ demise
Geoscience: Ice sheet contribution to sea level changes
Comment: A plan for brain diseases
Neuroscience: Neural circuit underlying feeding behaviour in mice
Outlook: Super carbon
Virology: Influenza dodges antiviral responses through histone mimicry
Evolution: Tracing the origins of vertebrate brain complexity
Synthetic chemistry: Copy catalysts
Materials science: Origami with a twist
Quantum physics: Probing complex materials
And finally... Monitoring mice in mazes
---Mention of papers to be published at the same time with the same embargo
---Geographical listing of authors
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[1] Evolution: Mammals diversified before dinosaurs’ demise (AOP)
DOI: 10.1038/nature10880
The rodent-like mammals known as multituberculates, which lived alongside dinosaurs, may have diversified much earlier than previously thought. Analysis of the teeth of these mammals, reported in Nature, suggests their ecological diversity increased some 20 million years before the dinosaurs’ demise.
The Cretaceous–Paleogene mass extinction event, which took place around 66 million years ago, is considered to have been the trigger for the diversification of mammals. Prior to this time, mammals are thought to have been small bodied and under selection pressure from dinosaurs. However, the multituberculates were a successful group of mammals that prospered under the dinosaurs and survived the extinction.
Gregory Wilson and colleagues tracked the diversity of these animals by analysing changes in dental complexity and body size. Their findings suggest that the multituberculates evolved to eat plants long before the extinction of dinosaurs. This adaptive shift towards herbivory may have been in response to the evolution and diversification of flowering plants at the same time.
CONTACT
Gregory Wilson (University of Washington, Seattle, WA, USA)
Tel: +1 206 543 8917; E-mail: [email protected]
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[2] Geoscience: Ice sheet contribution to sea level changes (AOP)
DOI: 10.1038/nature10891
Accounting for how the Earth’s surface ‘bounces back’ following ice mass loss can help to improve estimates of sea level changes between periods of glaciation. Considering this factor, a study published in Nature suggests that the sea level during an unusually long warm interval during the ice age was lower than previously estimated. From these calculations, the contributions of polar ice sheets to sea level change can be better constrained.
Ice sheets in Greenland and West Antarctica are considered the most susceptible to climate change, whereas the stability of the East Antarctic Ice Sheet is less certain. Some calculations of sea level changes in the Bahamas and Bermuda during a period of warming around 400,000 years ago suggest that the sea rose by more than 20 metres. This estimate would suggest that a substantial loss of the East Antarctic Ice Sheet contributed to the rising waters.
However, Maureen Raymo and Jerry Mitrovica consider the elastic response of the Earth’s surface following ice mass loss and recalculate the sea level rise during this time to be around 6–13 metres. From this finding, the authors infer that the Greenland and West Antarctic ice sheets collapsed, but that mass loss from the East Antarctic Ice Sheet was minor.
CONTACT
Maureen Raymo (Columbia University, Palisades, NY, USA)
Tel: +1 845 365 8801; E-mail: [email protected]
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Comment: A plan for brain diseases (pp 267-269)
No chronic disease burdens the world more than mental illness. And yet, we are experiencing a crisis in the development of drugs for mental disorders and for neurological disease and traumas such as spinal cord and brain injuries; companies are withdrawing from the field or dramatically redirecting their investments. Two Comment pieces in this week’s Nature suggest ways of breaking through this impasse and getting neurological drug development going again.
In one article, Thomas Insel, Barbara Sahakian and others call for a fundamental change in almost all aspects of translational research in mental health — the conclusion of a meeting convened by The Royal Society in London. Their solutions include mining modern genetics to identify new treatment targets other than the monoamines, which have dominated psychiatric medicine for half a century; developing ways to detect mental illness in its earliest stages; and integrating therapies with psychosocial approaches such as cognitive behavioural therapy.
In a second piece, Martin Schwab and Anita Buchli propose how to tackle the problems that have stalled drug development by, for example, using public funds for small trials of promising compounds. They argue that brain disorders pose a greater socio-economic burden ― through healthcare costs and lost productivity ― than cancer, cardiovascular diseases and diabetes combined, yet do not receive commensurate research funding. “Now that drug companies have pulled out of this area, cancer funding is likely to eclipse that of neuroscience,” they write. “Funding agencies must revise their global budgets, in order to reflect the immediate and future medical needs of our society.”
CONTACT
Barbara Sahakian (University of Cambridge, UK)
E-mail: [email protected]
Martin Schwab (University of Zurich, Switzerland)
Tel: +41 44 635 3330; E-mail: [email protected]
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[3] Neuroscience: Neural circuit underlying feeding behaviour in mice (AOP)
DOI: 10.1038/nature10899
Experiments in mice that help define a neural circuit involved in modulating feeding behaviour and body weight are reported in Nature this week. Understanding this important pathway could be valuable for the development of novel treatments for diverse eating disorders, including anorexia nervosa, and nausea.
Although certain neurons known to promote feeding and weight gain have been identified, such as AgRP-expressing hypothalamic neurons, some components of the neuronal pathway involved have remained elusive. Richard Palmiter and colleagues identify a key role of a region in the midbrain called the parabrachial nucleus as a hub for integrating various inputs into this system. They show that using an anti-nausea drug called ondansetron to treat mice that lack AgRP neurons and that have ceased feeding, prevents fatal weight loss and allows the mice to recover. Ondansetron blocks serotonin from binding to its receptors, and the authors suggest that this alters the signalling output of the parabrachial nucleus. The study also underscores the roles of various neurotransmitters, including serotonin, in modulating feeding behavior.
CONTACT
Richard Palmiter (University of Washington, Seattle, WA, USA)
Tel: +1 206 543 6064; E-mail: [email protected]
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Outlook: Super carbon (pp S34 and S43)
Research into a two-dimensional form of carbon is proceeding along a dizzying variety of directions simultaneously, according to articles in Nature Outlook: Graphene.
Graphene ― which consists of a single atomic layer of carbon ― has a combination of extraordinary mechanical, electronic and optical properties. But although electrons can move through graphene faster than any other material, it is difficult to use for digital computer logic because a graphene transistor switch cannot be turned off, leading to power drain. Therefore, argues science writer Katherine Bourzac, graphene will probably have a greater impact in analogue devices, in which its ability to operate at high frequencies could prove beneficial for applications such as wireless signal processing. And graphene may be easier to integrate with silicon than other high-speed materials such as gallium arsenide.
In a separate piece, Michael Segal, a senior editor at Nature Nanotechnology, points out the similarities between graphene research and the early days of silicon. While now a primarily electronic material, silicon had its first major industrial use in the nineteenth century as an alloying agent for aluminium and steel. Similarly, the first commercial uses of graphene ― including security inks for consumer packaging, already on store shelves ― leave its advanced electronic properties unexploited. Just as the first silicon researchers could not have guessed its eventual ubiquity in computers, we may end up being surprised by graphene’s biggest application.
For background information, please contact the press office.
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[4] Virology: Influenza dodges antiviral responses through histone mimicry (AOP; N&V)
DOI: 10.1038/nature10892
A novel way in which the influenza virus interferes with host antiviral response is explained in Nature this week. An influenza protein mimics a cellular histone protein to hijack the host’s antiviral gene-expression machinery and contribute to the suppression of the antiviral response, according to the proposed mechanism.
Ivan Marazzi and co-workers show that the H3N2 subtype of influenza A exploits systems involved in gene regulation. An immunosuppressive protein encoded by the virus carries a histone-like sequence that reproduces key features of host histones, which are essential regulators of gene function. The authors show that these ‘histone mimics’ can bind to important transcriptional regulators, thereby affecting transcription and expression of antiviral genes.
Marazzi and colleagues identify a key mediator of this process, called hPAF1C, which the influenza histone mimic targets to suppress the antiviral response. These findings may pave the way for developing therapies that selectively interfere with hPAF1C binding, the authors suggest.
CONTACT
Ivan Marazzi (The Rockefeller University, New York, NY, USA)
Tel: +1 212 327 8265; E-mail: [email protected]
Michael Katze (University of Washington, Seattle, WA, USA) N&V author
Tel: +1 206 732 6135; E-mail: [email protected]
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[5] Evolution: Tracing the origins of vertebrate brain complexity (pp 289-294)
Features of a genetic toolkit thought to be unique to brain development in vertebrates, including humans, have been observed in a class of invertebrates and are described in this week’s Nature. The findings reveal an unexpectedly deep origin of these features, which predates vertebrate brains.
The vertebrate brain is complex and has structures that are not seen in our closest invertebrate relatives. Three signalling centres thought to have first assembled in vertebrates are implicated in this complexity. Looking at the genetic programme associated with these signalling centres, Christopher Lowe and colleagues find homologues of vertebrate signalling in the acorn worm, an invertebrate with no brain. From this discovery the authors infer that the genetic programme that leads to the development of highly sophisticated vertebrate brains originated in invertebrates.
The authors suggest that certain classes of invertebrates are more informative when it comes to understanding the origins of vertebrate developmental genetic processes. They recommend further studies of invertebrates to determine how deep the genetic pattern related to vertebrate signalling goes.
CONTACT
Christopher Lowe (Stanford University, Pacific Grove, CA, USA)
Please note this author is travelling and will have limited telephone and e-mail access after 10 March.
Tel: +1 312 520 2927; E-mail: [email protected]
Ariel Pani (Stanford University, Pacific Grove, CA, USA) co-author
Tel: +1 831 655 6227 or: +1 312 608 4126; E-mail: [email protected]
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[6] Synthetic chemistry: Copy catalysts (pp 315-319; N&V)
A new catalyst that may enable synthetic chemists to synthesize drug-like molecules and natural products is described in Nature this week. The phosphorus-containing catalyst can facilitate the formation of a specific three-dimensional orientation of a class of molecules known as spiroacetals, which have previously been difficult to make in the laboratory. These chemicals are found in a broad range of compounds produced by insects, plants, bacteria and marine organisms.
Many natural products display a property called chirality, whereby the molecule can exist in one of two possible mirror image versions of itself; such subtle differences can have a dramatic effect on the biological properties of the molecule. For example, the sex pheromone olean of the olive fruitfly has one mirror image variant that attracts males and the other one attracts females. Ilija Čorić and Benjamin List have overcome challenges in replicating such natural products synthetically by developing a catalyst that can drive the formation of specific chiral variants of several spiroacetals from simpler compounds.
The authors hope that their method will pave the way for the synthesis of a diverse range of natural products and other biologically active molecules.
CONTACT
Benjamin List (Max-Planck-Institut für Kohlenforschung, Mülheim an der Ruhr, Germany)
Tel: +49 208 306 2410; E-mail: [email protected]
Eric Jacobsen (Harvard University, Cambridge, MA, USA) N&V author
Tel: +1 617 496 3688; E-mail: [email protected]
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[7] Materials science: Origami with a twist (pp 311-314)
A study described in Nature this week demonstrates that three-dimensional structures with customizable optical properties can be assembled with precision using a method called DNA origami. The approach may lead to efficient ways of creating materials with desirable properties.
Molecular self-assembly is an attractive way of producing materials with specific properties. Tim Liedl and colleagues use DNA origami (DNA-directed self-assembly of materials) to produce structures that contain metal nanoparticles arranged in nanometre-scale helices. Optical activity can be tailored by tuning the interaction between the precisely arranged nanoparticles, through changes in their relative placement, size or chemical composition. This work establishes DNA origami as a useful tool for guiding the self-assembly of nanoparticles into materials with desired electric or magnetic properties, the authors conclude.
CONTACT
Tim Liedl (Ludwig-Maximilians-Universität, München, Germany)
Tel: +49 89 2180 3725; E-mail: [email protected]
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[8] & [9] Quantum physics: Probing complex materials (pp 302-310; N&V)
Two methods for exploring the unusual electronic properties of exotic materials are described in Nature this week. The papers, from independent groups, report very different approaches to answering the same question ― namely, how to control the properties of a peculiar type of particle known as a Dirac fermion.
The electronic structure of certain solids causes them to exhibit so-called ‘Dirac points’, which lie at the heart of many fascinating phenomena. For example, ingraphene, Dirac points cause electrons to behave like Dirac fermions ― effectively massless particles that travel at the speed of light. In conventional solids, the electronic structure of the material cannot be varied, so it is difficult to see how the properties of Dirac points (and thus Dirac fermions) could be controlled.
Tilman Esslinger and colleagues present one solution ― they create a tunable system of ultracold quantum gases within a honeycomb optical lattice, and use it to simulate condensed matter physics. In particular, they demonstrate moving and merging of Dirac points. The system may provide a means of simulating novel properties of materials that are otherwise difficult to predict, such as the physics of topological insulators. It could also reveal new classes of materials that have not yet been physically realized.
In the second paper, Hari Manoharan and colleagues describe a more direct approach, synthesizing an artificial form of graphene with controllable properties by arranging small molecules in a honeycomb pattern on a conducting substrate using scanning tunnelling microscope manipulation. The system can be tuned by changing the lattice parameters, allowing the study of the properties of Dirac electrons. The authors note that further modifications to the lattice can produce ‘pseudo’ electric and magnetic fields. They suggest that this method could be used to observe unique topological effects in solids.
CONTACT
Tilman Esslinger (ETH Zurich, Switzerland) Author paper [8]
Tel: +41 44 633 2340; E-mail: [email protected]
Hari Manoharan (Stanford University, CA, USA) Author paper [9]
Tel: +1 650 479 6266; E-mail: [email protected]
Markus Greiner (Harvard University, Cambridge, MA, USA) N&V author
Tel: +1 617 595 3811; E-mail: [email protected]
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[10] And finally... Monitoring mice in mazes (AOP)
DOI: 10.1038/nature10918
An experiment combining integrative elements of decision-making and attention with spatial navigation provides insights into an area of the brain involved in such cognitive processing in mice. The observations, reported in Nature, demonstrate how different neuronal sequences can represent different decisions during navigation.
The posterior parietal cortex (PPC) is known to have an important role in cognitive processing, combining such tasks as decision-making, categorization and spatial attention. However, the patterns of neuronal activity that underlie PPC function are poorly understood. To learn more about the role of the PPC in rodents, David Tank and his team imaged this region of the brain in mice performing a virtual maze task. In this task the mice use both decision-making and working memory behaviours to navigate and learn the route.
Tank and colleagues observed neuron activation patterns and found that distinct neuronal sequences represent different decisions during navigation. The authors use these data to characterize how these circuits operate during decision tasks. They suggest a model of PPC function in which activation of choice-specific neurons underlies working memory in a navigational task.
CONTACT
David Tank (Princeton University, NJ, USA)
Tel: +1 609 258 7371; E-mail: [email protected]
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ALSO IN THIS ISSUE…
[11] Goblet cells deliver luminal antigen to CD103+ dendritic cells in the small intestine (pp 345-349)
ADVANCE ONLINE PUBLICATION
[12] Intrinsic coupling of lagging-strand synthesis to chromatin assembly
DOI: 10.1038/nature10895
[13] Visualizing molecular juggling within a B12-dependent methyltransferase complex
DOI: 10.1038/nature10916
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GEOGRAPHICAL LISTING OF AUTHORS…
The following list of places refers to the whereabouts of authors on the papers numbered in this release. For example, London: 4 - this means that on paper number four, there will be at least one author affiliated to an institute or company in London. The listing may be for an author's main affiliation, or for a place where they are working temporarily. Please see the PDF of the paper for full details.
AUSTRALIA
Melbourne: 1
FINLAND
Aalto: 7
Helsinki: 1
GERMANY
Garching: 7
Mülheim an der Ruhr: 6
München: 7
SPAIN
Madrid: 9
SWITZERLAND
Zurich: 8
UNITED KINGDOM
Stevenage: 4
UNITED STATES OF AMERICA
California
Menlo Park: 9, 13
Pacific Grove: 5
Stanford: 9
Illinois
Carbondale: 11
Chicago: 5
Iowa
Iowa City: 3
Maryland
Baltimore: 13
Massachusetts
Boston: 10
Cambridge: 2, 13
Michigan
Ann Arbor: 13
Missouri
St. Louis: 11
Nebraska
Lincoln: 13
New Jersey
Princeton: 10
New York
New York: 4, 12
Palisades: 2
Ohio
Athens: 7
Washington
Seattle: 1, 3
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From Japan, Korea, China, Singapore and Taiwan
Eiji Matsuda, Nature Tokyo
Tel: +81 3 3267 8751; E-mail: [email protected]
From the UK
Rebecca Walton, Nature London
Tel: +44 20 7843 4502; E-mail: [email protected]
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