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This press release is copyright Nature.
VOL.463 NO.7279 DATED 20 JANUARY 2010
This press release contains:
· Summaries of newsworthy papers:
Biodiversity: Ocean currents carried mammals to Madagascar
Synthetic biology: Making waves
Air pollution: Counting the cost of Asian emissions
Neuroscience: Grid power
Opinion: Two takes on building consensus about science
Materials: A mouldable, self-healing clay-based hydrogel
Materials science: Size matters in deformation twinning
And finally…Meteorites: Solving the colour conundrum
· Mention of papers to be published at the same time with the same embargo
· Geographical listing of authors
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[1] Biodiversity: Ocean currents carried mammals to Madagascar
DOI: 10.1038/nature08706
***This paper will be published electronically on Nature's website on 20 January 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 21 January, but at a later date. ***
Favourable ocean currents transported the ancestors of Madagascar’s mammals to the island around 50 million years ago, a Nature study suggests.
Madagascar plays host to some of the world’s most unique, diverse and threatened animals, but how they got there remains a mystery. This modelling study, by Jason Ali and Matthew Huber, suggests that, for a few million years during the Palaeogene period, strong surface currents flowed from northeast Mozambique and Tanzania eastward towards Madagascar.
The results back up a 70-year-old hypothesis that proposes animals arrived by raft, and contradicts the view that currents flowed the wrong way for successful rafting and that animals walked to Madagascar on land bridges.
CONTACT
Matthew Huber (Purdue University, West Lafayette, IN, USA)
Tel: +1 465 494 0652; E-mail: [email protected]
[2] Synthetic biology: Making waves (pp 326-330; N&V)
Researchers have built populations of Escherichia coli cells that fluoresce in synchrony or produce waves of luminescence. The ability to build such synthetic systems could help future research on more complex natural processes such as rhythmic insulin secretion and circadian rhythms.
The engineering of genetic circuits with predictive functionality in living cells has been a focus of synthetic biology. This was set in motion a decade ago with the design and construction of a genetic toggle switch and an oscillator. In this week’s Nature Jeff Hasty and colleagues report that they have derived general rules about factors controlling coherent behaviours in populations of genetically engineered bacteria.
The team used computer modelling to predict the period and amplitude of the synchronized oscillations in gene expression. The work provides a specific model system for the mechanistic description of coordinated behaviour at the multicellular level.
CONTACT
Jeff Hasty (University of California San Diego, La Jolla, CA, USA)
Tel: +1 858 822 3442; E-mail: [email protected]
Martin Fussenegger (ETH Zürich, Switzerland) N&V Author
E-mail: [email protected]
[3] Air pollution: Counting the cost of Asian emissions (pp 344-348; N&V)
Western North America is sensitive to rising Asian pollutant emissions, reports a Nature paper. Increasing ozone levels in the air may make it more difficult for the USA to meet its own ozone air quality standard.
Ozone in the Earth’s upper atmosphere filters harmful ultraviolet rays, but when found in the lower atmosphere, the troposphere, it can act as a toxic gas — causing respiratory illnesses and affecting ecosystems. Industrial emissions have caused widespread increases in ozone levels since the 1800s, and today east Asia has the fastest-growing emissions in the world. Scientists have long speculated that ozone levels in the free troposphere above western USA may rise in response to increased Asian pollutant output, but no previous studies have firmly supported this idea since measurements began in the late 1970s.
Owen Cooper and colleagues compiled ozone measurements from many different platforms across western North America and discovered a strong increase in springtime ozone mixing ratios from 1995 to 2008.The rate of increase in ozone mixing ratio is greatest when measurements are more heavily influenced by direct transport from Asia. They suggest that the observed increase in ozone may hinder the USA's compliance with its ozone air quality standard.
CONTACT
Owen Cooper (University of Colorado, Boulder, CO, USA)
Tel: +1 303 497 3599; E-mail: [email protected]
Kathy Law (Universite Paris VI, France) N&V Author
Tel: +1 33 1 4427 8421; E-mail: [email protected]
[4] Neuroscience: Grid power
DOI: 10.1038/nature08704
***This paper will be published electronically on Nature's website on 20 January 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 21 January, but at a later date. ***
Human brains may possess grid cells — specialized neurons so far only found in rodent brains and thought to be involved in spatial memory. The discovery, reported in this week's Nature, may help to explain how we create internal maps of new environments.
Grid cells are so called because, when a rat moves around on a flat surface, they fire in patterns that show up as geometrically regular, triangular grids when plotted on a map of the surface. Their discovery some years ago suggested that rats might create virtual grids to help them orient themselves in their surroundings, and remember new locations in unfamiliar territory.
Christian Doeller and colleagues combined electrophysiological recordings of single grid cells in freely moving rats with functional MRI (fMRI) recordings of humans navigating virtual environments, and found fMRI signals that met the criteria for grid-cell encoding. The signals emanated from brain regions known to be involved in imagery and autobiographical memory, so the authors speculate that grid cells may encode temporal as well as spatial context.
CONTACT
Christian Doeller (University College London, UK)
Tel: +44 207 679 1146; E-mail: [email protected]
Opinion: Two takes on building consensus about science
We need to use better techniques to harvest expert advice on risk and uncertainty, and better techniques to communicate it. That’s the message of two Opinion pieces in this week’s Nature.
When politicians and other decision-makers seek advice from experts, they usually hope to receive something unambiguous that they can act on. But as risk consultant Willy Aspinall explains, in complex situations — assessing the risk of volcanic eruptions and earthquakes for instance — attempts to force a consensus can be counterproductive. It is better to quantify the uncertainty that exists and build it into the decision-making process. The way to do this, says Aspinall, is through ‘expert elicitation’, specifically by using a method developed by Roger Cooke, which weighs the opinion of each expert based on his or her knowledge and ability to judge relevant uncertainties. Indeed some people have called for the Intergovernmental Panel on Climate Change to use such methods.
Meanwhile, Daniel Kahan urges the science-communication community to take note of recent research showing how much a person’s cultural worldview — how they value concepts such as equality, authority, individualism and collectivism — shapes how they accept and reject information about risks. He presents findings illustrating how perceptions about the messenger, as much as the message, can influence people’s thinking about issues such as climate change, vaccinations and nuclear energy. He suggests how to present information so it is agreeable to culturally diverse groups, and how to structure debate so that it avoids cultural polarization.
CONTACT
Willy Aspinall (Bristol University, UK)
Tel: +44 1747 871002; E-mail: [email protected].
Dan Kahan (Yale Law School, New Haven, CT, USA)
E-mail: [email protected]
[5] Materials: A mouldable, self-healing clay-based hydrogel (pp 339-343)
A new type of mouldable water-based gel that self-heals when damaged is reported in this week’s Nature. It’s hoped that the material will aid the design of environmentally friendly alternatives to petroleum-dependent plastics.
The transparent hydrogel, designed by Takuzo Aida and colleagues, is made by mixing water and clay with a small amount of organic components. The resilient gel can be moulded into free-standing objects that retain their shape, and quickly self-heal when damaged. Freshly cut surfaces also stick together, enabling the construction of more complex shapes.
The hydrogel shows that water-based materials held together by non-covalent bonds can be mechanically tough, and may provide many interesting applications. Because it is water-based it could incorporate and maintain biologically active proteins. Connecting together blocks with different enzymatic activities could be used to produce particular reaction sequences.
CONTACT
Takuzo Aida (The University of Tokyo, Japan)
Tel: +81 3 5841 7251; E-mail: [email protected]
[6] Materials science: Size matters in deformation twinning (pp 335-338)
Microscopic measurements of metallic single crystals undergoing compression have yielded new insight into the ways in which these crystals deform, and the dependence of their strength and deformation mechanism on crystal size. The results, reported in this week’s Nature, will have implications for the use of micrometre-scale metal and ceramic components in mechanical applications.
At room temperature, two main processes account for the deformation of crystalline materials: ordinary dislocation plasticity and deformation twinning. In the former, uncorrelated defects in the crystal lattice appear and migrate through the material, allowing the material to deform. By contrast, deformation twinning is a coherent process, in which small regions of the crystal adopt a different orientation of the crystal lattice, which is a mirror image (‘twin’) of the normal structure. The strength of a material deforming by ordinary dislocation plasticity is well known to be dependent on the crystal size, but nothing was known about the size dependence of deformation twinning.
Ju Li and colleagues subjected tiny single crystals of a titanium alloy to compression, and followed the resulting deformation using transmission electron microscopy. They find that the stress required for deformation twinning increases dramatically with decreasing sample size, until, for crystals smaller than one micrometre, the deformation mechanism changes to ordinary dislocation plasticity. The authors present a model of deformation twinning, which helps to explain the size dependence of both strength and mechanism.
CONTACT
Ju Li (University of Pennsylvania, Philadelphia, PA, USA)
Tel: +1 215 898 1558; E-mail: [email protected]
[7] And finally…Meteorites: Solving the colour conundrum (pp 331-334; N&V)
Scientists have discovered why meteorites that land on the Earth don’t often match the ‘colour’ of asteroids orbiting close by. A paper in Nature this week suggests that seismic shaking affects small bodies that pass close to the Earth, revealing fresh, unweathered material on their surfaces.
For several decades, astronomers have wondered why hardly any meteorites that land on the Earth match the telescopic observations of asteroids orbiting in space. It is now known that the space environment rapidly reddens or ‘weathers’ the surfaces of asteroids, but what is not clear is why the relatively few ‘fresh’ asteroids are only seen among small bodies whose orbits cross inside those of Mars and the Earth.
Richard Binzel and colleagues combine spectroscopic data with orbital histories to show that unweathered surfaces are found only among those objects which have passed by the Earth at least as close as the lunar distance in the last 500,000 years. In addition, there are no unweathered bodies among asteroids that have had no recent close planetary encounters. They conclude that tidal stress arising from a close encounter with Earth is most probably the dominant short-term asteroid resurfacing process.
CONTACT
Richard Binzel (Massachusetts Institute of Technology, Cambridge, MA, USA)
Tel: +1 617 253 6486; E-mail: [email protected]
Clark Chapman (Southwest Research Institute, Boulder, CO, USA) N&V Author
Tel: +1 303 546 9670; E-mail: [email protected]
ALSO IN THIS ISSUE…
[8] Mutational robustness can facilitate adaptation (pp 353-355)
DOI: 10.1038/nature08694
[9] FOXO-dependent regulation of innate immune homeostasis (pp 369-373)
DOI: 10.1038/nature08698
[10] Transcriptional role of cyclin D1 in development revealed by a genetic–proteomic screen (pp 374-378)
DOI: 10.1038/nature08684
[11] Mechanism of folding chamber closure in a group II chaperonin (pp 379-383)
DOI: 10.1038/nature08701
ADVANCE ONLINE PUBLICATION
***These papers will be published electronically on Nature's website on 20 January 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 them on this release to avoid multiple mailings they will not appear in print on 21 January, but at a later date. ***
[12] Competition drives cooperation among closely related sperm of deer mice
DOI: 10.1038/nature08736
[13] Mechanism of substrate recognition and transport by an amino acid antiporter
DOI: 10.1038/nature08741
********************************************************************
***The following paper was published electronically on Nature’s website on 14 January at 1800 London time / 1300 US Eastern time. The paper is therefore no longer under embargo. The rest of the above articles on this release remain under embargo until 20 January at 1800 London time / 1300 US Eastern time ***
[14] JARID2 regulates binding of the Polycomb Repressive Complex 2 to target genes in ES cells
DOI: 10.1038/nature08788
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.
CANADA
Downsview: 3
CHINA
Beijing: 13
Hong Kong: 1
Shandong: 13
Xian: 6
DENMARK
Copenhagen: 14
Roskilde: 6
FRANCE
Meudon: 7
Nice: 7
Paris: 7
Toulouse: 3
GERMANY
Bonn: 9
Julich: 11
Marburg: 11
ITALY
Milan: 14
JAPAN
Ibaraki: 5
Tokyo: 5
NETHERLANDS
Noordwijk: 7
NORWAY
Kjeller: 3
SOUTH KOREA
Seoul: 5
THAILAND
Nakhon Prathom: 10
UNITED KINGDOM
Cambridge: 10
Edinburgh: 14
London: 4
UNITED STATES OF AMERICA
Arizona
Flagstaff: 7
California
La Jolla: 2
Stanford: 10, 11
Wrightwood: 3
Colorado
Boulder: 3
Broomfield: 3
Connecticut
New Haven: 8
Hawaii
Hilo: 7
Indiana
West Lafayette: 1
Maryland
Baltimore: 6
Laurel: 7
Massachusetts
Boston: 10
Cambridge: 7, 10, 12
Minnesota
Minneapolis: 6
Pennsylvania
Philadelphia: 6, 8
Texas
Houston: 11
Virginia
Hampton: 3
Washington
Bothell: 3
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
Rachel Twinn, Nature, London
Tel: +44 20 7843 4658; E-mail: [email protected]
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