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This press release is copyright Nature.
VOL.439 NO.7077 DATED 9 FEBRUARY 2006
This press release contains:
* Summaries of newsworthy papers:
* Climate-biosphere interactions: Snow makes forests better carbon sponges
* Evolution: Sympatric speciation finally seen in action
* Materials: rusty revelations
* Solid state physics: A narrow shave for silicon
* Molecular biology: Hyperactive sperm undressed
* Astronomy: Gamma glow in Milky Way's heart reveals cosmic ray battering
* Mention of papers to be published at the same time with the same embargo
* Geographical listing of authors
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[2] Climate-biosphere interactions: Snow makes forests better carbon sponges (pp 711-714)
A source of negative feedback between climate and the biosphere that may
mitigate rather than exacerbate change is reported in this week's Nature.
Many of the relationships known to exist between climate change and global
ecosystems serve only to make matters worse: warming causes more warming.
Here Russell Monson and colleagues report that the amount of carbon dioxide
- the major greenhouse gas - released into the atmosphere from temperate
forests during winter decreases when there is less snow on the ground. Over
the course of a year, forests are net sinks of carbon dioxide: they take up
more than they release, thanks to photosynthesis and plant growth. But some
of the carbon dioxide taken up by forests during the growing season is
released again by the respiration of soil micro-organisms in the winter.
Snow covers the soil in a thermally insulating blanket, and the greater
warmth increases the rate of respiration. If there is less snow, there is
less respiration and thus should be less release of carbon dioxide. Monson
and colleagues have made measurements of temperature, snow cover and soil
respiration in a forest in the Rocky Mountains that verify this. Thus, in
cases where warmer winters lead to less snow, the net amount of carbon
dioxide absorbed by the forest ecosystem over the annual cycle is greater.
CONTACT
Russell Monson (University of Colorado, Boulder, CO, USA)
Tel: +1 303 492 6319; E-mail: [email protected]
[3] & [4] Evolution: Sympatric speciation finally seen in action
(DOI:10.1038/nature04566 and pp 719-723)
***Paper [3] will be published electronically on Nature's website on 8
February 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 9 February, but at a later date.***
Evolutionary experts have found two of the best examples yet for cases of
sympatric speciation, which is when two species diverge from a single
ancestor without geographical isolation. This issue has been a bone of
contention among evolutionists: many suspect that such speciation is
possible, but it has been fiendishly difficult to prove.
Botanist Vincent Savolainen and his colleagues offer convincing evidence in
the form of two sister species of palm tree on Lord Howe Island, a remote
outpost almost 600 kilometres off the eastern coast of Australia. As they
report in a study published online by Nature, genetic studies of the two
species show that they are indeed sisters, and diverged much more recently
than the island's creation. This shows that the two species have always
lived side by side, making their speciation almost certainly sympatric, the
authors explain. Species generally diverge when they become reproductively
isolated - usually through geographical isolation (giving rise to allopatric
speciation). But here the two species seem to have diverged after they began
flowering at different times of year, probably as a result of differing soil
preferences.
Meanwhile, in another Nature paper this week, zoologists led by Axel Meyer
report on two species of fish species in crater Lake Apoyo in Nicaragua that
also seem to have diverged sympatrically. The lake is just 5 kilometres
across and less than 23,000 years old, but DNA profiling shows that, during
that time, it was colonized by the species Amphilophus citrinellus, which
quickly spawned a daughter species, A. zaliosus.
CONTACT
Vincent Savolainen (Royal Botanic Gardens, Kew, Richmond, UK) Paper [3]
E-mail: [email protected] (currently available by email only)
OR
Bill Baker (Royal Botanic Gardens, Kew, Richmond, UK) Co-author
Tel: +44 20 8332 5224; E-mail: [email protected]
Axel Meyer (University of Konstanz, Konstanz, Germany) Paper [4]
Tel: +49 7531 88 3069; E-mail: [email protected]
[5] Materials: rusty revelations (pp 707-710)
Researchers have shed light on atomic-scale changes that take place during
the initial stages of electrochemical corrosion, as reported in a paper in
this week's Nature.
Frank Renner and colleagues studied the structural and chemical changes
arising from the electrochemical degradation of a single crystal of a
copper-gold alloy when placed in sulphuric acid. The team obtained
high-resolution data by using synchrotron light to achieve X-ray
diffraction. They uncover the mechanism underlying a mysterious but widely
observed passivation phenomenon, whereby a protective layer against further
corrosion is formed. By further increasing the potential applied to the
alloy, the protective layer is disrupted and gold 'islands' are formed,
which act as platforms for the growth of porous gold.
Corrosion currently destroys more than three per cent of the world's
GDP. These new insights can be applied to a variety of different alloys used
in corrosive environments and to materials that could exploit such
degradation to form porous metals of technological interest.
CONTACT
Frank Renner (European Synchrotron Radiation Facility, Grenoble, France)
Tel: +33 476 88 2722; E-mail: [email protected]
[6] Solid state physics: A narrow shave for silicon (pp 703-706; N&V)
Good news this week for the future of microelectronics. Max Lagally and
colleagues report in Nature that as films of silicon get thinner and
thinner, they don't necessarily lose their electrical conductivity. The
researchers conclude that electronic devices made from even the thinnest
slabs of silicon ought to function properly.
These wafer-thin sheets of silicon are becoming increasingly common in
so-called silicon-on-insulator (SOI) technology, in which electrically
conducting silicon films are laid down on top of a thick slab of insulating
silicon dioxide (silica). SOI devices are at the cutting edge of
microelectronics, and improving them often entails making the silicon films
ever thinner. But researchers have worried that in extremely thin films,
imperfections at the interface of silicon and silica will trap the mobile
charged particles (charge carriers) that are responsible for electrical
current, impairing the ability of a current to pass through the device.
Lagally and colleagues show that this isn't so. Their microscopic
inspections of ultra-thin silicon layers and measurements of conductivity
show that the atoms at the surfaces of the layer are rearranged relative to
the interior, and that this feeds charge carriers into the rest of the
silicon film, retaining its conductivity.
CONTACT
Max Lagally (University of Wisconsin-Madison, Madison, WI, USA)
Tel: +1 608 263 2078; E-mail: [email protected]
John Boland (Trinity College Dublin, Dublin, Ireland)
Tel: +353 1 608 3140; E-mail: [email protected] <mailto:[email protected]>
[7] Molecular biology: Hyperactive sperm undressed (pp 737-740)
The trigger for an increase in calcium levels in the tails of sperm, which
causes them to become hyperactivated, is revealed in new research published
in Nature this week. This hyperactivation is a key mechanism for male
fertility.
David E. Clapham and colleagues used mouse studies to identify that the
protein CatSper1, specifically localized in the sperm tail (or flagella), is
a key component in the flagellar calcium channel. They show that
intracellular alkalinization drives CatSper current to increase calcium in
the flagella and thus induce sperm hyperactivation.
Hyperactivation is the change in movement pattern - from symmetrical small
movements to whip-like asymmetric tail beating - that mammalian sperm
undergo in order to penetrate the egg and hence overcome barriers to
fertilization. Although it had previously been established that
hyperactivation requires an increase in calcium in flagella, probably
involving ion channels, little was known about the specific mechanisms
triggering this increase in calcium.
CONTACT
David Clapham (Harvard Medical School, Boston, MA, USA)
Tel: +1 617 919 2680; E-mail: [email protected]
[8] Astronomy: Gamma glow in Milky Way's heart reveals cosmic ray battering
(pp 695-698)
Giant clouds of hydrogen gas at the centre of the Milky Way are glowing as
they emit very high-energy gamma rays, the telltale signature of bombardment
by cosmic rays.
In this week's Nature, Jim Hinton and colleagues using the High Energy
Stereoscopic System (HESS) telescopes calculate that the glow is most
probably consists of highly energetic particles that are either fragments of
atomic nuclei or protons (the nucleus of a hydrogen atom) that have been
accelerated to incredible speeds by Galactic cosmic rays.
Although the source of these Galactic cosmic rays is unclear, it is widely
believed that they originate in the shockwaves of expanding supernova
remnants. The scientists estimate that the cosmic rays may have been
accelerated in a supernova explosion that happened about 10,000 years ago,
providing the first direct evidence for recently accelerated cosmic rays
containing protons in any part of our Galaxy.
An alternative explanation is that the cosmic rays were accelerated as they
swung round the supermassive black hole, Sagittarius A*, that is suspected
to be at the centre of our Galaxy.
CONTACT
Jim Hinton (Max-Planck Institute for Nuclear Physics, Heidelberg, Germany)
Tel: +49 6221 516279; E-mail: [email protected]
ALSO IN THIS ISSUE...
[10] Palaeo-altimetry of the late Eocene to Miocene Lunpola
basin, central Tibet (pp 677-681; N&V)
[11] Anti-planetward auroral electron beams at Saturn (pp 699-702)
[12] Localized maternal orthodenticle patterns anterior and posterior in
the long germ wasp Nasonia (pp 728-732)
[13] Molecular characterization of Ph1 as a major chromosome pairing
locus in polyploid wheat (pp 749-752)
[14] ClpS is an essential component of the N-end rule pathway in
Escherichia coli (pp 753-756)
ADVANCE ONLINE PUBLICATION
***This paper will be published electronically on Nature's website on X 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 X, but at a later date.***
[15] Atomic structure of a Na1- and K1-conducting channel
(DOI:10.1038/nature04508)
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.
ARMENIA
Yerevan: 8
AUSTRALIA
Lord Howe Island: 3
CANADA
Drumheller: 1
CHINA
Beijing: 1
CZECH REPUBLIC
Prague: 8
DENMARK
Aarhus: 3
FRANCE
Gif-sur-Yvette: 8
Grenoble: 5, 8
Meudon: 8
Montpellier: 3,8
Palaiseau: 8
Paris: 8
Toulouse: 8
GERMANY
Berlin: 8, 14
Bochum: 8
Hamburg: 8
Heidelberg: 8, 14
Kattenburg-Lindau: 11
Koln: 11
Konstanz: 4
Stuttgart: 5
Ulm: 5
Witten: 14
IRELAND
Dublin: 8
NAMIBIA
Windhoek: 8
SOUTH AFRICA
Potchefstroom: 8
SWITZERLAND
Lausanne: 3
UNITED KINGDOM
Durham: 8
Exeter: 9
London: 11
Norwich: 13
Reading: 9
Richmond: 3
UNITED STATES OF AMERICA
California
Livermore: 9
Los Angeles: 11
San Diego: 2
Colorado
Boulder: 2, 9
District of Columbia
Washington DC: 1
Florida
Tallahassee: 1
Illinois
Chicago: 10
Maryland
Laurel: 11
Massachusetts
Boston: 7
Peabody: 6
New York
New York: 1, 12
Stony Brook: 1
Ohio
Oxford: 10
South Dakota
Sioux Falls: 13
Texas
Dallas: 15
Washington
Bellingham: 12
Wisconsin
Madison: 6
PRESS CONTACTS...
For North America and Canada
Katie McGoldrick, Nature Washington
Tel: +1 202 737 2355; E-mail: [email protected]
<mailto:[email protected]>
For Japan, Korea, China, Singapore and Taiwan
Rinoko Asami, Nature Tokyo
Tel: +81 3 3267 8751; E-mail: [email protected]
<mailto:[email protected]>
For the UK/Europe/other countries not listed above
Ruth Francis, Nature London
Tel: +44 20 7843 4562; E-mail [email protected]
<mailto:[email protected]>
Zoe Corbyn, Nature London
Tel: +44 20 7843 4658; E-mail: [email protected]
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