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This press release is copyright Nature. VOL.436 NO.7056 DATED 8 SEPTEMBER 2005
* Earth science: Evidence for large-scale soil carbon loss
* Diabetes: Opposite effects, but one target
* Astronomy: Slicing into Ceres
* Ecology: Rate of exchange determines evolutionary battle outcome
* Fluid mechanics: Walking oil droplets go into orbit
* Infectious disease: On the origin and size of infectious prions
* Infectious disease: The spiniest aspect of amyloid formation
* Palaeoclimate: Tropical connections
* ...And finally: Fin it to win it
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[1] Earth science: Evidence for large-scale soil carbon loss (pp245-248;
N&V)
Global warming could be causing soils to release carbon dioxide at a rate
that offsets the UK's reductions in fossil fuel emissions achieved in 2002
compared to 1990, according to research published in this week's Nature.
Guy Kirk and colleagues surveyed almost 6,000 sites around England and Wales
between 1978 and 2003, measuring how much carbon was locked into soils. They
found that carbon was being lost at an average rate of 0.6% per year. Soils
with higher carbon content lost their carbon at a higher rate. Extrapolating
to the entire UK, the researchers estimate annual losses of soil organic
carbon of 13 teragrams (13 Tg) of carbon per year (1 teragram = 1012 grams).
The losses appear to be happening irrespective of land use, suggesting a
link to climate change. There is no apparent single factor other than
climate change that could degrade non-agricultural soils.
"These losses thus completely offset the past technological achievements in
reducing CO2 emissions, putting the United Kingdom's success in reducing
greenhouse-gas emissions in a different light," comment E. Detlef Schulze
and Annette Freibauer in a related News and Views article.
CONTACT:
Guy J. D. Kirk (Cranfield University, Silsoe, UK)
Tel: +44 1525 863294; E-mail: [email protected]
E. Detlef Schulze (Max Planck Institute for Biochemistry, Jena, Germany)
Tel: +49 364 157 6100; E-mail: [email protected]
[2] Diabetes: Opposite effects, but one target (DOI: 10.1038/nature03967)
***This paper will be published electronically on Nature's website on 7
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 8 August, but at a later date.***
Scientists have identified a link between two major pathways that regulate
blood glucose levels, as published online this week by Nature. One
stimulates glucose production in the liver during fasting; the other causes
the liver to inhibit glucose production under stressful conditions and
during exercise.
Marc Montminy and colleagues found that both pathways act in an opposing way
on a common target - a protein called TORC2 that helps to switch on genes
that lead to glucose production in the liver. TORC2 must enter the nucleus
in order to act, and it turns out that the two pathways regulate the
activity of TORC2 by controlling its movement into the nucleus. Fasting
conditions cause a phosphate molecule to be removed from TORC2, which allows
it to enter the nucleus and switch on gluconeogenic genes. Under conditions
of stress and energy deprivation, TORC2 becomes phosphorylated and can't
enter the nucleus, so its function is inhibited.
The finding might eventually lead to therapeutic ways to enhance TORC2
phosphorylation to inhibit glucose formation in the liver, a process that is
excessively activated in people with type 2 diabetes, the authors say.
CONTACT:
Marc Montminy (Salk Institute for Biological Studies, La Jolla, CA, USA)
Tel: +1 858 453 4100 ext.1394; E-mail: [email protected]
[3] Astronomy: Slicing into Ceres (pp224-226)
1 Ceres, the largest member of the asteroid belt between Mars and Jupiter,
is divided into layers that may include icy mantles over a rocky core,
according to research published in this week's Nature.
Astronomers had previously thought that the composition of Ceres was the
same all the way through, because the spectrum of light it reflected
suggested that it had never been heated up enough to differentiate into a
crust, mantle and core.
Now Peter Thomas and colleagues have used the Hubble Space Telescope to take
another look at Ceres. It is almost spherical, suggesting that its shape it
controlled by gravity, and its rotation reveals that material is not evenly
distributed. The scientists suggest that NASA's Dawn mission, which will
orbit Ceres in 2015, could even find tectonic features similar to those seen
on some icy moons.
CONTACT:
Peter C. Thomas (Cornell University, Ithaca, NY, USA)
Tel: +1 607 255 5908; E-mail: [email protected]
[4] Ecology: Rate of exchange determines evolutionary battle outcomes
(pp253-256)
When fighting a battle, drafting in reinforcements is the key to success -
at least if you're a parasite. So says a study of an evolutionary 'arms
race' in which the parasites' rate of migration determines whether they gain
the upper hand over their hosts.
Angus Buckling and colleagues used a mathematical model and laboratory
cultures to study the evolution of a bacterium called Pseudomonas
fluorescens and a viral pathogen that infects and kills it. As they report
in this week's Nature, the relative migration rates of host and pathogen
determine which of the two is better adapted to the evolutionary battle.
Higher rates of pathogen migration will ensure a greater local supply of
new, potentially useful genes for invading the host, whereas higher rates of
host migration will have the same effect for defensive genes.
These findings may be relevant to the spread of human diseases, the authors
add. With increased global travel, human pathogens are increasingly likely
to be spread between populations, a trend that could make parasitic diseases
more difficult to confront in the future.
CONTACT:
Angus Buckling (University of Oxford, UK)
Tel: +44 1865 271100; E-mail: [email protected]
[5] Fluid mechanics: Walking oil droplets go into orbit (p208)
Vibrating a bath of fluid vertically can make droplets on the surface either
bounce or walk, depending on how strongly the bath is vibrated. A Brief
Communication in this week's Nature describes how waves from two walking
droplets can collide and cause them to orbit around one another like twin
stars.
A bouncing droplet will assume a horizontal walking motion when the size of
the vibration reaches a threshold just below the onset of the Faraday
instability. This instability makes a liquid surface spontaneously wavy,
with patterns of stripes or squares (you may have seen the effect on the
surface of a cup of tea when a lorry rattles past). Arezki Boudaoud and
colleagues explain the repertoire of tricks that can be performed by moving
droplets by considering the waves emanating from each. The wave from a
bouncing drop propels the droplet horizontally and turns it into a walker.
Similarly, the waves emitted by two droplets affect the horizontal speed of
each other: whether the droplets are repelled or attracted into circular
orbits depends on how they interact with the waves.
CONTACT:
Arezki Boudaoud (Laboratoire de Physique Statistique, Paris, France)
Tel: +33 1 44 32 34 46; E-mail: [email protected]
[6] & [7] Infectious disease: On the origin and size of infectious prions
(pp257-261 & 262-265)
Malformed prion proteins appear to be responsible for transmissible
spongiform encephalopathies such as Creutzfeldt-Jakob disease. Large
fibrillar deposits of these prions are found in the brain tissue of patients
with this type of illness, but whether these deposits also cause disease is
not clear. A study appearing in Nature now shows that smaller, non-fibrillar
clusters of between 14 to 28 prion molecules are by far the most infectious.
Byron Caughey and colleagues also reveal that groups of fewer than six such
molecules have essentially no infectivity. Attempts to alleviate symptoms by
destabilizing these large protein aggregates might make things worse by
producing smaller but more infectious particles. These findings might have
implications for the treatment of other afflictions such as Alzheimer's and
Parkinson's disease, also characterized by deposition of amyloid fibrils.
In the same issue, the origins of infectious prion 'seeds' in yeast
are explored in a paper by Tricia Serio and Prasanna Satpute-Krishnan. They
demonstrate that the conversion of the yeast protein Sup35 to its prion form
does not need to happen during the synthesis of Sup35 - mature and fully
functional molecules can readily join a prion seed. This remodelling of
mature protein is accompanied by the loss of its activity and therfore
causes immediate effects in the cell.
CONTACT:
Byron Caughey (NIAID/NIH Rocky Mountain Laboratories, Hamilton, MT, USA)
paper no: [6]
Tel: +1 406 363 9264; E-mail: [email protected]
Tricia R. Serio (Brown University, Providence, RI, USA) paper no: [7]
Tel: +1 401 863 1308; E-mail: [email protected]
[8] Infectious disease: The spiniest aspect of amyloid formation (pp266-269;
N&V)
Amyloid fibrils are found in a number of neurodegenerative disorders,
including Alzheimer's and prion-based diseases. These fibrils are rope-like
structures formed by linked protein molecules. David Eisenberg and his
colleagues report in this week's Nature how these proteins can "zip up"
without losing their ability to function properly.
The accepted paradigm has been that native proteins undergo wholesale
refolding into a generic amyloid structure. Using a 'designer' enzyme that
can form amyloids, Eisenberg and his team now show that this model might
need modifying. The enzyme simply opens, and the amyloid spine forms from
one segment of its polypeptide chain while the core of the protein remains
folded. The one polypeptide segment missing after opening can be
complemented - through a domain-swap with the neighbouring protein - to form
active enzyme again.
"Because of their large size and variable length, amyloid fibres confound
traditional methods used to determine protein structure. Sambashivan et al.
use an ingenious approach to show that the protein in the fibre has a native
structure," writes Andrew Miranker in a related News and Views piece.
CONTACT:
David Eisenberg (UCLA, Los Angeles, CA, USA)
Tel: +1 310 825 3754; E-mail: [email protected]
Andrew Miranker (Yale University, New Haven, CT, USA)
Tel: +1 203 432 8954; E-mail: [email protected]
[9] Palaeoclimate: Tropical connections (241-244)
In the warm greenhouse climate of the Cretaceous period, the tropical
marginal oceans responded extremely sensitively to periods of intense
rainfall and changes in river discharge. High river runoff caused oxygen
deprivation in these ancient seas, leaving its signature in the sediments as
black shales - layers extremely rich in organic matter - according to Thomas
Wagner and colleagues in this week's Nature.
The geochemical characteristics found in a sediment core off the Ivory Coast
tell the tale of the ancient connections between rainfall intensity and loss
of oxygen in the coastal ocean. Adding results from a climate model, Wagner
and colleagues find that a specific orbital constellation, when the Earth's
elliptical orbit took it closest to the Sun at the time of equinox,
coincided with periods of high river runoff that triggered the dramatic
ocean response.
CONTACT:
Thomas Wagner (University of Newcastle, Newcastle upon Tyne, UK)
Tel: +44 191 246 4880; E-mail: [email protected]
[10] ...And finally: Fin it to win it (pp207-208)
Fish fighting provokes a male hormonal response that is dependent on the
likely outcome of the contest, according to a Brief Communication in this
week's Nature. Rui F. Oliveira and colleagues show that a deadlock between
male cichlid fish (Oreochromis mossambicus) fails to trigger androgen
aggression hormones even after a vicious confrontation, suggesting that
androgens start to surge only when a fish's chances of winning look good.
The researchers kept cichlid fish in isolation for seven days and
then presented individuals with a mirror at one end of the tank. Fish do not
recognize their own reflection and treat it as an intruder, attacking it
with mounting aggression. However, the outcome of this contest is inevitably
a tie. The androgen levels of fish taking part in this virtual battle did
not change, and were comparable to those in control fish not exposed to
their mirror image.
The authors suggest this might be an adaptive mechanism that allows
individuals to mount a hormonal response and enhance their social status
once they have assessed the relative fighting ability of their challenger.
CONTACT:
Rui F. Oliveira (Instituto Superior de Psicologia Aplicada, Lisbon,
Portugal)
Tel: +351 218 811 700; E-mail: [email protected]
ALSO IN THIS ISSUE...
[11] Wave acceleration of electrons in the Van Allen radiation belts
(pp227-230)
[12] Verification of the Crooks fluctuation theorem and recovery of RNA
folding free energies (pp231-234; N&V)
[13] Ionic colloidal crystals of oppositely charged particles (pp235-240)
[14] Geophysical evidence from the MELT area for compositional controls
on oceanic plates (pp249-252)
[15] A mechanistic principle for proton pumping by cytochrome c oxidase
(pp286-289)
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.
FRANCE
Montpellier: 4
Orleans: 11
Paris: 5
GERMANY
Bremen: 9
Cologne: 9
Kiel: 9
JAPAN
Suita: 2
Tokyo: 13
Yokosuka: 14
THE NETHERLANDS
Utrecht: 13
PORTUGAL
Lisbon: 10
SPAIN
Barcelona: 12
SWEDEN
Stockholm: 15
UNITED KINGDOM
Cambridge: 11
Harpenden: 1
Oxford: 4
Silsoe: 1
UNITED STATES OF AMERICA
Arizona
Tucson: 3
California
Berkeley: 12
La Jolla: 2
Los Angeles: 3, 8, 11
Pasadena: 8
San Francisco: 14
Stanford: 11
Colorado
Boulder: 3, 11
Iowa
Iowa City: 11
Maryland
College Park: 3
Massachusetts
Woods Hole: 14
Minnesota
Minneapolis: 11
Montana
Hamilton: 6
New Mexico
Los Alamos: 12
New York
Ithaca: 3
Pennsylvania
North Wales: 12
Rhode Island
Providence: 7, 14
Tennessee
Memphis: 2
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