The last straw for the first bird?

This press release contains:

• Summaries of newsworthy papers:

Fossils: The last straw for the first bird?
Planetary science: Earth's Trojan companion
Neuroscience: Bringing back memory
Neuroscience: Tipping the balance
Solar physics: Wave power
Climate change: Substantial carbon release from burning Arctic tundra
Earth science: An ancient source for flood basalts
Cancer: Unexpected role for histones in non-Hodgkin’s lymphoma
And finally... Thanks be to cod!

• Mention of papers to be published at the same time
• Geographical listing of authors

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[1] Fossils: The last straw for the first bird? (pp 465-470; N&V)

The discovery of a fossil representing a previously unknown species of bird-like dinosaur from the Late Jurassic of China could represent the final straw in the theory that the iconic fossil Archaeopteryx is the earliest and most primitive bird. The findings are reported this week in Nature, 150 years after the discovery of Archaeopteryx.

Archaeopteryx has long been accepted as the earliest known bird and has been regarded as central to the scientific understanding of the evolution of birds and of flight. But its position has weakened over the past 15 years thanks to the discovery of a number of feathered, bird-like dinosaurs. Xing Xu and colleagues describe the fossilized remains of a small, feathered, Archaeopteryx-like dinosaur, weighing about 0.8 kg.

The discovery of the new theropod shows that several features, including long, robust forearms, that were thought to be distinctive of avialans (a group containing the ancestors of modern birds) but may actually be characteristic of the more inclusive clade of paravians, which comprises the avialans and a group of theropods called deinonychosaurs.

The phylogenetic analysis, which is the first to remove Archaeopteryx from the avialans, is tentative but if it can be confirmed by further investigation, current assumptions about the ancestry of modern birds will need to be re-evaluated.

CONTACT
Xing Xu (Chinese Academy of Sciences, Beijing, China)
Tel: +86 10 8836 9196; E-mail: [email protected]

Lawrence Witmer (Ohio University, Athens, OH, USA) N&V author
Tel: +1 740 593 9489; E-mail: [email protected]

[2] Planetary science: Earth's Trojan companion (pp 481-483)

A small asteroid has been found accompanying the Earth in its journey around the Sun, in a stable ‘Trojan’ orbit. With this discovery, reported in this week’s Nature, the Earth joins Jupiter, Mars and Neptune in the list of planets with known Trojan companions.

Trojan companions are able to co-orbit stably with a planet by remaining near one of the ‘triangular points’, 60° ahead of or behind the planet in its orbit. The existence of Trojan asteroids accompanying other planets raised the question of whether the Earth also had such companions, but their orbit would keep them mostly in the daylight sky, making them difficult to detect.

As Martin Connors and colleagues now report, the launch of the Wide-field Infrared Survey Explorer satellite in 2009 provided improved viewing capabilities, leading to the detection of more than 500 near-Earth objects. By examining the orbits of these objects, the authors identified one called 2010 TK7 as a probable Earth Trojan, and then confirmed this conclusion using optical observations from ground-based telescopes. 2010 TK7 appears to be about 300 metres in diameter, and is leading the Earth in its orbit; the authors compute that its orbit is stable over at least 10,000 years.

CONTACT
Martin Connors (Athabasca University, Athabasca, Canada)
Tel: +1 780 800 5438; E-mail: [email protected]

[3] Neuroscience: Bringing back memory (AOP)
DOI: 10.1038/nature10243

*** This paper will be published electronically on Nature's website on 27 July 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 28 July, but at a later date. ***

Aged monkeys lack the normal persistent firing of neurons in the prefrontal cortex (PFC) — an area of the brain that is critical to working memory. As reported in Nature this week, diminished firing levels can be rescued by restoring the PFC to an optimal neurochemical environment found in younger monkeys. This demonstrates that the physiological integrity of aged neurons can be rescued by addressing the molecular needs of circuits.

Working memory is critical to everyday tasks, including planning ahead and learning. Early on in normal aging, PFC function declines, leading to cognitive deficits such as forgetfulness and distractibility. However, the molecular changes associated with this normal aging process were not known.

To characterize physiological changes in the PFC, Amy Arnsten and colleagues performed in vivo recordings of six young-adult, middle-aged and aged monkeys while they performed short-term memory tasks. They found that the firing pattern of PFC neurons responding to cue presentation did not change with age.

However, the neurons that fire during a delay period — the time between a cue being presented and an action or response being made — showed significant decline with age. These neurons could be partially restored to young-adult levels of firing when Arnsten and colleagues blocked two specific channels on PFC neurons.

CONTACT
Amy Arnsten (Yale University School of Medicine, New Haven, CT, USA)
Tel: +1 203 785 4431; E-mail: [email protected]

[4] Neuroscience: Tipping the balance (AOP)
DOI: 10.1038/nature10360

*** This paper will be published electronically on Nature's website on 27 July 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 28 July, but at a later date. ***

Two optogenetic tools, which use light to control neuronal activity and that can be used to study the role of cellular imbalances in certain psychiatric diseases, are reported in Nature this week.
According to one theory, the cellular disturbances that underlie the social and cognitive deficits in disorders such as autism and schizophrenia are caused by an imbalance of excitatory and inhibitory activity in neurons, for example in the pre-frontal cortex (PFC) region. This imbalance is thought to affect how these cells process information but the model has proved difficult to test.
Karl Deisseroth and colleagues describe two optogenetic tools that can be used to selectively control two intermingled populations of neurons. The authors use these tools to show that disrupting the cellular excitation/inhibition balance by increasing relative excitation in the mouse PFC impairs social and learning behaviours. When the imbalance is redressed, by increasing the level of inhibitory cell activity, the social deficits are partially restored. These effects are instantaneous and reversible.
The study highlights the potential of optogenetics for unravelling the complex neuronal circuitry underlying psychiatric disease.

CONTACT
Karl Deisseroth (Stanford University, CA, USA)
Tel: +1 650 736 4325; E-mail: [email protected]

[5] Solar physics: Wave power (477-480; N&V)

Magnetic oscillations travelling upwards through the Sun’s outer atmosphere have enough energy to heat its quiet portions, and to accelerate the fast solar wind, according to a paper in this week’s Nature.

The Sun’s outer atmosphere, or corona, has a temperature of millions of degrees, and gives rise to streams of charged particles (the solar wind) travelling at hundreds of kilometres per second. All this requires energy, and travelling magnetic waves known as Alfvén waves have been proposed as a way of transporting energy upwards into the corona. Until now, however, evidence has been lacking for Alfvénic waves in sufficient abundance and with large enough amplitude to supply the necessary energy flux.

Scott McIntosh and colleagues now provide such evidence, in the form of satellite images of the corona and its underlying transition region at extreme ultraviolet wavelengths. The authors find that upward-travelling Alfvénic waves are ubiquitous in the corona, supplying energy to the region at rates of 100–200 watts per square metre. This is sufficient to drive the fast solar wind, and to heat the quiet corona, but seems insufficient to account for the intense emissions of radiation in the corona’s active regions.

CONTACT
Scott McIntosh (National Center for Atmospheric Research, Boulder, CO, USA)
Tel: +1 303 497 1544; E-mail: [email protected]

Peter Cargill (Imperial College London, UK) N&V author
E-mail: [email protected]

[6] Climate change: Substantial carbon release from burning Arctic tundra (pp 489-492)

As the climate warms, fire activity in Arctic tundra regions has been increasing, and a recent fire in Alaska reached an unprecedented size. A field study from the burn scar, reported in this week’s Nature, reveals that large amounts of carbon stored in the soil were released in the process.

Arctic tundra landscapes store large amounts of carbon in organic-rich soil layers, which also insulate underlying permafrost soils. In boreal and temperate ecosystems, organic soils can be highly flammable, and may burn deeply, releasing large amounts of carbon. But little has been known about the effect of fire on the carbon balance of tundra landscapes — a knowledge gap that needs to be filled, because the incidence of tundra fires has increased in recent years.

Michelle Mack and colleagues report measurements of carbon loss from an Alaskan Arctic wildfire in 2007, which burned an area equal to the total that had been burned since 1950. The authors find that about 2.1 teragrams of carbon was released to the atmosphere — an amount similar to the net amount of carbon absorbed each year by the entire Arctic tundra biome.

The results show how a single fire can rapidly change the net carbon balance of the tundra, and provide a mechanism for amplification of climate warming.

CONTACT
Michelle Mack (University of Florida, Gainesville, FL, USA)
Tel: +1 352 846 2510; E-mail: [email protected]

[7] Earth science: An ancient source for flood basalts (AOP)
DOI: 10.1038/nature10326

*** This paper will be published electronically on Nature's website on 27 July 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 28 July, but at a later date. ***

Several of the largest volcanic events in the Earth’s history seem to have tapped a part of the Earth’s mantle that has remained largely isolated throughout geological time, according to a study published online this week in Nature. The geochemical characteristics of this ancient mantle source may also explain the extraordinarily large volumes of melt produced in these events.

Large outpourings of lava known as flood basalts, or ‘large igneous provinces’, have occurred throughout the Earth’s history, but their origins are not well understood. Last year, a geochemical study of flood basalts erupted 62 million years ago in Baffin Island and West Greenland (Nature 466, 853–856) suggested that they had come from a part of the Earth’s mantle that had remained isolated for about 4.5 billion years.

Now, two of the authors of the earlier study, Matthew Jackson and Richard Carlson, have examined the geochemistry of basalts from five additional large igneous provinces, including the largest volcanic event in geological history, the Ontong–Java Plateau. They find that these basalts, with ages ranging back to 250 million years ago, also exhibit the geochemical signatures of the ancient mantle reservoir.

The authors suggest that the higher concentration of heat-producing elements in this primitive mantle, and its more ‘fertile’ composition, may combine to account for the huge volumes of melt seen in large igneous provinces.

CONTACT
Matthew Jackson (Boston University, MA, USA)
Tel: +1 617 358 5891; E-mail: [email protected]

[8] Cancer: Unexpected role for histones in non-Hodgkin’s lymphoma (AOP)
DOI: 10.1038/nature10351

*** This paper will be published electronically on Nature's website on 27 July 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 28 July, but at a later date. ***

Histone-modifying genes are frequently mutated in non-Hodgkin’s lymphoma (NHL), suggests a paper published online in Nature.
Histone proteins act as spools for nuclear DNA to wrap around, and their modification is known to influence gene expression. In their study, Marco Marra and colleagues highlight 109 genes frequently mutated in NHL, most of which were not considered ‘cancer genes’ before. These include genes that alter histone structure, adding or removing various chemical groups.

The study focuses on the two most common NHLs, diffuse large B-cell lymphoma and follicular lymphoma and it suggests that mutated genes causing reduced acetylation and enhanced methylation of histones probably contributes to the development of NHL.

CONTACT
Marco Marra (BC Cancer Agency, Vancouver, Canada)
Tel: +1 604 675 8168; E-mail: [email protected]

[9] And finally... Thanks be to cod! (AOP)
DOI: 10.1038/nature10285

*** This paper will be published electronically on Nature's website on 27 July 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 28 July, but at a later date. ***

The over-fished cod stocks of the northwest Atlantic may yet recover, a Nature paper suggests.

Over-fishing of big, seabed-dwelling fish on the Scotian Shelf of Canada’s east coast triggered dramatic and widespread population collapses that have failed to recover despite a fishing moratorium lasting almost 20 years. Kenneth Frank and colleagues provide reassuring evidence that, given sufficient time and protection from further exploitation, collapsed ecosystems can and will repair themselves, but at a pace that is much slower than had been anticipated.

The ecosystem is currently dominated by smaller, plankton-eating fish but as their numbers swell and their food supply wanes, the big fish are slowly coming back. This bodes well for other perturbed, formerly cod-dominated ecosystems north of the eastern Scotian Shelf that have yet to recover.

CONTACT
Kenneth Frank (Bedford Institute of Oceanography, Dartmouth, Canada)
Tel: +1 902 426 3498; E-mail: [email protected]

ALSO IN THIS ISSUE…

[10] Second messenger role for Mg2+ revealed by human T cell immunodeficiency (pp 471-476; N&V)

[11] Two-photon laser spectroscopy of antiprotonic helium and the antiproton-to-electron mass ratio (pp 484-488; N&V)

[12] Transforming binding affinities from three dimensions to two with application to cadherin clustering (pp 510-513)

[13] Oxysterols direct B-cell migration through EBI2 (pp 519-523)

[14] Oxysterols direct immune cell migration through EBI2 (pp 524-527)

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.

AUSTRIA
Vienna: 11

BELGIUM
Gosselies: 14
Heverlee: 5

CANADA
Athabasca: 2
Burnaby: 8
Dartmouth: 9
Kingston: 9
London: 2
Vancouver: 8

CHINA
Beijing: 1
Linyi City: 1
Shanghai: 13

GERMANY
Berlin: 4
Garching: 11

HUNGARY
Budapest: 11
Debrecen: 11

ISRAEL
Jerusalem: 12
Rehovot: 4

ITALY
Brescia: 11

JAPAN
Tokyo: 11

NORWAY
Oslo: 5

SWITZERLAND
Basel: 14

UNITED STATES OF AMERICA
Alaska
Fairbanks: 6
Fort Wainwright: 6
Arizona
Tucson: 8
California
La Jolla: 14
Los Angeles: 2
Palo Alto: 5
San Diego: 13, 14
San Francisco: 4, 10, 14
Stanford: 4
Colorado
Boulder: 5
Connecticut
New Haven: 3
Florida
Gainesville: 6
Hawaii
Kamuela: 2
Massachusetts
Boston: 7
Woods Hole: 6
Maryland
Bethesda: 10
New York
New York: 12

PRESS CONTACTS…

For North America and Canada
Neda Afsarmanesh (Nature, New York)
Tel: +1 212 726 9231; E-mail: [email protected]

For Japan, Korea, China, Singapore and Taiwan
Mika Nakano (Nature, Tokyo)
Tel: +81 3 3267 8751; E-mail: [email protected]

For the UK
Rebecca Walton (Nature, London)
Tel: +44 20 7843 4502; E-mail: [email protected]

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