Surviving in a giant's furnace

Press release from Nature. Vol.442 No.7102. Summaries of newsworthy papers include Look smart!, Genetic key to finch beak length, Evidence for plate tectonics in the early Earth, Why galaxies don't get to the point, Peering at the pairs, A rose by any other temperature


This press release is copyright Nature. VOL.442 NO.7102 DATED 03 AUGUST 2006

This press release contains:

· Summaries of newsworthy papers:

Astronomy: Surviving in a giant's furnace

Optics: Look smart!

Evolution: Genetic key to finch beak length

Tectonics: Evidence for plate tectonics in the early Earth

Astrophysics: Why galaxies don't get to the point

Superconductivity: Peering at the pairs

And finally... A rose by any other temperature

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

· Geographical listing of authors

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[1] Astronomy: Surviving in a giant's furnace (pp 543-545; N&V)

When stars grow old and expand into immense, dim objects known as red giants, it can spell doom for any inner planets they might have — the Earth is expected one far-off day to be fried by such an event. But some planet-like objects orbiting Sun-like stars might survive this phase of fiery engulfment. Pierre Maxted and colleagues think they have found such a hardy survivor.

This object is not exactly a planet, but a so-called brown dwarf: a body somewhere between the size of a very large planet and a Sun-like star. Brown dwarfs have gaseous compositions similar to stars, but aren't massive enough to ignite the nuclear fusion reactions that cause stars to shine. They do, however, undergo a brief phase of less energetic fusion processes, leaving them glowing dimly — hence the designation 'brown'.

In Nature this week the team describe how they found a brown dwarf associated with the white dwarf star WD 0137-349. White dwarfs are compact stars formed after the red giant phase, when the star shrinks and heats up again. This companion to WD 0137-349 has a mass about one-twentieth that of our Sun, and is very close to the white dwarf, at a distance of about two-thirds the Sun's radius. This means that it would certainly have been engulfed during WD 0137-349's red-giant phase.

The researchers think, however, that the brown dwarf was already formed before this phase, rather than being the result of a transfer of mass from the star onto a planet when the two bodies were enclosed by the swollen atmosphere of the red giant. In other words, brown dwarfs can withstand this immersion in the stellar furnace.


Pierre Maxted (Keele University, Staffordshire, UK)
Tel: +44 1782 583 457; E-mail: [email protected]

James Liebert (University of Arizona, Tuscon, AZ, USA)
Tel: +1 520 621 4513; E-mail: [email protected]

[2] Optics: Look smart! (pp 551-554)

Man-made miniature lenses that alter their shape and light-focusing properties, like the lens of the human eye, are described by Hongrui Jiang and colleagues in this week’s Nature. The devices, in which the lens is squeezed or flattened by a surrounding hydrogel ring that acts as an artificial muscle, could be incorporated into miniaturized systems for imaging, medical diagnostics, displays and light-based information processing.

The researchers construct their lenses from droplets of water, which bulge out through a circular aperture into a film of oil. The curvature of the bulge can be controlled by using a hydrogel ring whose walls can expand or contract, altering the volume of the reservoir of water below the aperture. The hydrogel ring comprises a soft polymer gel that changes in volume in response to various environmental stimuli, such as changes in temperature or acidity of the fluid that surrounds it.

Jiang and colleagues show that their ‘adaptive’ lenses, just one-half to a few millimetres across, can be induced to change from convex to concave, and thus alter in focal length, by a rise in temperature of around 20 degrees Celsius, or by an alteration in pH from weakly acid to alkaline. They have also made pairs of lenses that show opposite shape changes in response to pH changes, by using gel rings made from different smart polymers. This represents a first step towards whole arrays of lenses, like an insect's compound eye, each of which could have 'addressable' behaviour. The researchers admit that the shape changes are currently rather too slow for some applications, taking several tens of seconds, but this should get faster if the devices are made smaller.


Hongrui Jiang (University of Wisconsin-Madison, WI, USA)
Tel: +1 608 265 9418; E-mail: [email protected]

[3] Evolution: Genetic key to finch beak length (pp 563-567; N&V)

Researchers have pinpointed a key gene involved in the regulation of beak morphogenesis. The discovery, to be published in this week’s Nature, provides a mechanism for the diversity of beak shapes seen in Darwin’s finches.

There are 14 closely related species of Darwin’s finches (Fringillidae, Passeriformes). Each has its own characteristic beak morphology reflecting differences in diet. Cactus finches, for example, have long, pointed beaks, whereas ground finches have deep, wide beaks.

Clifford Tabin and colleagues used DNA microarray analysis to study gene expression in the developing beaks of 5 different species of finch. They found that calmodulin, a molecule involved in calcium signalling, is expressed at higher levels in the long, pointed beaks of cactus finches than in the more robust beaks of other species.

To confirm their finding, the team used genetic manipulation to artificially upregulate calmodulin activity in the developing beaks of chicken embryos. The resulting birds had cactus-finch-like beaks that were around 10% longer than normal.


Clifford Tabin (Harvard Medical School, Boston, MA, USA)
Tel: +1 617 432 7618; E-mail: [email protected]

Nipam Patel (Howard Hughes Medical Institute, Berkeley, CA, USA)
Tel: +1 510 643 4605; E-mail: [email protected]

[4] Tectonics: Evidence for plate tectonics in the early Earth (pp 559-562)

Scientists have discovered strong evidence for the existence of active plate tectonics in the Archaean era — the time when life on Earth originated. The research, reported in this week's Nature, supports the idea that tectonic processes were occurring over 2,500 million years ago, much earlier than usually thought.

Jean-Francois Moyen and colleagues studied a suite of metamorphic rocks in the Barberton region of South Africa. They found that the mineral assemblages present in these rocks point to the existence of high-pressure, low-temperature metamorphism, which in younger rocks is characteristic of subduction zones. Subduction is a central part of plate tectonics — where cold, dense, oceanic crust sinks into the Earth. Until now, the presence of tectonic processes in the Archaean era has been disputed due to the lack of such evidence for subduction in the rock record.

Jean Francois Moyen (University of Stellenbosch, South Africa)
Tel: +27 21 808 3126; E-mail: [email protected]

[5] Astrophysics: Why galaxies don't get to the point (pp 539-542)

Why don't galaxies don't look the way computer simulations of their formation predict they should? Such simulations suggest that the density of invisible 'dark matter' that constitutes most of a galaxy's mass should increase to a sharp maximum (a cusp) in the galactic centre. But observations (which can reveal the distribution of dark matter even though it can't be seen directly) show that dark matter is much more smoothly distributed, without a central cusp.

Sergey Mashchenko and colleagues try to explain this discrepancy in Nature this week. Some previous explanations have invoked new kinds of physics, but the computer simulations of galaxy formation by the team show that there's no need for such exotic proposals.

They say that the cusps, which are produced as dark matter and visible matter in the early Universe clumps together to form galaxies filled with stars, get smoothed out over a period of around a hundred million years — a short time in cosmic terms — by the effect that supernovae have on the gas that pervades the galaxies. Supernovae are stars that explode after burning up all their fuel, and these explosions stir up the interstellar gas. These random gas motions in turn agitate the dark matter, which interacts with normal matter through gravity — and this stirring washes away the dark-matter cusps, leaving the dark matter distributed as seen in galaxies today.


Sergey Mashchenko (McMaster University, Hamilton, Canada)
Tel: +1 905 525 9140; E-mail: [email protected]

[6] Superconductivity: Peering at the pairs (pp 546-550; N&V)

High-temperature superconductors, which conduct electricity without electrical resistance at relatively high temperatures, have been known for 20 years, but it is still a mystery how they work. In Nature this week, J. C. Séamus Davis and colleagues use a new technique to investigate this phenomenon at the atomic scale.

High-temperature superconductors don't work in the same way as ordinary metals — where superconductivity kicks in just a few degrees above absolute zero and electrons become bound together in pairs despite their negative charge. A lack of understanding of this electron-pairing mechanism in high-temperature superconductors is a huge obstacle to exploiting their practical potential.

The team measure energy states at very small scales; placing a fine metal tip above the surface of the superconductor bismuth strontium calcium copper oxide, they look at changes in the electrical current passing between the tip and sample as they change the tip's voltage. They find differences in the measurements as the tip is moved by a few nanometres, indicating that whatever the electron-pairing mechanism is, it varies from place to place on these scales.

The new results also shed light on one of the big questions in high-temperature superconductivity; whether phonons – lattice vibrations – play a role in mediating electron pairing, as they do for ordinary low-temperature superconductors, rather than electron–electron interactions or effects connected with magnetic atoms in the material, as has been suggested previously. Davis' work presents evidence that phonons do play such a crucial role.


Seamus Davis (Cornell University, Ithaca, NY, USA)
Tel: +1 607 254 8965; E-mail: [email protected]

Alex de Lozanne (University of Texas, Austin, TX, USA)
Tel: +1 512 471 6108; E-mail: [email protected]

[7] And finally... A rose by any other temperature (p525)

Bumblebees prefer to visit warm flowers and use the colour of the flower to predict the temperature before landing, according to a Brief Communication to be published in Nature this week. Pollinators, including bumblebees (Bombus terrestris), are known to use colour signals as indicators of nutritional rewards, but the scientists now suggest that plants may also adapt their temperature in order to encourage pollination.

Lars Chittka and colleagues first showed that the bees were attracted to the warmer of two artificial feeders, particularly when the temperature difference was over four degrees Celsius. They were then exposed to artificial flowers of two different colours, one having a warmer temperature than the other, but each offering the same sugary reward. The bees preferred to land on the colour of flower that was at the warmer temperature. When flowers of the same colour were at different temperatures, the bees failed to discriminate between them, indicating that colour is acting as the cue that warmth is on offer.

The team believes their findings may have implications for the evolution of specific floral structures, and also for our understanding of the connection between sensory cues and pollinator behaviour.

Lars Chittka (Queen Mary, University of London, UK)
Tel: +44 207 882 3043; E-mail: [email protected]


[8] P2X receptors as cell-surface ATP sensors in health and disease (pp 527-532)

[9] Plant litter decomposition in a semi-arid ecosystem controlled by photodegradation (pp 555-558)

[10] Tumorigenic transformation by CPI-17 through inhibition of a merlin phosphatase (pp 576-579)

[11] Drying transition of confined water (p526)


***This paper will be published electronically on Nature's website on 02 August 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 03 August, but at a later date.***

[12] In situ structure of the complete Treponema primitia flagellar motor
DOI: 10.1038/nature05015


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.


Buenos Aires: 9

Vienna: 3


Hamilton: 5


Hong Kong: 10


Jena: 10


Ibaraki: 6

Osaka: 6

Tokyo: 6


Stellenbosch: 4


Cambridge: 7, 8

Hatfield: 1

Keele: 1

Leicester: 1

London: 7

Manchester: 8


Berkeley: 6

Los Angeles: 8
Pasadena: 12

Boston: 3
New Jersey

Princeton: 3
New Mexico

Albuquerque: 11

Los Alamos: 6
New York

Ithaca: 6


Madison: 2


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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: 02 Aug 2006

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