Ice sheet stability in West Antarctica and more of the latest research news from Nature

Pulses of warm ocean water that could reach far beneath the Filchner–Ronne Ice Shelf together with a smooth, steep bed beneath the ice sheet may affect the stability of the West Antarctic Ice Sheet, suggest two papers published this week in Nature and Nature Geoscience.

This press release contains:

---Summaries of newsworthy papers:

Geoscience: Ice sheet stability in West Antarctica
Genomics: New recurrent mutations in melanoma
Comment: A better way to dispose of plutonium
Cardiovascular disease: Double-hit for pregnancy-related heart disease
Planetary science: Measuring Martian sand dunes
Animal behaviour: Think tanks for fish
Microbiology: Knowing your gut
Cancer: A double-edged sword for tumour survival
Evolution: Species diversify with flying colours
And finally... Materials science: A cracking fabrication technique

---Geographical listing of authors

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[1] & [2] Geoscience: Ice sheet stability in West Antarctica (pp 225-228; N&V; AOP)

DOI: 10.1038/ngeo1468
DOI: 10.1038/nature11064

Pulses of warm ocean water that could reach far beneath the Filchner–Ronne Ice Shelf together with a smooth, steep bed beneath the ice sheet may affect the stability of the West Antarctic Ice Sheet, suggest two papers published this week in Nature and Nature Geoscience. Projected changes in warm ocean currents in this region by the end of the twenty-first century, presented in one of the studies, could erode the buttressing Filchner–Ronne Ice Shelf. The surface and shape of the sea bed beneath two ice streams that feed the ice shelf — detected in the other study — would be unlikely to delay retreat.

In the Nature article, Hartmut Hellmer and colleagues use models to predict future ocean warming in this region. Their projections, based on projected loss of sea ice in the Weddell Sea, suggest that winds will drive warm ocean currents far beneath the Filchner–Ronne Ice Shelf. Towards the end of the twenty-first century, water temperatures under the ice may be up to two degrees warmer than present temperatures, which the simulations indicate will enhance melting. Although the results may depend on the specific model used, preliminary results from another model — albeit from shorter simulations — are generally supportive.

In the Nature Geoscience article, Martin Siegert and colleagues surveyed the thickness of the Institute and Möller ice streams — that feed the Filchner–Ronne Ice Shelf — to determine the underlying landscape. Their measurements reveal a steep reverse slope and a large subglacial basin (around the size of Wales) upstream of where the West Antarctic Ice Sheet meets the Weddell Sea. The bed is fairly smooth, with little in the way of ‘pinning points’ that could delay retreat of the ice sheet.

Angelika Humbert considers the issues associated with both sets of findings in an accompanying News & Views article in Nature Geoscience. Taken together, she suggests that the smooth, steep surface below the ice sheet and the projected increasing melt rates raise concerns about the Weddell Sea sector of the West Antarctic Ice Sheet.

CONTACT
Hartmut Hellmer (Alfred-Wegener-Institut für Polar und Meeresforschung, Bremerhaven, Germany) Author - Nature paper [1]
Tel: +49 471 4831 1794; E-mail: [email protected]
Please note that this author will be travelling until Monday 7th May

Ralph Timmermann (Alfred-Wegener-Institut für Polar und Meeresforschung, Bremerhaven, Germany) Co-author - Nature paper [1]
Tel: +49 471 4831 1796; E-mail: [email protected]

Martin Siegert (University of Edinburgh, UK) Author - Nature Geoscience paper [2]
Tel: +44 131 650 7543; E-mail: [email protected]

Angelika Humbert (Alfred-Wegener-Institut, Bremerhaven, Germany) Author - Nature Geoscience N&V
Tel: +49 471 4831 1834; E-mail: [email protected]

**Please note a telephone press briefing will take place UNDER STRICT EMBARGO on Tuesday 08 May at 1500 London time (BST) / 1000 US Eastern Time.**

Hartmut Hellmer, Martin Siegert and Angelika Humbert will discuss their articles. This will be followed by a Q&A session.

Dial-in details are as follows:
For reporters calling from the United Kingdom: 0808 109 0700
For reporters calling from outside the United Kingdom: +44 20 3003 2666
Password: Nature press briefing

[3] Genomics: New recurrent mutations in melanoma (AOP)

DOI: 10.1038/nature11071

Melanoma — a highly lethal and aggressive form of skin cancer — has had its genome sequenced. Rates of mutations are highest in patients with chronic sun exposure, confirming the role of sun exposure in disease development. The findings, reported in Nature this week, provide insights into the genetic changes underlying human melanoma tumours and may assist the development of much needed new therapeutic strategies.

By performing whole-genome sequencing of 25 metastatic melanomas, Levi Garraway and colleagues find that the mutation rate varies widely and is associated with the level of sun exposure. A number of recurrent mutations are identified that have not previously been implicated in this tumour type; in particular, the authors discover that a gene called PREX2 — previously implicated in breast cancer — is mutated in approximately 14% of cases. Although the precise role of PREX2 in melanoma remains to be elucidated, its mutant form is associated with accelerated tumour formation. Understanding the genomic landscape that contributes to melanoma development should provide new insights into tumour biology, therapeutic resistance, and developing urgently needed treatments to control this disease, the authors conclude.

CONTACT
Levi A. Garraway (The Broad Institute of Harvard and MIT, Cambridge, MA, USA)
Tel: +1 617 632 6689; E-mail: [email protected]

Comment: A better way to dispose of plutonium (pp 167–168)

The world today has a stock of about 500 tonnes of separated plutonium ― enough to make 100,000 nuclear weapons. According to the US National Academy of Sciences, this represents a "clear and present danger", yet no country has worked out a good method to dispose of the material. The United Kingdom (which has the world's largest civilian stocks of plutonium) is considering following in the footsteps of the United States, France and Japan by converting its plutonium into mixed-oxide fuel (MOX) for use in proposed nuclear power reactors. In a Comment piece in Nature, Rodney Ewing, Allison Macfarlane, and colleagues urge Britain to reconsider.

The MOX fuel strategy is costly, the authors argue, and has been combined in France and Japan with a programme of continuing to separate out yet more plutonium, just when the world should be reducing its stockpiles of this dangerous material. Although 'recycling' plutonium from spent reactor fuel might sound like a sensible plan, it has actually added about US$750 million each year to the cost of electric power generation in France. A plant designed to recycle spent reactor fuel in Japan has twice shut down because of malfunctions. And a previous effort to build a MOX plant in Britain didn't go well. It operated at only 1% of its design capacity; in August 2011, after expenditures of £1.4 billion ($2.3 billion), it was shut down.

Instead, the authors argue, separated plutonium should simply be buried underground. This strategy has been evaluated, but never implemented. "It is time to follow a different path, in which plutonium is treated unambiguously as the dangerous weapons material that it is," they write. "Britain should seriously evaluate the less costly and less risky method of direct plutonium disposal, and take the opportunity to lead the world towards a better solution for reducing stockpiles."

CONTACT

Rodney Ewing (University of Michigan, Ann Arbor, MI, USA)
Tel: +1 734 763 9295; E-mail: [email protected]

Allison Macfarlane (George Mason University, Fairfax, VA, USA)
Tel: +1 703 993 9144; E-mail: [email protected]

For background information on the News Features, please contact the press office.

[4] Cardiovascular disease: Double-hit for pregnancy-related heart disease (AOP)

DOI: 10.1038/nature11040

The cause of a form of heart disease called peripartum cardiomyopathy, which affects women late in pregnancy and after giving birth, is uncovered in this week’s Nature. Evidence from mice and humans indicates that peripartum cardiomyopathy is a vascular disease. Understanding the underlying mechanisms offers insights into how this disease can be treated.

Zoltan Arany and colleagues suggest that peripartum cardiomyopathy is a two-hit disease caused by deregulated blood vessel formation. Signals released during the late stages of pregnancy that prevent normal blood vessel growth (angiogenesis) are considered the first hit. These signals are excessively elevated in women with peripartum cardiomyopathy, and are also high in women with pre-eclampsia (pregnancy-induced high blood pressure). Insufficient pro-angiogenic defences are implicated as the second contributing factor.

These data may explain why pregnancy triggers peripartum cardiomyopathy and why pre-eclampsia is a risk factor for this disease. The authors conclude that therapies that encourage blood vessel formation may be beneficial for peripartum cardiomyopathy.

CONTACT
Zoltan Arany (Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA)
Tel: +1 617 735 4252; E-mail: [email protected]

[5] Planetary science: Measuring Martian sand dunes (AOP; N&V)

DOI: 10.1038/nature11022

Evidence for recent modifications to the Martian surface is reported in Nature this week. Observations of dunes on Mars reveal very large movements of sands, and indicate that these dunes can be as active as those on Earth

Recent studies have suggested that there have been sand movements on Mars, but the extent of this movement and whether these processes are current has remained unclear. Nathan Bridges and colleagues use high-resolution images of the Nili Patera dune field to measure migration of sand ripples. They find that ripple migration occurs across the entire field and use their measurements to estimate sand flux. These calculations reveal that sand dunes on Mars move volumes of sand equivalent to those in Victoria Valley, Antarctica.

Contrary to a previous circulation model of the Martian atmosphere, the present findings demonstrate that the conditions on Mars are sufficient to transport large amounts of sand. The authors suggest that there may be fundamental differences in how sand is mobilized on Mars compared with Earth.

CONTACT
Nathan T. Bridges (Johns Hopkins University, Laurel, MD, USA)
Tel: +1 443 778 5753; E-mail: [email protected]
Jasper Kok (Cornell University, Ithaca, NY, USA) N&V author

Tel: +1 607 254 6396; E-mail: [email protected]

[6] Animal behaviour: Think tanks for fish (AOP)

DOI: 10.1038/nature11057

Imaging the brains of fish in virtual-reality swimming systems enables scientists to monitor brain activity associated with movement. An account of such an experiment is published in this week’s Nature. The findings allow the researchers to understand which brain circuits are involved in specific activities.

Improvements in imaging technology have assisted the study of brain activity, and zebrafish provide a useful model for studying activity associated with movements in response to different stimuli. Florian Engert and colleagues track the dynamics of this behaviour in paralysed fish (restricting their movement prevents blurring on images) navigating a virtual-reality environment. Flowing water and visual stimuli trick the fish into thinking they are swimming, and they quickly respond to changes. With this experiment the authors identify neural populations that are activated during specific phases of this activity.

The authors were able to map different types of neural dynamics to distinct regions in the brain. They conclude that these findings represent a step towards understanding the role of neural circuits in adaptive movement behaviours.

CONTACT
Florian Engert (Harvard University, Cambridge, MA, USA)
Tel: +1 617 495 4382; E-mail: [email protected]

[7] Microbiology: Knowing your gut (AOP)

DOI: 10.1038/nature11053

The impact of diet and genetics on the composition and function of human gut microbial communities is assessed in Nature this week. Samples from populations in three different countries are analysed for differences in their microbiota. The study offers an opportunity to discover how our gut microbiota evolve within a lifespan, vary between distinct cultures, and respond to changing lifestyles.

Microorganisms that live within us have a number of useful functions, such as releasing energy from undigested carbohydrates and repressing the growth of harmful microbes. To investigate the causes of diversity in gut microbiota between individuals, Jeffrey Gordon and co-workers analyse samples from over five-hundred individuals from the USA, Venezuela and Malawi. They find shared features until the age of three, including age-associated changes in production and utilization of vitamins, and similarities among family members that extend across cultures. Differences observed between the microbiota in individuals in the USA compared with those in Venezuela and Malawi are attributed to differences in their diets; typical USA diets are rich in protein, whereas Venezuelan and Malawi diets are dominated by starch.

Together, these findings suggest that the microbiota should be considered when assessing the nutritional needs of humans at various stages of development, the authors conclude.

CONTACT
Jeffrey I. Gordon (Washington University in St. Louis, MO, USA)
Tel: +1 314 362 7243; E-mail: [email protected]

[8] Cancer: A double-edged sword for tumour survival (AOP)

DOI: 10.1038/nature11066

A pathway that promotes cancer cell survival and tumour growth is described in Nature this week. The work uncovers a mechanism that may help tumour cells to survive energy stress conditions, a critical step for tumour growth. Surprisingly, components of this pathway have previously been shown to have a tumour-suppressing effect.

Nissim Hay and co-workers uncover how a pathway that stimulates metabolic adaptation, known as the LKB1–AMPK pathway, leads to prolonged tumour cell survival. A key component of this pathway has been shown to have tumour-suppressing activity, but under metabolic stress Hay and colleagues find that a certain component of the pathway is activated. This aspect of the pathway, which regulates the balance between fatty acid synthesis and oxidation, is critical for cancer cell survival during metabolic stress. The authors suggest that this mechanism operates during early stages of tumorigenesis, to help tumour cells survive energy stress conditions.

CONTACT
Nissim Hay (University of Illinois at Chicago, IL, USA)
Tel: +1 312 355 1684; E-mail: [email protected]

[9] Evolution: Species diversify with flying colours (AOP)

DOI: 10.1038/nature11050

*** This paper will be published electronically on Nature's website on 09 May 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 10 May, but at a later date. ***

The existence of several colour variants within bird populations is associated with accelerated generation of new species, according to a report in Nature this week. This relationship has been predicted and the present study confirms the theory, indicating that several ecological, geographical and genetic factors, but not sexual selection, are involved.

The study of colour polymorphic species — populations with multiple, discrete colour forms — provides insights into the processes involved in species diversity. To determine whether evolutionary processes underlying colour polymorphism can generate differences between populations, Andrew Hugall and Devi Stuart-Fox look at evolutionary relationships in several bird groups. They show that high prevalence of colour polymorphism leads to rapid generation of new species, as noted in three families of birds of prey. This association also seems to be linked to the range and diversity of the environments occupied and behavioural patterns.

The authors suggest that the coexistence of multiple colours within populations may represent incomplete speciation. Newly generated species from colour-polymorphic species tend to be uniform in their colours, which may explain why colour polymorphism is a fairly rare trait.
CONTACT
Devi Stuart-Fox (University of Melbourne, Australia)
Tel: +1 6138 344 4846; E-mail: [email protected]

[10] And finally... A cracking fabrication technique (pp 221-224); N&V)

A technique that can produce controlled cracking patterns on demand could be used to engineer materials with practical applications in fields such as in nanotechnology and micro-scale fluidic devices — often used in chemistry and biomedical applications. Although the formation of cracks is usually considered to be detrimental, a study in this week’s Nature demonstrates that cracks can be manipulated and may one day be exploited as a nanofabrication tool.

Koo Hyun Nam and co-workers describe controlled crack initiation, propagation and termination in a thin brittle film deposited on a silicon wafer. A range of pre-determined crack patterns can be initiated by etching notches on the silicon wafer, which produce stress points on the overlying brittle film. The authors produce straight, oscillating and stitch-like cracks by choosing a specific crystal orientation of the underlying silicon wafer. They can even control the direction of the cracks and bend them around corners. Finally, they design special crack stop structures in the silicon wafer to terminate the fracture process at designated points.

Nam and colleagues suggest that their method may enable the development of a cheaper and quicker way to produce nano-patterns, compared with current state-of-the-art techniques. The approach can be easily scaled-up without affecting cost and processing time, say the authors.

CONTACT
Koo Hyun Nam (Ewha Womans University, Seoul, Korea)
Tel: +82 23277 5953; E-mail: [email protected]

Antonio Pons (University of Catalonia, Barcelona, Spain) N&V author
E-mail: [email protected]

ALSO IN THIS ISSUE…

[11] Engineering the thirdwave of biocatalysis (pp 185-194)

[12] The suppression of star formation by powerful active galactic nuclei (pp 213-216)

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
Carlton: 9
Epping: 12
Melbourne : 9

AUSTRIA
Vienna: 3

CANADA
Lethbridge: 12
Vancouver: 12

FRANCE
Gif-sur-Yvette: 12
Marseille: 12
Orsay: 12
Paris: 12

GERMANY
Bremerhaven: 1
Essen: 3
Garching bei Munchen: 12
Greifswald: 11
Hamburg: 1
Hannover: 4

ISRAEL
Rehovot : 3

ITALY
Padova: 12

KOREA
Seoul: 10, 11
Yusong-Gu: 10

PORTUGAL
Lisboa: 6

PUERTO RICO
Rio Piedras: 7

SPAIN
La Laguna: 12
Madrid: 12

SWITZERLAND
Visp: 11

THE NETHERLANDS
Noordwijk: 12

UK
Aberdeen: 2
Brighton: 12
Cambridge: 2, 6
Cardiff: 12
Chilton: 12
Dorking: 12
Edinburgh: 2, 12
Exeter: 1, 2
Hatfield: 12
Leicester: 12
London: 12
Manchester: 12
Oxford: 12
York: 2

UNITED STATES OF AMERICA
Arizona
Flagstaff: 7
Tucson: 5
California
Irvine: 12
Moffett Field: 12
Pasadena: 5, 12
Redwood City: 11
South San Francisco: 8
Colorado
Boulder: 7, 12
Georgia
Atlanta: 11
Illinois
Chicago: 8
Massachusetts
Boston: 3, 4
Cambridge: 3, 6, 12
Maryland
Chevy Chase: 3
Greenbelt: 12
Laurel: 5
Minnesota
Saint Paul: 11
Missouri
St Louis: 7
New Jersey
Rahway: 11
New York
New York: 3
Pennsylvania
Philadelphia: 7
Texas
Austin: 2
Houston : 3

VENEZUELA
Caracas: 7
Puerto Ayacucho: 7

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

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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Published: 09 May 2012

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