Birds fall behind with breeding; Searching for ozone layer recovery; How fast does Saturn spin?; Worms prove fertile drug testing ground; Reduction in tropical Pacific air circulation; Molecular devices you can rely on;

Summaries of newsworthy papers from Nature. VOL.441 NO.7089 DATED 04 MAY 2006

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This press release is copyright Nature. VOL.441 NO.7089 DATED 04 MAY 2006

This press release contains:

· Summaries of newsworthy papers:

- Climate change: Birds fall behind with breeding
- Atmospheric science: Searching for ozone layer recovery
- Planetary science: How fast does Saturn spin?
- Drug discovery: Worms prove fertile drug testing ground
- Climatology: Reduction in tropical Pacific air circulation
- Microelectronics: Molecular devices you can rely on

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

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[1] Climate change: Birds fall behind with breeding (pp 81-83)

Climate change is leading birds to breed during periods of food shortages, causing population declines, reports a paper in this week's Nature. The study, on the migratory pied flycatcher Ficedula hypoleuca, reports a large drop in bird population when of prey and predator species vary in the rate at which they adapt to warmer temperatures.

The pied flycatcher is a long-distance migratory bird. It spends the spring breeding in the Netherlands, where caterpillars make up the bulk of its chicks’ diet. Both and colleagues now look at the effects that earlier peaks in the caterpillar population, induced by warmer temperatures, have on the birds. The authors show that pied flycatcher populations have declined by approximately 90% in areas with the earliest food peaks, compared to 10% in areas with the latest food peaks. They attribute this decline to the birds breeding in periods when food is scarce.

The authors suggest that this mistiming is a result of the inability of the birds to adapt their rigid migratory journey to warmer temperatures. The populations of other long-distance migrants could suffer similar effects.

CONTACT
Christiaan C Both (Groningen University, Haren, Netherlands)
Tel: +31 50 363 2235; E-mail: [email protected]

[4] Atmospheric science: Searching for ozone layer recovery (pp 39-45)

International agreements to stop using ozone-destroying chemicals are having an effect; there are tentative signs that the condition of the ozone layer is now improving. But it seems unlikely that atmospheric ozone abundances will stabilize at levels observed before 1980, when ozone depletion was first observed.

Owing to high natural variability in ozone abundances, it is difficult to interpret the observation that ozone levels stopped declining in recent years, as the expected recovery (which is likely to take decades) is still in its initial phases. And given the changing conditions of the atmospheric environment, it is likely that ozone concentrations will stabilize at a different level to those observed before 1980 - it could end up being higher or lower. These recent developments are summarized in a Review Article in this week's Nature by Elizabeth C. Weatherhead and Signe Bech Andersen.

The Montreal Protocol has reduced the production and use of ozone-depleting substances since 1989. It has been lauded as a success in the wake of recent studies suggesting that the total ozone abundance has not decreased over the past eight years for most of the world. But there is a high natural variability in ozone concentration, the authors warn, and other anthropogenic atmospheric changes, such as rising temperatures, could dominate these recent changes - the real benefits of banning certain refrigerant and aerosol gases will only become apparent as the recovery continues.

Because of such changes in atmospheric conditions, it is likely that ozone abundances will stabilize at a different level from that observed before 1980. More observations through to the end of this decade are needed to help understand the link between ozone and temperature, say Weatherhead and Andersen.

CONTACT
Elizabeth Weatherhead (University of Colorado, Boulder, CO, USA)
Tel: +1 303 497 6653; E-mail: [email protected]

[5] Planetary science: How fast does Saturn spin? (pp 62-64; N&V)

Saturn's surface is shrouded beneath kilometres of thick and relatively featureless cloud, so astronomers have been uncertain about exactly how fast the giant planet rotates. But in this week's Nature, Giacomo Giampieri and colleagues report a periodicity in its magnetic field suggesting that the planet rotates once every 10 hours, 47 minutes and 6 seconds — give or take 40 seconds.

Previous measurements of varying radio emissions from the planet have yielded estimates of the rotation period of between 10 hours, 39 minutes 22 seconds and 10 hours 45 minutes 45 seconds.

But now the Cassini space probe has directly measured subtle changes in Saturn's magnetic field over a period of 14 months that are probably linked to the planet's rotation.

The improved estimate may help astronomers to determine the extent of the planet's distortion as it spins, and the scale of its suspected rocky core, comments David J. Stevenson in a related News and Views article.

CONTACT
Giacomo Giampieri (Jet Propulsion Laboratory, Pasadena, CA, USA)
Tel: +1 818 393 6385; E-mail: [email protected]

David J. Stevenson (California Institute of Technology, Pasadena, CA, USA)
Tel: +1 626 395 6534; E-mail: [email protected]

[6] Drug discovery: Worms prove fertile drug testing ground (pp 91-95)

This week's Nature shows that the experimental worm Caenorhabditis elegans is remarkably useful for identifying new potential drugs and revealing how they work.

Peter Roy and his colleagues exposed worms to 14,100 small molecules and identified 308 that triggered death or caused defects in growth, movement or morphology. They focused on one compound they named nemadipine-A, which resembles a class of widely prescribed anti-hypertension drugs called the 1,4-dihydropyridines (DHPs) that were known to bind to a subunit of certain calcium channels.

To work out what the protein target of nemadipine-A does in vivo, the team screened 180,000 mutant worms to find a gene that could suppress the effects of the drug. By doing this, they showed that the small molecule acts via a gene called egl-19, which is also a calcium channel subunit. The authors propose that additional genetic screens using the worm could reveal how the clinically important DHPs interact with the calcium channel in vivo, and this 'proof of principle' demonstration indicates that C. elegans can be used to rapidly identify new small-molecule tools and find their physiologically relevant protein targets.

CONTACT
Peter Roy (University of Toronto, ON Canada)
Tel: +1 416 946 8395; E-mail: [email protected]

[7] Climatology: Reduction in tropical Pacific air circulation (pp 73-76)

The strength of the mean tropical atmospheric circulation across the tropical Pacific Ocean has reduced, researchers report in this week's Nature, and this may affect the equatorial Pacific Ocean.

Gabriel A. Vecchi and colleagues used sea-level pressure observations since the mid-nineteenth century and modelling to reconstruct the intensity of the Walker circulation — the large-scale, east–west overturning of air across the equatorial Pacific — which they confirm has reduced in line with theoretical predictions about the impact of global warming. Climate model experiments further allowed them to attribute the observed change largely to anthropogenic forcing.

The modelling experiments also indicate that the slowdown in atmospheric circulation may drive a response in tropical Pacific Ocean circulation. Weaker wind stress may reduce the strength of ocean surface currents, shift subsurface currents, and damp down the upwelling of nutrient-rich water at the Equator. This may lead to a possible reduction of biological productivity under global warming, the authors suggest.

CONTACT
Gabriel Vecchi (National Oceanic and Atmospheric Administration, Princeton, NJ, USA)
Tel: +1 609 452 6583; E-mail: [email protected]

[8] Microelectronics: Molecular devices you can rely on (pp 69-72)

A technique for making molecular electronics devices with consistent, reliable and stable properties is presented in this week's Nature. The idea of making electronic devices from individual organic molecules, rather than from conventional metals and semiconductors, was first proposed in the 1970s. But researchers have struggled to produce devices that are dependable.

Bert de Boer and colleagues present a technique for making well-defined molecular junctions, in which organic layers one molecule thick bridge the gap between two metal electrodes. They suggest that their approach is simple, cheap, easy to integrate into standard chip fabrication methods, and "could pave the way for practical molecular electronics."

Many attempts to make molecular electronic devices make use of 'self-assembled monolayers', which are films of organic molecules just one molecule thick. When researchers tried previously to use these molecular films to create devices such as diodes, they found that the electrical properties vary widely, often with poor electrical contact between the molecules and the electrodes adjoining them.

The team overcome this problem of creating a good contact with the metal electrodes by introducing two innovations. First, they deposit the self-assembled monolayer within a microscopic cylindrical pore that penetrates an insulating plastic film, exposing a gold electrode beneath. This protects the molecular film, which stays stable for months. And the researchers ensure a good contact with the top electrode by first covering the molecular film with a thin layer of an electrically conducting polymer, acting as a kind of soft cushion as well as blocking off any intruding metal filaments.

CONTACT
Bert de Boer (University of Groningen, Netherlands)
Tel: +31 50 3634370; E-mail: [email protected]

ALSO IN THIS ISSUE…

[11] Testing the genetics underlying the co-evolution of mate choice and ornament in the wild (pp 84-86)

[12] A distal enhancer and an ultraconserved exon are derived from a novel retroposon (pp 87-90)

[13] Downstream nuclear events in brassinosteroid signalling (pp 96-100)

[14] The depolymerizing kinesin MCAK uses lattice diffusion to rapidly target microtubule ends (pp 115-119)

[15] Complex call production in the túngara frog (p 38)

ADVANCE ONLINE PUBLICATION

***This paper will be published electronically on Nature's website on 3 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 4 May, but at a later date.***

[16] Rec8 phosphorylation and recombination promote the step-wise loss of cohesins in meiosis DOI: 10.1038/nature04794

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.

BRASIL
Sao Paolo: 15

CANADA
Toronto: 6

CHINA
Beijing: 10

DENMARK
Copenhagen: 4

FINLAND
Helsinki: 11

GERMANY
Dresden: 14

KOREA
Busan: 9
Seoul: 2
Suwon: 9
Taejon: 3

NETHERLANDS
Eindhoven: 8
Groningen: 8
Haren: 1
Heteren: 1

PANAMA
Babloa: 15

RUSSIA
Moscow: 14

SWEDEN
Uppsala: 11

UNITED KINGDOM
London: 5
Oxford: 1

UNITED STATES OF AMERICA
California
Berkeley: 12
La Jolla: 13
Los Angeles: 2, 5, 15
Pasadena: 2, 5
Santa Barbara: 9
Santa Cruz: 12
Walnut Creek: 12
Colorado
Boulder: 4
Florida
Miami: 7
Massachusetts
Cambridge: 16
New Jersey
Princeton: 7
Union: 10
New York
Ithaca: 12
Texas
Austin: 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
Rinoko Asami, Nature Tokyo
Tel: +81 3 3267 8751; E-mail: [email protected]

For the UK/Europe/other countries not listed above
Ruth Francis, Nature London
Tel: +44 20 7843 4562; E-mail [email protected]

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Published: 03 May 2006

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