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Nature press release for 11th April 2002 issue

April 11, 2002

[416626] ECOLOGY: CLIMATE TO CHANGE WILDLIFE (pp626-629)

Climate change will rearrange natural communities, say researchers in this week's Nature. Their computer models of animals` shifting distributions in response to global warming show that the wild inhabitants of many areas may be radically different in 50 years time. The results also reveal the likely complexity of the effects of global warming - the assumption that everything will move either north or uphill is simplistic.
Ecologist A. Townsend Peterson of the University of Kansas, and colleagues used specimens in museums around the world to plot the geographical ranges of 1,870 Mexican species of mammal, bird and butterfly. The researchers then combined this with information on the environment of each location, matching each species to its preferred climate.
Next, powerful computer simulations calculated how the climate of each location would change over the next half-century, and so where each species would be able to survive. The researchers used two climate-change scenarios, and varied their assumptions about the dispersal powers of animals.
Relatively few species will go extinct altogether, they predict. But most will find themselves with smaller ranges in 2055 than now. And the greatest effects of climate change may come from this reshuffling of ecosystems, bringing new hosts and parasites, and predators and prey together.
CONTACT:
A Townsend Peterson tel +1 785 864 3926, e-mail town@ukans.edu

[416636] LIFELINES: ENZYME CLEARS BARRIER TO SPINAL CORD RECOVERY (pp636-640; N&V)

A bacterial enzyme that enables severed nerves to repair themselves is reported in this week`s Nature. It could form part of a future regimen for victims of spinal cord injury.
After damage to spinal cord tissue, a thicket of molecules is deposited that prevent nerve cells growing back into the scarred area.
Elizabeth Bradbury of King`s College London, and colleagues injected rats that had spinal cord injury with chondroitinase ABC, a bacterial enzyme that chews up one of the obstructing molecules. Severed nerves partially regenerated, and the animals regained near-normal walking behaviour.
In combination with strategies to overcome other inhibitory blocks, chondroitinase ABC could aid recovery from spinal cord injuries, says neuroscientist Lars Olson of the Karolinska Institute in Stockholm, Sweden. "Intense experimental work is beginning to suggest that they might one day be treatable," he says in an accompanying News and Views article.
CONTACT:
Elizabeth Bradbury tel +44 20 7848 6185, e-mail elizabeth.bradbury@kcl.ac.uk
Lars Olson tel + 46 8 728 70 50, e-mail Lars.Olson@neuro.ki.se


[416603] LIFELINES: AUTOIMMUNE ADVANCE (pp603-607; N&V)

Advances in understanding what stimulates autoantibodies to form and destroy tissues in lupus, rheumatoid arthritis and other systemic autoimmune diseases are announced in this week`s Nature. The findings should open new avenues for treatment.
Ann Marshak Rothstein of Boston University School of Medicine, Massachusetts, and colleagues reveal an unexpected mechanism that explains how immune cells might perceive antibodies as pathogens, provoking the production of autoantibodies. They show that activation of autoreactive B cells involves the co-engagement of the B-cell receptor and a Toll-like receptor (TLR9) by antibody/autoantigen immune complexes. This establishes that endogenous TLR ligands have a critical role in the aberrant activation of the adaptive immune system.
"This raises the possibility that the drug chloroquine, which inhibits TLR9-mediated signalling, may be effective in some patients with systemic autoimmune diseases," explain Carola G. Vinuesa and Christopher C. Goodnow of the Australian National University, Canberra, in an accompanying News and Views article. "Drugs that specifically target Toll-like-receptor signalling pathways could be promising new treatments for antibody-mediated autoimmune diseases or their complications," they conclude.
CONTACT:
Ann Marshak Rothstein tel +1 617 638 4299, e-mail amrothst@bu.edu
Christopher C. Goodnow tel +61 2 6125 3621, e-mail chris.goodnow@anu.edu.au


[416617] EARTH: AMAZON RIVERS AWASH WITH CO2 (pp617-620; N&V)

The vast rivers and wetlands of South America`s Amazon rainforest may release as much as 0.5 billion tonnes of carbon, in the form of carbon dioxide, into the atmosphere every year. This new-found source of CO2 - the most important man-made greenhouse gas - suggests that tropical forests are neither a source nor a sink for CO2.
Defining the components of the carbon cycle is crucial to understanding how best to regulate greenhouse gases, but the role of tropical forests is elusive. On-the-ground measurements of CO2 emissions from upland Amazon forests suggest that they take up more CO2 than they put out. But global measurements of CO2 in the atmosphere suggest that the Amazon is almost in balance, releasing as much - if not more - carbon as it absorbs. Carbon-cycle researchers were beginning to wonder whether one of these measurements was wrong.
In a Letter to this week`s Nature, Jeffrey Richey of the University of Washington in Seattle, and colleagues identify a new carbon source that could help to balance the Amazon`s carbon books. They find that in the rivers and wetlands, plant material washed down from the forests gets broken down by microbes, and its carbon escapes to the atmosphere as CO2. If the process occurs throughout the tropics, it may parallel the amount of CO2 released by deforestation. John Grace and Yadvinder Malhi at the University of Edinburgh, UK, comment on the research in an accompanying News and Views article.
CONTACT:
Jeffrey E. Richey tel +1 206 543 7339, e-mail jrichey@u.washington.edu
John Grace tel +44 131 650 5430, e-mail jgrace@ed.ac.uk
Yadvinder Malhi tel +44 131 650 5744, email ymahli@srv0.bio.edinburgh.ac.uk


[416576] LIFELINES: SECOND GREEN REVOLUTION (pp576-578)

Feeding the world in the twenty-first century could require a second Green Revolution. That may involve the most ambitious feat of genetic engineering yet attempted, reports a News Feature in this week`s Nature: re-engineering rice at the biochemical level.
Global production of rice, the world's most important staple crop, has risen threefold over the past three decades. If similar progress could be maintained, population growth need not outstrip food production. But yields are fast approaching the limit set by the crop's efficiency in harvesting sunlight and using its energy to make carbohydrates. The News Feature reveals how plant scientists are trying to alter that limit, by re-engineering both the biochemistry and anatomy of rice.


[416620] EARTH: TIME TO REVERSE POLARITY? (pp620-623; N&V)

In this week`s Nature, satellite measurements of the Earth's magnetic field reveal a detailed picture of the circulation in the liquid iron core. The data suggest that the planet could be in the early stages of reversing its magnetic polarity.
Comparing recent data from the Danish Oersted satellite and data collected by the MAGSAT satellite 20 years ago, Gauthier Hulot of the Institut de Physique du Globe de Paris and colleagues have spotted patches of reversed magnetic flux concentrated in two regions on the core-mantle boundary. In the largest patch, beneath the southern tip of Africa, the magnetic field points towards the centre of the Earth, opposite to the normally outward-pointing field of the Southern Hemisphere. The team find another concentration of reversed-flux patches around the North Pole. Growth and pole-ward migration of the reversed-flux patches can, they say, account for almost all of the decrease in the dipole field in the past 150 years.
"The results confirm some long-held tenets of dynamo theory - but contradict others," says Peter Olson of Johns Hopkins University, Baltimore, Maryland, in an accompanying News and Views article. "Combining data from satellite missions with measurements of the palaeomagnetic field recorded in lava and sediments could extend our picture of the geodynamo over thousands, even millions, of years into the past," he concludes.
CONTACT:
Gauthier Hulot tel +33 1 44 27 24 12, e-mail gh@ipgp.jussieu.fr
Peter Olson tel +1 410 516 7707, e-mail olson@jhu.edu


[416581] ECOLOGY: LAND USE QUESTIONED (p581)

A contribution to the Correspondence page in this week's Nature raises doubts over the common assumption that countries with higher incomes demand much more land per person to sustain high consumption rates.
Stephen Budiansky of Black Sheep Farm, Leesburg, Virginia, presents land-use statistics from the US Department of Agriculture, revealing that developed nations provide more calories per person, and considerably more meat and dairy products, while using only slightly more crop land per capita than the poorest countries and less total agricultural land. Intensive farming such as use of chemical fertilizers and high-yielding grain varieties requires less land to feed more people.
CONTACT:
Stephen Budiansky tel +1 703 777 7640, e-mail stephen@budiansky.com


[416599] AND FINALLY: BUG DROOL PACIFIES PLANTS (pp599-600)

It`s well known that blood-sucking insects circumvent their victim`s defences by injecting them with saliva to prevent blood from clotting. Conversely, insects feeding on leaves were thought to have no means to counterattack the plant`s defensive secretions stimulated by their munching.
In a Brief Communication to this week`s Nature, Gary Felton at Pennsylvania State University in University Park, and colleagues show that for the corn earworm (Helicoverpa zea) caterpillar feeding on tobacco plants, this is not quite the whole story. Felton`s team show that an enzyme in the saliva of H. zea neutralizes nicotine, the primary defensive molecule of tobacco plants. They found that leaves attacked by H. zea with defective salivary glands contained more nicotine than those fed on by normal caterpillars, suggesting that the saliva suppresses the production of toxic nicotine that is ordinarily induced by feeding.
CONTACT:
Gary Felton tel +1 814 863 7789, e-mail gwf10@psu.edu

ALSO IN THIS ISSUE

 Scaling of entanglement close to a quantum phase transition

 Spontaneous breaking of time-reversal symmetry in the pseudogap state of a high-Tc superconductor

 Optical studies of solid hydrogen to 320 GPa and evidence for black hydrogen

 Strong male-driven evolution of DNA sequences in humans and apes

 Extraction of a weak climatic signal by an ecosystem

 Direct visuomotor transformations for reaching

 Dissecting glucose signalling with diversity-orientated synthesis and small-molecule microarrays

 A 'periodic table' for protein structures

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