This press release contains:
Astrophysics: Sagittarius impact on Milky Way morphology
Synthetic biology: Yeast, but not as we know it
Ecology: Root of the forest biodiversity problem
Geoscience: Linking mantle plumes with environmental catastrophes
Astrophysics: Delving into Delta Scuti stars
Physics: Silicon shapes-up magnetoelectronics
Chemistry: Long, strong carbon-carbon bonds
Ecology: Similarities between ecological and economic networks
And finally… Pride doesn’t always come before a fall
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[1] Astrophysics: Sagittarius impact on Milky Way morphology (pp 301-303; N&V)
Simulations of the response of the Milky Way to the infall of the Sagittarius dwarf galaxy (Sgr) presented in Nature this week suggest that minor mergers of galaxies with a smaller companion have an important role in shaping galactic structure.
Traditional attempts to understand the Milky Way’s disk shape, with prominent spiral arms rooted in a central bar, assume that it has been unperturbed by major external forces. However, Chris Purcell and colleagues use simulation models to discern the effect of the Sgr impact on the Galactic disk. Infall of the Sgr results in the formation of spiral arms, influences the central bar and produces a flared outer disk. In their model two arcs are produced, one of which resembles a low-latitude feature of the Milky Way known as the Monoceros ring.
These results show that the Milky Way's morphology is not purely secular in origin and that its evolution has also been affected by external processes.
CONTACT
Chris Purcell (The University of Pittsburgh, PA, USA)
Tel: +1 949 232 9273; E-mail: [email protected]
Curtis Struck (Iowa State University, Ames, IA, USA) N&V author
Tel: +1 515 294 3666; E-mail: [email protected]
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[2] Synthetic biology: Yeast, but not as we know it (AOP)
DOI: 10.1038/nature10403
The production of partially synthetic yeast chromosomes reported in this week’s Nature represents a step towards the design and construction of an entirely synthetic version of the yeast genome. Synthetic yeast will be an invaluable tool for studies to improve our understanding of eukaryotic genomics. Moreover, the approach can be used to introduce genetic diversity, which will be useful in selection experiments.
Jef Boeke and colleagues produced a synthetic chromosome arm based on a native sequence in Saccharomyces cerevisiae. Included in this arm is an in-built customizable evolution system called SCRaMbLE that allows the introduction of mutations, giving rise to a broad variety of genotypes and phenotypes. The study represents a proof of principle for creating entire synthetic genomes. SCRaMbLE could be a useful tool for producing genetic diversity and for analysing genome structure, content and function, the authors propose.
CONTACT
Jef Boeke (Johns Hopkins University, Baltimore, MD, USA)
Tel: +1 410 955 0398; E-mail: [email protected]
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[3] Ecology: Root of the forest biodiversity problem (AOP)
DOI: 10.1038/nature10425
Primary forests are irreplaceable when it comes to maintaining tropical biodiversity, a meta-analysis published in Nature this week shows. Most forms of forest degradation have an overwhelmingly detrimental effect on tropical biodiversity, and secondary forests are poor substitutes for primary forests.
Primary tropical forests with little or no human disturbance are diminishing due to conversion and degradation by human activities and in many locations, they have been replaced by agriculture, plantations and secondary forests. Luke Gibson and co-workers conduct a global meta-analysis of 138 studies to measure the varied effects of land-use change and forest degradation on biodiversity in tropical forests. They find that the extent to which biodiversity is reduced varies by geographic region, taxonomic group, disturbance type and the metric used to measure biodiversity (abundance and richness are the most commonly reported, of which richness is more sensitive to human disturbance). With the possible exception of selective logging, all land-use changes from primary forest lead to substantial decreases in biodiversity.
Some research has suggested that secondary forests can be an effective complement to primary forests in supporting tropical forest biodiversity. However, Gibson and colleagues find that secondary forests are a poor substitute and strongly urge the protection of primary forests.
CONTACT
Luke Gibson (National University of Singapore, Singapore)
Tel: +65 9018 6575; E-mail: [email protected]
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[4] Geoscience: Linking mantle plumes with environmental catastrophes (pp 312-316; N&V)
A model of the formation of the Siberian Traps large igneous province, which is associated with the largest-known mass-extinction event, is presented in Nature this week. The findings may help to explain why extinctions happened before, not during, the main volcanic phase.
Mantle plumes and large igneous provinces, where large volumes of magma are generated, have been linked to global environmental catastrophes. However, research suggests that extinctions occurred before the main phase of volcanism. Stephan Sobolev and colleagues present evidence from a thermomechanical model that may solve this conundrum. The model indicates that a massive release of CO2 and HCI occurs before the main volcanic phase and could be solely responsible for triggering a mass extinction.
The authors present petrological data indicating that a large amount of recycled oceanic crust was present in the head of the plume that was responsible for forming the Siberian Traps large igneous province. Their modelling shows that such dense material would reduce the amount of uplift by reducing the plume buoyancy, thus also explaining the lack of observed uplift both at the Siberian Traps and some other large igneous provinces.
CONTACT
Stephan Sobolev (Deutsches GeoForschungsZentrum GFZ, Potsdam, Germany)
Tel: +49 331 288 1940; E-mail: [email protected]
Paul Wignall (University of Leeds, UK) N&V author
Tel: +44 113 3435247; E-mail: [email protected]
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[5] Astrophysics: Delving into Delta Scuti stars (AOP)
DOI: 10.1038/nature10389
*** This paper will be published electronically on Nature's website on 14 September at 1800 London time / 1300 US Eastern Time (which is also when the embargo lifts) as part of our AOP (ahead of print) programme. Although we have included it on this release to avoid multiple mailings it will not appear in print on 15 September, but at a later date. ***
Observations of the oscillations of a Delta Scuti star reported in Nature this week suggest that surface convection operates efficiently in stars about twice as massive as the Sun. The findings may allow a better understanding of the interiors of distant stars.
Stars of the Delta Scuti type are pulsators — sometimes known as dwarf Cepheids — in which the varying ionization of helium is responsible for the pulsations. Ad hoc models predict that the convective envelope in these stars extends only to about one per cent of the radius, but with sufficient energy to excite solar-like oscillations, which until now have not been observed. Victoria Antoci and colleagues report the detection of solar-like oscillations in the Delta Scuti star HD 187547. From these observations, the authors derive the depth of the convective envelope, probing the diffusion of helium and heavy elements in HD 187547.
The findings may help to revise models predicting the interaction between pulsation and diffusion in such stars.
CONTACT
Victoria Antoci (University of Vienna, Austria)
Tel: +43 1 4277 51822; E-mail: [email protected]
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[6] Physics: Silicon shapes-up magnetoelectronics (pp 304-307)
Silicon semiconductors with enhanced sensitivities that could prove attractive to the magnetic-field sensing industry are described in Nature this week. The shape of these devices can be exploited to enhance their performance to levels achieved by commercial giant-magnetoresistance devices.
Some non-magnetic semiconductors, including silicon, exhibit potentially useful electrical responses to magnetic fields (an effect called inhomogeneity-induced magnetoresistance). This form of magnetoresistance is thought to be influenced by spatial variations of the conductivity in the material. Xiaozhong Zhang and colleagues show that this effect can be engineered and enhanced in silicon via the geometry of the device. Their device is versatile as it displays enhanced sensitivities to both high and low magnetic fields and is compatible with mature silicon technology.
Moreover, the authors suggest that as the device can be modified by both electric and magnetic fields, it could aid the development of silicon-based magnetoelectronics.
CONTACT
Xiaozhong Zhang (Tsinghua University, Beijing, China)
Tel: +86 10 6277 3999; E-mail: [email protected]
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[7] Chemistry: Long, strong carbon-carbon bonds (pp 308-311)
The synthesis of hydrocarbon compounds with surprisingly stable long carbon-carbon (C–C) bonds is reported in Nature this week. The findings may help to understand the nature of intramolecular forces and provide a new method for overcoming bond weakening caused by repulsive interactions.
The strengths of chemical bonds depend on the balance between attractive and repulsive forces between groups around the bonds. Generally, C–C bonds tend to get weaker the longer they are. However, Peter Schreiner and colleagues report an example that bucks this trend. The researchers coupled rigid diamond-like molecules to create alkane hydrocarbons that contain the longest C–C bond observed in this group of compounds. Remarkably, the authors find that weak attractive dispersion forces between bulky groups at the ends of C–C bonds overcome the repulsive forces in the molecules, making the compounds unexpectedly stable.
The stabilizing interactions observed in this work could have important consequences in the development of new materials that use attractive dispersion interactions.
CONTACT
Peter Schreiner (Justus-Liebig-Universität, Giessen, Germany)
Tel: +49 641 99 34300; E-mail: [email protected]
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[8] Ecology: Similarities between ecological and economic networks (AOP)
DOI: 10.1038/nature10433
A study that draws parallel conclusions about the roles and outcomes of individual nodes in both ecological and socio-economic mutualistic networks is published in Nature this week. The results show that nodes that improve network stability do not reap the benefits and are the most likely to be wiped out.
Jordi Bascompte and colleagues quantify the contribution of a node to the overall network architecture and determine how this contribution relates to the node’s dynamic survival. In flowering plant/pollinating insect networks, nodes that contribute to the nestedness of the network provide stability; removal of these strong nodes has a greater detrimental effect on the network than removal of weaker nodes. Moreover, strong nodes do not gain individual survival benefits the more they contribute, but are in fact the nodes most vulnerable to extinction.
The researchers observe similar outcomes in a mutualistic network of designer firms and their contractors in the New York City garment industry: a firm’s survival probability decreases as its individual nestedness contribution increases. These findings could address questions about the impact of invasive species in ecological systems and new competitors in economic systems, the authors suggest.
CONTACT
Jordi Bascompte (Estación Biológica de Doñana, Seville, Spain)
Tel: +34 954 466 700; E-mail: [email protected]
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[9] And finally… Pride doesn’t always come before a fall (pp 317-320; N&V)
Overconfidence is often blamed for its role in financial collapses, policy failures, disasters and costly wars, but an evolutionary modelling study published in Nature this week suggests that in certain well-defined circumstances, it can be a beneficial trait.
Overconfidence, which leads people to overestimate their own abilities and/or underestimate an opponent or the difficulty of a task, has remained a major puzzle in evolutionary biology, economics and political science because despite causing costly decision-making errors, it remains a widespread psychological bias. Previous research has suggested that overconfidence may be advantageous because it increases ambition, resolve or persistence, but this theory hasn’t been formally tested.
Dominic Johnson and James Fowler used game theory to model situations in which overconfidence confers higher evolutionary fitness than unbiased strategies. They found that under certain well-specified conditions, overconfidence increases average individual fitness, as long as the rewards or benefits at stake sufficiently outweigh the costs of competing for them.
These adaptive advantages of overconfidence may explain its emergence and spread in humans and other animals. But although overconfidence may have been adaptive in our past and may still be beneficial in some settings today, it seems that people are likely to become overconfident in precisely the riskiest situations.
CONTACT
Dominic Johnson (University of Edinburgh, UK)
Tel: +44 131 650 3937 ; E-mail: [email protected]
Martin Nowak (Harvard University, Cambridge, MA, USA) N&V author
Tel: +1 617 496 4737; E-mail: [email protected]
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ALSO IN THIS ISSUE…
[10] Mouse genomic variation and its effect on phenotypes and gene regulation (pp 289-294)
[11] Sequence based characterization of structural variation in the mouse genome (pp 326-329)
[12] Caspase-8 regulates TNF-alpha-induced epithelial necroptosis and terminal ileitis (pp 335-339
ADVANCE ONLINE PUBLICATION
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[13] The NLRC4 inflammasome receptors for bacterial flagellin and type III secretion apparatus
DOI: 10.1038/nature10510
PICTURES: While we are happy for images from Nature to be reproduced for the purposes of contemporaneous news reporting, you must also seek permission from the copyright holder (if named) or author of the research paper in question (if not).
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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
Adelaide: 3
Cairns: 3
Henley Beach: 3
Sydney: 5
AUSTRIA
Vienna: 5
BELGIUM
Brussels: 5
Leuven: 5
BRAZIL
Manaus: 3
CANADA
Vancouver: 5
CHINA
Beijing: 2, 6, 13
DENMARK
Aarhus: 5
FRANCE
Gif-sur-Yvette: 5
Grenoble: 4
GERMANY
Erlangen: 12
Freiburg: 5
Giessen: 7
Mainz: 4, 12
Potsdam: 4
Stralsund: 10, 11
ITALY
Catania: 5
NEW ZEALAND
Christchurch: 8
POLAND
Warsaw: 5
PORTUGAL
Porto: 5
RUSSIA
Moscow: 4
Norilsk: 4
Novosibirsk: 4
SINGAPORE
Singapore: 3
SPAIN
Madrid: 5
Santa Cruz de Tenerife: 5
Seville 8
Tenerife: 5
SWITZERLAND
Zurich: 3
UKRAINE
Kiev: 7
UNITED KINGDOM
Cambridge: 3
Edinburgh: 9, 10
Hinxton: 10, 11
Lancaster: 3
Norwich: 3
Oxford: 10, 11
Preston: 5
UNITED STATES OF AMERICA
California
Irvine: 1
La Jolla: 3, 12
Los Angeles: 10
Moffett Field: 5
San Diego: 9
Stanford: 7
Connecticut
New Haven: 3
District of Columbia
Washington: 3
Florida
Boca Raton: 1
Georgia
Atlanta: 2
Illinois
Chicago: 8
Evanston: 8
Maine
Bar Harbor: 10
Brunswick: 2
Maryland
Baltimore: 2
Massachusetts
Cambridge: 2
Medford: 2
Pennsylvania
Pittsburgh: 1
Washington
Seattle: 2
Wisconsin
Madison: 10
PRESS CONTACTS…
From North America and Canada
Neda Afsarmanesh, Nature New York
Tel: +1 212 726 9231; E-mail: [email protected]
From Japan, Korea, China, Singapore and Taiwan
Mika Nakano, 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]
