The composition of the Amazon rainforest is changing even in areas not directly affected by human activities such as logging or burning. Large, fast-growing trees are increasingly dominating their slower-growing neighbours, according to a study in this week's Nature.
The change may be due to increasing levels of carbon dioxide in the atmosphere, speculate William Laurance and colleagues. Plant growth requires carbon dioxide, so increased levels over the past two decades may have allowed fast-growing species to gain the upper hand over their rivals.
The changing composition of supposedly pristine rainforest could exacerbate global warming, the authors warn. Rainforests are thought to limit the greenhouse effect by storing carbon in their tissues, thus reducing the amount of carbon dioxide in the atmosphere. But fast-growing trees are less densely wooded than slow-growing ones, and may therefore sequester less carbon.
[2] Fertility: Mouse ovaries boast hidden reserves (pp145-150; N&V)
The long-held view that female mammals are born with their lifetime's complement of egg cells may not be correct after all. Research published in this week's Nature shows that female mice continue to produce new egg cells after birth, casting doubt on a theory that has persisted for more than half a century.
The discovery hints that women, like men, may continue to replenish their reproductive cells during life, say Jonathan Tilly and colleagues. The researchers treated prepubertal female mice with a chemical that kills egg cells, and found that the mice still produced viable eggs in adulthood, showing that they can generate fresh eggs to replace damaged ones.
If the same process occurs in humans, it may shed light on why women's fertility declines after 30, says Allan Spradling in an accompanying News and Views article. Experts had previously been puzzled as to why eggs would begin to fail after 30 years instead of, say, 40 or 50. The new study suggests that this might be due to depletion of these 'replacement' reproductive cells, rather than defects in egg cells produced before birth.
[3] Particle physics: Have we discovered the Higgs boson? (pp141-144)
Maybe, according to a Progress Article in this week's Nature.
The Higgs boson is a subatomic particle that physicists believe gives mass to all the other particles that make up matter. The only problem is that no one has ever seen a Higgs boson — it is the last undiscovered component of the 'standard model' of particle physics.
Physicists have been smashing tiny particles together in machines such as the Large Electron Positron collider, in order to squeeze out and detect a Higgs particle. Other research has looked for the Higgs indirectly — some particles can momentarily spit out a Higgs boson, becoming lighter in the process. Measuring that particle's mass can then give clues about the mass of the Higgs boson itself.
In a summary of the hunt so far, Peter Renton points out the conflicting results that have prevented scientists from pinning down the precise mass of the elusive particle. But according to Renton, the Large Hadron Collider that will begin operating in 2007 at CERN (European Organisation for Nuclear Research at Geneva, Switzerland) should resolve the mystery of whether the Higgs boson exists.
[4] Health and Medicine: Cell double act boosts blood vessel production (pp138-139)
Researchers have devised a new way to make long-lasting, functional blood vessels in mice. The method, described in a Brief Communication in this week's Nature, may help those who wish to produce artificial vascular networks for human use.
Rakesh K. Jain and colleagues cultured two types of cell together inside a three-dimensional fibre gel — lining cells from human umbilical vein were grown with mesenchymal precursor cells, which are able to develop into connective tissue and blood vessels. The vascular networks were then implanted into mice, where they survived for around a year.
The lining cells formed a network of long, branching tubes, which connected with the mouse's own circulatory system and became filled with blood. The mesenchymal cells became incorporated into the vessel walls.
Together, the two cell types give the network added stability, the authors say. When lining cells are grafted alone, they fail within around 60 days. The technique also reduces the need for genetic modification. In the past, researchers have inserted genes into vascular cells to enhance their survival, but this can make them unstable and may trigger cancerous changes, the authors point out.
[5] Physics: Flying qubits! (pp153-157; N&V)
Scientists have demonstrated that quantum information can be shared between stationary atoms and free-flying photons. The research, published in this week's Nature, is an important milestone in the quest to build a quantum computer that processes information using quantum states, potentially operating much faster than conventional computers.
B. B. Blinov and colleagues are the first to directly observe atom"photon entanglement, where the particles are physically separated but share unique properties. Photons are packets of light, so a device might use an atom to store a 'memory', while the photon carries that information to a distant receiver.
These bits of quantum information — or 'qubits' — could potentially travel over many kilometres, according to Eugene Polzik, writing in an accompanying News and Views article. "Ultimately a quantum link over a very long distance could be created," he says.
[6] Vaccine research: New smallpox inoculations show promise (pp182-185)
Tests of an experimental smallpox vaccine have produced encouraging results in monkeys and mice. The discovery may lead to an alternative for humans unable to receive current smallpox vaccines. Monkeys treated with modified vaccinia virus Ankara (MVA) were immune to monkeypox, which is similar to smallpox in humans, report Bernard Moss and colleagues in this week's Nature. Monkeys that did not receive the treatment became severely ill after being exposed to monkeypox.
Monkeys were most resistant to the disease when treated with MVA and then with the existing smallpox vaccine Dryvax, the authors report. This suggests that MVA could be used as a 'prevaccine', to which Dryvax could be added in the event of a specific smallpox threat, or as an alternative for those unable to take the existing vaccine for medical reasons.
In a separate study (with the same embargo and also to be found on the Nature press site) published in Proceedings of the National Academy of Sciences, Moss's team administered MVA and Dryvax to immunocompromised mice. Dryvax inoculations led to severe weight loss, skin sores, and eventual death. However, immunocompromised mice remained healthy even when treated with 1,000 times as much MVA.
The authors report that both MVA and Dryvax vaccinations led to similar levels of poxvirus immunity in healthy mice. Furthermore, MVA protected mice with specific immune deficiencies. These results suggest that MVA could be a suitable replacement for Dryvax in immunocompromised humans.
[7] Planetary science: Tilted poles explained (pp151-153; N&V)
The mystery of why the magnetic fields of Uranus and Neptune are tipped over may have been solved by research published in this week's Nature.
Earth, along with Jupiter and Saturn, has a magnetic field that points in roughly the same direction as the planet's axis of rotation. This is why our magnetic north pole is close to the geographical North Pole. But on Uranus and Neptune, the poles are tilted so that magnetic north lies much closer to the equator.
Sabine Stanley and Jeremy Bloxham claim that the circulating metallic fluid inside Uranus and Neptune that generates their magnetic fields is restricted to a thin shell in the planet's interior. Their theory predicts magnetic fields that are very similar to those observed by NASA's Voyager 2 probe.
In an accompanying News and Views article, Jonathan Aurnou says, "Their model clearly and impressively demonstrates that the same fundamental process can explain the basic structure of all the dynamo-generated planetary magnetic fields presently observed in the solar system".
China's Science and Technology: Views from the West
China's economy is booming. The success is due in part to the natural entrepreneurship of Chinese people, but also to their dedicated pursuit of new technologies. A supplement in this week's Nature explores the country's scientific prowess and potential.
In recent years, China has invested significantly in nanotechnology and biotechnology. But turning research into profits can be challenging, caution James C. Hsiao and Kenneth Fong. Good management, product design, a market drive and alternative sources of cash can all help to smooth the transition.
With appropriate funding and support, China could take the lead in other areas. The country's liberal views on human embryo technology could place it at the forefront of human stem cell research, says Xiangzhong Yang.
But despite its potential, China's scientific output remains low. The reasons may be cultural, argues Mu-ming Poo. Political conformity may be stifling scientific creativity. This may be compounded by the country's education system and inadequacies in peer review for funding, says Ray Wu. Teachers may not be encouraging critical thinking, he says. Researchers need training in scientific thinking, priority setting, problem solving and communication skills, says Alice Shih-hou Huang. Only then will they find themselves able to compete in the international scientific arena.
Collaborative projects will also help to boost China's scientific standing, say Kenneth Chien and Luther Chien. A modern day Silk Road — an ancient trading route that hooked up China with the Middle East — could forge scientific links between China, the United States and other Western nations.
In the meantime, China should not ignore its agricultural economy, says T. C. Tso. By 2050, the demand for food is set to double, while the amount of arable land will fall by a fifth. Using current technologies, it will be impossible to increase food production to the level that is needed. Scientists could work to produce plants with improved yields. New farmland could also be developed — but not at the expense of biodiversity. China is home to 10% of the world's biodiversity. Conservation is urgently needed, argue Chung-I Wu, Suhua Shi and Ya-ping Zhang, but to be taken seriously it needs a strong scientific basis and must attract the brightest scientists.
All the articles in this supplement will be available on the Nature press site
[8] Reproduction: Ovarian transplant yields baby monkey (pp137-138)
Fertility researchers have successfully produced a baby rhesus monkey after transplanting part of its mother's ovary to a different site in her body. The process represents a step towards transplanting functional ovarian tissue in cancer patients who may have been sterilized by radiation and chemotherapy.
The monkey is the first primate to be born after an ovarian transplant, report D. M. Lee and colleagues in a Brief Communication in this week's Nature. The researchers removed ovarian tissue from each of seven monkeys and transferred it to the abdomen, arm or next to the kidney, each monkey receiving a transplant of her own ovarian tissue. They then extracted developed eggs from the tissue and transferred them after fertilization into the wombs of surrogate mothers, one of which became pregnant and gave birth to a healthy baby.
The technique sets the stage for similar procedures in humans, although those undergoing chemotherapy will require the transplanted tissue to be frozen until needed, rather than used fresh, as in this case. "This procedure could potentially rescue fertility in cancer survivors," the authors say.
[9] And Finally"¦: Grandmas give kids a start in life (pp178-181; N&V)
Most animals reproduce until they die, but in humans the majority of women live long after menopause. Research published in this week's Nature may shed some light on this rare occurrence within the animal kingdom.
Using multi-generational data from Finland and Canada, Mirkka Lahdenperä and colleagues discovered that women with a longer post-reproductive lifespan have more grandchildren and so pass more of their genes on to future generations. Simply put, they help their children to breed earlier, more successfully and more frequently.
The results support the 'Grandmother hypothesis' — that women of a certain age are better off helping their children to raise offspring than having any more kids of their own. Consistent with this, the authors found that grandmothers become more likely to die at around the time when their own offspring reach menopause. This is discussed further in an accompanying News and Views article by Kristen Hawkes.
ALSO IN THIS ISSUE"¦
[10] Supramolecular dendritic liquid quasicrystals (pp157-160)
[11] Links between salinity variation in the Caribbean and North Atlantic thermohaline circulation (pp160-163)
[12] Seismic reflection imaging of two megathrust shear zones in the northern Cascadia subduction zone (pp163-167)
[13] Unified spatial scaling of species and their trophic interactions (pp167-171)
[14] Myocardin and ternary complex factors compete for SRF to control smooth muscle gene expression (pp185-189)
[15] Control of the SCFSkp2"Cks1 ubiquitin ligase by the APC/CCdh1 ubiquitin ligase (pp190-193)
[16] Degradation of the SCF component Skp2 in cell-cycle phase G1 by the anaphase-promoting complex (pp194-198)
[17] Insight into tubulin regulation from a complex with colchicines and a stathmin-like domain (pp198-202)
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.
BRAZILManaus: 1Sao Paulo: 1
CANADABurnaby: 12Quebec: 9
FRANCEGif-sur-Yvette: 17Frenoble: 17Paris: 17
FINLANDTurku: 9
GERMANYTubingen: 14
PANAMABalboa: 1
UNITED KINGDOMBristol: 10Cambridge: 9Oxford: 3Sheffield: 9, 10
UNITED STATES OF AMERICA
California Berkeley: 13 Davis: 11 San Francisco: 13 Santa Barbara: 11Colorado Gothic: 13Connecticut New Haven: 4Maryland Bethesda: 6 Frederick: 6 Rockville: 6Massachusetts Boston: 2, 4, 16 Cambridge: 7Michigan Ann Arbor: 5New York New York: 15North Carolina Chapel Hill: 14Oregon Portland: 8Pennsylvania Philadelphia: 6, 10Texas Dallas: 14
Nature Publishing Group is a division of Macmillan Publishers Ltd.
Macmillan is an international publisher serving the information and education community as well as publishing fiction and non-fiction.
PLEASE CITE NATURE AND OUR WEBSITE www.nature.com/nature AS THE SOURCE OF THE FOLLOWING ITEMS. IF PUBLISHING ONLINE, PLEASE CARRY A HYPERLINK TO http://www.nature.com/nature
RSS