Earth sciences: Strange brew

Cell biology: Understanding ageing, Planetary science: Asteroids show signs of ageing, Volcanology: The heat is on explosive eruptions, Cancer: Two faces of p53, Synthetic chemistry: Special protection, Fluid dynamics: Flows stay smooth, Bottom-dwellers use nitrate to survive in mud


This press release is copyright Nature. VOL.443 NO.7107 DATED 07 SEPTEMBER 2006

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- Earth sciences: Strange brew

- Cell biology: Understanding ageing

- Planetary science: Asteroids show signs of ageing

- Volcanology: The heat is on explosive eruptions

- Cancer: Two faces of p53

- Synthetic chemistry: Special protection

- Fluid dynamics: Flows stay smooth

And finally... Bottom-dwellers use nitrate to survive in mud

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· Geographical listing of authors

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[1] Earth sciences: Strange brew (pp 71-75)

A new study of Siberian lakes shows that bubbling is a larger source of methane to the atmosphere than previously believed, requiring current estimates of emissions from northern wetlands to be increased by 10 to 63%. The research, by Katey Walter and colleagues, will be published in Nature this week.

When frozen ground thaws along lake margins in North Siberia, dead plant and animal remains fall to the lake floor, where they decompose to produce methane, a potent greenhouse gas. The methane bubbles up to the lake surface and into the atmosphere, contributing to global warming. Until now, the relative importance of these bubbles has been uncertain because the patchiness of the phenomenon makes it hard to measure. Recent expansion of thaw lakes in the region may have markedly increased methane emissions, suggesting that thaw-lake methane could be a positive-feedback mechanism to climate warming.


Katey Walter (University of Alaska Fairbanks, AK, USA)
Tel: +1 907 424 5800 x222; E-mail: [email protected]

[2], [3] & [4] Cell biology: Understanding ageing (AOP; N&V)

DOI: 10.1038/nature05091
DOI: 10.1038/nature05092
DOI: 10.1038/nature05159

***These paper will be published electronically on Nature's website on 6 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 them on this release to avoid multiple mailings they will not appear in print on 7 September, but at a later date.***

Three papers to be published online in Nature this week help answer a fundamental question in mammalian ageing: why progenitor cells gradually lose their ability to divide and generate new cells as they grow old. They show that a protein called p16INK4a limits the regenerative abilities of such cells in ageing bone marrow, brain and pancreas.

p16INK4a is a protein involved in cell cycle control, and is already known to suppress cancer. The teams show that the activity of the p16INK4a gene increases as progenitor cells in the three mouse tissues lose their ability to self-renew. Sean Morrison and his colleagues studied neural progenitors in the mouse forebrain; Norman Sharpless and his team studied progenitors in the pancreatic islets that make insulin-secreting beta-cells; and David Scadden and his group examined haematopoietic bone marrow cells that make blood.

The teams genetically engineered mice that lacked p16INK4a and then examined them when they reached old age, some 18 months later. Progenitor cells in these mice cling onto their youth - they do not show the normal age-dependent decline in proliferation.

The work also suggests that type 2 diabetes might partly be explained by the failure of the pancreatic islets to renew with ageing, and perhaps that blocking this protein in certain tissues might combat certain effects of ageing.


Sean Morrison (University of Michigan, Ann Arbor, MI, USA)
Tel: +1 734 647 6261; E-mail: [email protected] Author paper [2]

Norman Sharpless (University of North Carolina School of Medicine, Chapel Hill, NC, USA)
Tel: +1 919 966 1185; E-mail: [email protected] Author paper [3]

David Scadden (Harvard Stem Cell Institute, Boston, MA, USA)
Tel: +1 617 726 5615; E-mail: [email protected] Author paper [4]

Judith Campisi (Lawrence Berkeley National Laboratory, Berkeley, CA, USA)
Tel: +1 510 486 4416; E-mail: [email protected] N&V author

[5] Planetary science: Asteroids show signs of ageing (pp 56-58)

A close encounter of a spacecraft with an asteroid has provided space scientists with a vital clue to the origin of meteorites. Takahiro Hiroi and colleagues discovered that an asteroid has patchy surfaces in different stages of ageing. Meteorites come from asteroids, so this suggests that the ageing process may be the reason why most meteorites look different from most asteroids.

This discrepancy between meteorites found on Earth and the composition of asteroids as judged from their surface appearance has been interpreted as a possible indication that the asteroid surfaces become altered over time, a process called space weathering. It is thought that this process makes asteroids gradually darker and more 'red'. The team were able to test this idea thanks to the close observation of the 550-metre-wide asteroid 25143 Itokawa by the Japanese Hayabusa spacecraft, launched in May 2003, which had a rendezvous with Itokawa at the end of 2005. The spacecraft saw variations in brightness and 'redness' on the asteroid's surface, indicating differing degrees of space weathering.

In this week's Nature, the researchers attribute the differences in appearance to varying amounts of very small particles of iron. They think that the most abundant types of meteorites probably come from so-called S-type asteroids, which are the most common in the asteroid belt: the two kinds of objects now look different because the asteroid surfaces have been changed by space weathering since the meteorites were chipped off them long ago.


Takahiro Hiroi (Brown University, Providence, RI, USA)
Tel: +1 401 863 3776; E-mail: [email protected]

[6] Volcanology: The heat is on explosive eruptions (pp 76-80)

As water-saturated magma decompresses and crystallizes it heats up, according to research published in Nature this week. The finding is surprising as crystallization usually occurs as a liquid cools, and the reported heating effect is greatest at low pressure, when crystal growth is at its maximum.

Explosive volcanic eruptions are difficult to model, as the processes involved occur deep below the Earth's surface and depend on a complex interplay of different factors related to the physical properties of the magma, such as temperature, viscosity, water and gas content. A key unknown is the temperature variation in magma rising through the volcano as it loses gas and crystallizes on the way; but tracking temperature changes at a depth of several kilometres has proved difficult.

An alternative method is to analyse the contents of fluid inclusions in solidified lava - pockets of melt contained within crystals from previous eruptions can provide a snapshot of magma reservoir conditions just before an eruption occurs. Jon Blundy and colleagues studied the chemical and textural compositions of products from two active volcanoes - Mount St Helens (Washington State, USA) and Shiveluch (Kamchatka, Russia). They found that the temperature of ascending magma increases by up to 100 degrees Celsius owing to the release of latent heat of crystallization.

The work builds on previous studies by the same team that show a consistent relationship between the compositions of the melt inclusions and the type of eruption that brought the material to the surface. The analysis of melts from Mount St Helens and Shiveluch reinforces this theory, and suggests that crystallization is particularly important during an eruption as it affects the style and intensity of the event.


Jon Blundy (University of Bristol, UK)
Tel: +44 117 954 5447; E-mail: [email protected]

Please note the author is travelling so it may be easier to contact:

Madeleine Humphreys (University of Cambridge, UK)
Tel: +44 1223 765 260; E-mail: [email protected]

Cathy Cashman (University of Oregon, Eugene, OR, USA)
Tel: +1 541 346 4323; E-mail: [email protected]

[7] Cancer: Two faces of p53 (AOP)
DOI: 10.1038/nature05077

***This paper will be published electronically on Nature's website on 6 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 7 September, but at a later date.***

A paper to be published online this week by Nature challenges the conventional view of p53, a central protein in protecting against cancer. By switching the function of this protein on and off in mice, researchers have shown that its role in responding to DNA damage is irrelevant to protecting against a certain type of cancer induced by irradiation.

It was thought that one of the mechanisms by which p53 suppresses tumours was to respond to DNA damage and halt cell division or trigger cell death. Gerard Evan and his colleagues irradiated mice that had been genetically engineered to carry a p53 gene encoding a protein whose function can be switched on and off with a simple chemical treatment.

When p53 was switched on during irradiation it triggered the induction of cell death in DNA-damaged tissues, but did not protect the mice from developing lymphomas at a later time when compared to mice in which p53 remained switched off. Switching p53 on eight days after irradiation, however, protected the mice from cancer. This protection required a second tumour suppressor protein called p19ARF. The results suggest that DNA-damage response and tumour suppression are unlinked functions of p53, each induced by different signals.

The results also suggest that the p53-dependent DNA-damage response causes much of the life-threatening tissue damage and side effects caused by radiation and chemotherapy - and that a brief dose of a drug that blocks p53 function during these treatments might prevent the unwanted effects while still maintaining tumour protection.


Gerard Evan (University of California, San Francisco, CA, USA)
Tel: +1 415 514 0438; E-mail: [email protected]

[8] Synthetic chemistry: Special protection (pp 67-70; N&V)

In Nature this week, Amir Hoveyda and colleagues present a simple metal-free catalyst that can be used to shield a specific alcohol with a 'protecting group' without modifying another alcohol that is nearby. Protecting groups are often needed in organic synthesis to shield one part of a molecule from chemical change while another part of that same molecule is altered. This catalyst puts a protecting group called a silyl ether onto a class of compounds called secondary alcohols, and by protecting that specific alcohol, a chemist can now selectively modify the remaining 'unprotected' alcohol.

Reliable, selective and environmentally friendly chemical reactions are often needed to synthesize natural products and new drugs efficiently. Organic chemists often use a catalyst - a chemical substance that facilitates the transformation of a reagent to a product without itself being transformed - in such syntheses; though many catalysts have been discovered in the past fifty years, the search continues for catalysts that can rapidly produce important molecules in high purity and high yields.

Because this catalyst does not contain any metals it is more environmentally friendly - or 'greener' - than many other catalysts. In addition, the catalyst can easily be prepared from commercially available materials and cuts down on the number of reaction steps, the time, and the chemical waste needed to make certain molecular 'building blocks' that have been used by other chemists to make nucleosides, like the antiretroviral drug AZT, and prostaglandin analogues, which are used to treat glaucoma.


Amir Hoveyda (Boston College, Chestnut Hill, MA, USA)
Tel: +1 617 552 3618; E-mail: [email protected]

Scott Denmark (University of Illinois, Urbana, IL, USA)
Tel: +1 217 333 0066; E-mail: [email protected]

[9] Fluid dynamics: Flows stay smooth (pp 59-62; N&V)

Turbulence in fluid flow can be a nuisance: it makes the flow unpredictable and harder to control, and can increase drag when it happens at the surface of bodies moving through liquids. So the findings of Björn Hof and colleagues reported in Nature this week might bring welcome news to fluid engineers. They show that, once turbulence appears in the flow of water down a pipe, it is not necessarily there to stay, but can give way again to smooth flow.

Turbulence can come and go in pipe flow - but this was thought to happen only for flow rates that are close to the threshold at which turbulence first appears. Below this threshold, the flow is said to be laminar: the speed of fluid flow simply increases steadily with increasing distance from the pipe wall, free from any eddies. This smooth laminar flow is often a desirable state in industrial processes that involve flow of liquids and gases.

Transient turbulence was thought to give way to permanent turbulence above a critical flow rate - which depends, among other things, on the pipe's width. The team carried out detailed measurements of water flow along a 30-metre copper pipe 4 millimetres wide. By monitoring the flow all along this long pipe, they have been able to check just how persistent a region of turbulence is as it travels. They find that even above the critical flow rate, turbulence can still revert to laminar flow eventually. The length of time the turbulence persists increases rapidly with increasing flow rate, but does not become infinite as soon as the threshold is exceeded: if given long enough, the flow will always return to laminar. This means that the laminar state is never truly 'lost', and might be recovered earlier with suitable fine-tuning of the flow.


Björn Hof (University of Manchester, UK)
Tel: +44 7875 949 730; E-mail: [email protected]

Temporary E-mail: [email protected]

Daniel Perry Lathrop (University of Maryland, College Park, MA, USA)
Tel: +1 301 405 1594; E-mail: [email protected]

[10] And finally... Bottom-dwellers use nitrate to survive in mud (pp 93-96)

Living under suffocating layers of ocean mud sounds like a tough way to survive. But biologists have discovered that a common, marine, single-celled organism does just that, surviving by converting nitrate to dinitrogen gas. It's the first example of this process, called denitrification, occurring in an eukaryote - it was previously thought to be confined to bacteria and archaea.

The benthic foraminifera Globobulimina pseudospinescens can accumulate nitrate at concentrations much higher than that in the surrounding seawater and use it to respire in the otherwise uninhabitable seafloor sludge, report Nils Risgaard-Petersen and colleagues in this week's Nature. This energetically expensive undertaking allows them to migrate deep into the sea sediment, using the nitrate for respiration much as our cells use oxygen. This surprising discovery that this abundant organism uses denitrification suggests that much remains to be learned about the global nitrogen cycle.


Nils Risgaard-Petersen (National Environmental Research Institute, Silkeborg, Denmark)
Tel: +45 892 01478; E-mail: [email protected]

Please note the author is away at the moment so it may be easier to contact:

Lars Peter Nielsen (University of Aarhus, Denmark)
Tel: +45 8942 3250; E-mail: [email protected]

Niels Peter Revsbech (University of Aarhus, Denmark)
Tel: +45 8942 3244; E-mail: [email protected]


[11] A class of non-precious metal composite catalysts for fuel cells (pp 63-66)

[12] Interference among deleterious mutations favours sex and recombination in finite populations (pp 89-92)

[13] Unravelling the dynamics of RNA degradation by ribonuclease II and its RNA-bound complex (pp 110-114)

[14] Nitrogen balance and Arctic throughflow (p 43)


***This paper will be published electronically on Nature's website on 6 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 7 September, but at a later date.***

[15] Structure of the insulin receptor ectodomain reveals a folded-over conformation
DOI: 10.1038/nature05016


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.


Parkville: 15


Sidney: 14

Vancouver: 12

Arhus: 10

Silkeborg: 10


Marburg: 9


Kanagawa: 5

Kobe: 5

Mizusawa: 5

Tokyo: 5


Seoul: 5

Lisbon: 13


Cherskii: 1


Madrid: 10

Seville: 2


Gothenburg: 10


Delft: 9

Nijmegen: 10

Utrecht: 10


Bristol: 6

Cambridge: 6, 13

Edinburgh: 12

Manchester: 9



Fairbanks: 1

San Francisco: 7


Tallahassee: 1

Laurel: 5

Boston: 3, 4

Cambridge: 4

Chestnut Hill: 8

Ann Arbor: 2

New Mexico

Los Alamos: 11
New York

Ithaca: 5
North Carolina

Chapel Hill: 2, 3, 4


Eugene: 6

Pittsburgh: 4
Rhode Island

Providence: 5


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
Rinoko Asami, Nature Tokyo
Tel: +81 3 3267 8751; E-mail: [email protected]

For the UK/Europe/other countries not listed above
Katherine Anderson, Nature London
Tel: +44 20 7843 4502; E-mail [email protected]

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Published: 06 Sep 2006

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