The future of clean water

Summaries of newsworthy research include: More than just a drinking problem, Methane found on an extrasolar planet, Dwindling populations become even more volatile, Spring genes, Eliminating antimatter, A fresh look at the mantle, Unusual reproduction, Analysing martian meteorites and Life’s winners don’t punish others

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This press release is copyright Nature.

VOL.452 NO.7185 DATED 20 MARCH 2008

This press release contains:

· Summaries of newsworthy papers:

Technology: The future of clean water

Water shortages: More than just a drinking problem

Space science: Methane found on an extrasolar planet

Endangered species: Dwindling populations become even more volatile

Breeding: Spring genes

Cosmology: Eliminating antimatter

Geochemistry: A fresh look at the mantle

Plant biology: Unusual reproduction

Cosmochemistry: Analysing martian meteorites

And finally… Life’s winners don’t punish others

· Mention of papers to be published at the same time with the same embargo

· Geographical listing of authors

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[1] Technology: The future of clean water (pp 301-310)

A revolution in water purification and treatment is underway. More and more scientists and technologists from around the world are working to identify cheap, robust methods to purify water, while at the same time minimizing the use of chemicals and environmental impact. A review article in Nature this week highlights some of the technologies being developed to improve the disinfection and decontamination of water, and the safe re-use of wastewater and efficient desalination of sea and brackish water.

A growing number of contaminants are entering the water supplies of both developing and developed nations. The detection and accurate measurement of these contaminants in water supplies are technically challenging and expensive. Furthermore, conventional methods of purification are often chemically and energetically intensive, requiring considerable engineering expertise, infrastructure and capital, which limit their use in many countries. The treatments themselves often add to the problem of contamination and salting of freshwater sources.

Mark Shannon and colleagues look at the problems of current water purification techniques and explore some of the next-generation systems applying the latest science to address these problems. Among other approaches, they consider the use of new photocatalyst materials to deactivate waterborne viruses, the application of nanostructured membranes for contaminant capture, and inspiration from ion channels for improved desalination devices.

The authors believe that through scientific investigation of the aqueous interface between the chemicals in water and the materials used for treatment, new, sustainable, affordable and safe methods to increase clean water supplies for the whole world can be developed.

CONTACT

Mark Shannon (University of Illinois at Urbana-Champaign, Urbana, IL, USA)
Tel: +1 217 244 1545; E-mail: [email protected]

Water shortages: More than just a drinking problem

In this issue of Nature, a collection of News features and Commentary articles tackles the science, economics and politics of the global water crisis.

In some parts of the world, people use as much water running electric appliances and turning on lights as they do taking showers and watering lawns. And every time people discard food, they throw away precious water resources – it takes a staggering 15,500 litres of water to produce a kilogram of industrial beef.

Taking water for granted is not an option for the two billion or so people around the world who lack access to safe drinking water or have little or no sanitation. Do we have the resources — and the will — to provide enough water to support a booming population? The effects of water shortages are already spilling over from health and sanitation into other key economic activities — not least agriculture and energy production.

Some of this looming crisis will be driven by climate pressures, as soils get drier and rainfalls more unpredictable in a warming world. But much of it will be driven by population growth and rapid economic development, especially in regions such as southeast Asia.

The Commentary and feature writers ask how prepared we are for this crisis. Are we ready for the populations of India and China to switch to more protein-rich western diets? Or for when these nations start consuming energy at the same intensity as the developed world? These trends will add pressure to already stretched water resources in these parts of the world.

Elsewhere in the issue, an Essay explains how physicists still argue over theories describing the structure of water. And Books & Arts review a documentary on the privatization of water supplies, as well as art inspired by water’s surprising patterns.

CONTACT

Commentary: Improving on haves and have-nots (pp 283-284)

Jamie Bartram (World Health Organisation, Geneva, Switzerland)

Tel: +41 22 791 3537; E-mail: [email protected]

Commentary: The energy challenge (pp 285-286)

Mike Hightower (Sandia National Laboratories, Albuquerque, NM, USA)

E-mail: [email protected]

Essay: Water – an enduring mystery (pp291-292)

News Feature: More crop per drop (pp 273-277)

News Feature: A long dry summer (pp270-273)

To follow up on this content, please contact the press office.

[2] Space science: Methane found on an extrasolar planet (pp 329–331)

Scientists have detected the presence of methane and confirmed the presence of water in the atmosphere of an extrasolar planet. The results, reported in this week’s Nature, help to build a better picture of the atmospheric and chemical processes occurring on the planet.

Searching for water, carbon monoxide and methane on extrasolar planets is a high priority. Chemical signatures picked up by telescopes can reveal key information about atmospheric conditions on the planet but emission spectra can be difficult to obtain.

Mark Swain and colleagues observed the transiting planet HD 189733b in the constellation Vulpecula. The planet — of a type often referred to as a ‘hot Jupiter’ — is like Jupiter, made of gas but orbits much closer to its sun. Previous studies have predicted that methane and water would be present in the atmosphere, just like on Jupiter, but until now no definitive evidence has been found.

Using a near-infrared transmission spectrum obtained by the Hubble Space Telescope, the team confirm the presence of methane in the atmosphere. They also find a resolved water-vapour band, but carbon monoxide, originally expected to be abundant in the upper atmosphere, was not identifiable.

CONTACT

Mark Swain (California Institute of Technology, Pasadena, CA, USA)
Tel:+1 818 455 2396; E-mail: [email protected]

Adam Showman (University of Arizona, Tucson, AZ, USA) N&V author
Tel: +1 520 621 4021; E-mail: [email protected]

[3] Endangered species: Dwindling populations become even more volatile (pp 344-347)

A new worldwide study of data from fisheries shows that as populations decline, the size of the yearly fluctuations in population number increases markedly. The research should help to guide efforts to protect fast-dwindling fish stocks and other endangered species.

Researchers led by Coilín Minto analysed data from almost 150 marine and freshwater fisheries around the world, and found that the variation in population survival from one year to the next increases as the species become less abundant overall. The greatest variability is seen in historically overexploited fish such as North Sea herring, they report in this week’s Nature.

Changes to population structure in severely exploited species such as cod, which have begun spawning at a younger average age in response to fishing pressure, can also have the effect of increasing annual fluctuations in total population. Understanding how such fluctuations occur could help conservationists to make more accurate predictions of how quickly such species might recover, the researchers add.

CONTACT

Colín Minto (Dalhousie University, Halifax, Nova Scotia, Canada)
Tel: +1 902 494 2146; E-mail: [email protected]

[4] Breeding: Spring genes (pp 317-322; N&V)

Researchers in Japan have discovered how the quail’s brain tells its body when spring has arrived and that it is time to breed. Their study shows how genes in the brain, triggered by lengthening spring days, have a cascade of effects that primes the quail’s body to get into reproductive condition.

These genes are activated in two waves, which have a range of effects including enlargement of the gonads, report the researchers, led by Takashi Yoshimura of Nagoya University, in this week’s Nature. The first wave of gene activation occurs roughly 14 hours after dawn on the first day of sufficient length; the second occurs roughly four hours later.

The researchers made their discovery by subjecting quails to a sudden shift in day length, from short to long, and then studying gene activation in their brains. Their analysis shows that the crucial event that triggers the cascade is the activation of a gene for a thyroid-stimulating hormone called thyrotrophin. This occurs in a brain region called the pars tuberalis, highlighting the significance of this region for the activation of springtime breeding.

CONTACT

Takashi Yoshimura (Nagoya University, Japan)
Tel: +52 789 4056; E-mail: [email protected]

Hitoshi Okamura (Kyoto University, Japan) N&V author
Tel: +81 75 753 9552; E-mail: [email protected]

[5] Cosmology: Eliminating antimatter (pp 332-335)

Evidence for a rare process that may explain why our observable Universe is dominated by matter is published in Nature this week.

The dominance of matter over antimatter in our Universe raises questions about the initial conditions of the Big Bang, and has troubled cosmologists for over 30 years. The theory goes that the current asymmetry has evolved since the Big Bang as matter and antimatter are treated differently in nature — with antimatter decaying more rapidly.

The Belle Collaboration, a large scale experiment running at the KEK high-energy physics laboratory, tackles this by using 535 million B-meson/anti-B-meson pairs to measure asymmetries. Previous work suggested a difference in the decay of charged and neutral particles — an asymmetry in the decay rate of about +7% for charged B mesons and −10% for neutral B mesons. The new study reduces uncertainty on the charged particle decay rate by a factor of 1.7, providing stronger evidence for a large deviation in direct violation between charged and neutral B meson decays.

CONTACT

Paoti Chang (National Taiwan University, Taipei, Taiwan)

Tel: +886 2 3366 5151; E-mail: [email protected]

Please note the author may be travelling during the next week. It may be easier to contact:

Wei-shu Hou (National Taiwan University, Taipei, Taiwan)

Tel: +886 2 3366 5096; Mobile: +886 0919 306146; E-mail: [email protected]

Michael Peskin (Stanford University, Menlo Park, CA, USA) N&V author
Tel: +1 650 926 3250; E-mail: [email protected]

[6] Geochemistry: A fresh look at the mantle (pp 311-316)

Upwelling mantle beneath mid-ocean ridges has a more varied composition than previously thought, according to research published in Nature this week. Fresh mantle samples from the Gakkel ridge below the Arctic Ocean reveal that the mantle is more chemically heterogeneous than indicated from mid-ocean ridge basalts — the products of mantle melting.

Recycling processes through the Earth’s mantle have been studied extensively, but indirectly, through dredging of basalt samples, but generally not by analysing the mantle rocks themselves. The Gakkel ridge — stretching for 1,800 kilometres on the Arctic seafloor — is the slowest spreading ridge on the Earth with relatively weak magmatic activity, making it an ideal location to study the chemical signature of the underlying mantle.

Chuan-Zhou Liu and colleagues studied the osmium isotope composition of mantle peridotites that were found to be up to two billion years old — some of the least-altered mantle rocks ever recovered from an ocean ridge. They discovered that some of these rocks have much more depleted osmium isotope signatures than expected, and show a greater range of ages, indicating that such heterogeneity is preserved over long time intervals, rather than being homogenized by mantle convection.

CONTACT

Chuan-Zhou Liu (Chinese Academy of Sciences, Beijing, China)
Tel: +86 10 8299 8547; E-mail: [email protected]

[7] Plant biology: Unusual reproduction (AOP)

DOI: 10.1038/nature06733

***This paper will be published electronically on Nature's website on 19 March at 1800 London time / 1400 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 20 March, but at a later date. ***

The Australasian water plant Hydatella has an unusual reproductive structure according to research published in Nature this week. The study details a number of rare embryological features, including one that is unique among flowering plants and will come as a surprise to plant biologists.

Hydatellaceae is a group of inconspicuous water plants, until recently thought to be allied to grasses. Last year, a team discovered that they are in fact primitive and part of the initial emergence of flowering plants back in the Mesozoic era, causing scientific sensation.

William Friedman follows this up with an examination of the reproductive structures of Hydatella, describing a number of rare embryological features which, in combination, are found only in members of the equally primitive Nymphaeales — water lilies. But Hydatella has one additional feature — the provisioning of the seed from maternal rather than embryonic tissue — that is unique among flowering plants but relatively common among ‘naked seed’ plants such as conifers, and could be a relic of the earliest evolutionary history of flowering plants.

CONTACT

William Friedman (University of Colorado, Boulder, CO, USA)
Tel: + 1 303 492 3082; E-mail: [email protected]

[8] Cosmochemistry: Analysing martian meteorites (pp 336-339)

In silicate rocks, the isotopic abundance of certain radiogenic elements and their decay products, such as the samarium–neodymium (Sm–Nd) system, can tell us when planetary mantles differentiated from their iron-rich cores. But this assumes that we know the initial abundance of these elements in the primordial planet, which is usually assumed to be the same as the composition of a class of primitive meteorites known as ‘chondrites’. A paper in this week’s Nature shows that the mantles of the Moon and Mars share a similar ‘non-chondritic’ isotope signature with the Earth, indicating that all three may have accreted from material in the inner Solar System, which was different from that of chondrites.

Guillaume Caro and colleagues analysed with high precision the neodymium isotope ratios in 16 martian meteorites. They found that these gave a precise indication of the age of differentiation of the martian mantle. What’s more, like the Earth and Moon, the Sm/Nd ratio of Mars was significantly higher than that of chondrites, suggesting that the martian mantle shares similarities with those of the Earth and Moon.

The authors conclude that because these isotopic ratios exceed those in chondritic material accreted in the asteroid belt that separates Mars from the outer planets, it is likely that Mars, the Earth and Moon accreted from ‘non-chondritic’ material.

CONTACT

Guillaume Caro (Centre de Recherches Petrographiques et Geochimiques, CNRS, Vandoevre les Nancy, France)
Tel: +33 3 83 59 42 23; E-mail: [email protected]

[9] And finally… Life’s winners don’t punish others (pp 348-351)

Winners in the game of life are much less likely to inflict punishments on others, according to a new study of social interactions. The discovery casts doubt on the commonly held theory that costly social punishments such as prisons evolved because everyone tends to benefit on average, despite conferring a cost to those doing the punishing.

Instead, suggest researchers led by Martin Nowak of Harvard University, costly punishments may have evolved not for the greater good, but for some other reason, such as to exert power over others and to establish dominance hierarchies.

Nowak and his team asked volunteers to play an adapted version of the classic ‘prisoner’s dilemma’ economic choice game, in which participants could vote to cooperate with a partner, resulting in a payoff for them both, or to ‘defect’, guaranteeing themselves a smaller payoff. In this version, players were also able to see the actions of others, and could subsequently vote to pay a small fee to secure a large deduction from the other player’s total.

The most successful players, who finished with the highest overall totals, tended not to punish others, whereas those with lower final totals had tended to get drawn into spiteful punishments of others, the researchers in this week’s Nature report. This suggests that punishment may not be as advantageous as previous theorists have supposed. “Winners don't punish”, the researchers say, “whereas losers punish and perish”.

CONTACT

Martin Nowak (Harvard University, Cambridge, MA, USA)
Tel: +1 617 496 4737; E-mail: [email protected]

Manfred Milinski (MPI Evolutionary Biology, Ploen, Germany) N&V author
Tel: + 49 4522 763 254; E-mail: [email protected]

ALSO IN THIS ISSUE…

[10] Translational control of the innate immune response through IRF-7 (pp 323-328)

[11] Control of chromosome stability by the b-TrCP–REST–Mad2 axis (pp 365-369)

[12] SCFb-TRCP controls oncogenic transformation and neural differentiation through REST degradation (pp 370-374)

ADVANCE ONLINE PUBLICATION

***These papers will be published electronically on Nature's website on 19 March at 1800 London time / 1400 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 20 March, but at a later date. ***

[13] Chromatin dynamics during epigenetic reprogramming in the mouse germ line

DOI: 10.1038/nature06714

[14] Integration of growth and specification in chick wing digit-patterning

DOI: 10.1038/nature06718

[15] Kemp elimination catalysts by computational enzyme design

DOI: 10.1038/nature06879

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 : 5
Sydney: 5

AUSTRIA
Vienna: 5

CANADA:

Halifax: 3

Montreal: 10

Ottawa: 10

CHINA
Beijing: 6
Hefei: 5

FRANCE

Lyon: 8, 13

Paris: 8, 13

GERMANY

Freiburg: 13

Mainz: 6

INDIA
Chandigarh: 5
Mumbai: 5

ISRAEL

Rehovot: 15

JAPAN

Chiba: 5

Funabashi: 5

Gifu: 4

Hayama: 5

Kobe: 4

Nagoya: 4, 5

Nara: 5

Niigata: 5

Osaka: 5

Saga: 5

Sendai: 5

Tagajo: 5

Tokyo: 4, 5

Tsukuba: 5

Utsunomiya: 4

Yokohama: 5

POLAND

Krakow : 5

RUSSIA

Moscow: 5

Novosibirsk: 5

Protvino: 5

SLOVENIA

Ljubljana: 5

Maribor: 5

Nova Gorica: 5

SOUTH KOREA

Daegu: 5

Jinju: 5

Seoul: 5

Suwon: 5

SWEDEN

Stockholm: 9

SWITZERLAND

Lausanne: 5

Zurich: 8

TAIWAN

Chung-li: 5

Miao Li: 5

Taipei: 5

UNITED KINGDOM

Bath: 14

Cambridge: 13

Dundee: 14

London: 2

Oxford: 8

Roslin: 4

UNITED STATES OF AMERICA

California

Los Angeles: 15

Pasadena: 2

Colorado

Boulder: 7

Connecticut

New Haven: 1

Hawaii

Honolulu: 5, 6

Indiana

Notre Dame: 1

Illinois

Urbana: 1, 5

Massachusetts

Boston: 12

Cambridge: 1, 9, 12

New Jersey

Princeton: 5

New York

New York: 5, 11

Ohio

Cincinnati: 5

Texas

Houston: 6, 11, 12

Virginia

Blacksburg: 5

Washington

Seattle: 15

PRESS CONTACTS…

For North America and Canada

Katie McGoldrick, Nature Washington

Tel: +1 202 737 2355; 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/Europe/other countries not listed above

Jen Middleton, Nature London

Tel: +44 20 7843 4791; E-mail [email protected]

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Published: 19 Mar 2008

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