This press release is copyright Nature.
VOL.451 NO.7179 DATED 07 FEBRUARY 2008
This press release contains:
· Summaries of newsworthy papers:
Public Health: Tracking measles in sub-Saharan Africa
Stem cells: Circadian rhythms
Planetary science: Evidence for water
Plants: Recovery from nitrogen
Neurodegeneration: The plaque to dementia
DNA vaccines: TBK1 is doubly important
Essay: Darwin’s Enduring Legacy
Tectonics: Slice of subduction
And finally… Holography: An added dimension
· Mention of papers to be published at the same time with the same embargo
· Geographical listing of authors
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 Public Health: Tracking measles in sub-Saharan Africa (pp 679-684)
Vaccination has almost eliminated measles in many parts of the world, but it is still a major killer of infants in sub-Saharan Africa. A paper in this week’s Nature analyses the dynamics of measles epidemics in Niger and reveals how they might affect the success of prospective vaccination programmes.
Matthew Ferrari and colleagues show that the frequency of measles epidemics in Niger, particularly in the capital Niamey, is highly variable (‘episodic’). This result was unexpected, because in cities in industrialized countries with similarly high birth rates, regular epidemics occur annually. However, measles epidemics in Niamey often decline at the onset of the rainy season, regardless of the size of the outbreak, leading to inter-epidemic periods of unpredictable length and frequency, during which more children are born to fuel larger outbreaks.
The authors point out that offsetting the potentially devastating effects of these erratic boom-and-bust outbreaks will require efficient surveillance to detect them in the first place, as well as the correct balance between routine and reactive control strategies to hold them in check. Even then, eliminating the largest outbreaks will be difficult until vaccination coverage is complete.
Matthew Ferrari (The Pennsylvania State University, University Park, PA, USA)
Tel: +1 814 321 3347; E-mail: [email protected]
 Stem cells: Circadian rhythms (AOP)
***This paper will be published electronically on Nature's website on 06 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 07 February, but at a later date. ***
The release of blood stem cells into the bloodstream is regulated by circadian rhythms, according to research in this week’s Nature. The work suggests that release of haematopoietic stem cells (HSCs) during an animal’s resting period could promote the regeneration of blood stem cell populations and potentially other tissues.
HSCs circulate through the bloodstream and can home into sites throughout the body. Paul Frenette and colleagues show that these cells undergo marked fluctuations depending on circadian oscillations in mice induced by continuous light or jet lag. Expression of the chemokine CXCL12 in the stem cell niche corresponds to the circadian oscillations; this is a result of adrenergic signals locally delivered by nerves in the bone marrow.
The research demonstrates that the central nervous system can directly regulate the function of a stem cell niche in peripheral tissues. The team also believes that this knowledge could help to increase the yield of HSCs if stem cells are harvested at the right time.
Paul Frenette (Mount Sinai School of Medicine, New York, NY, USA)
Tel: +1 212 659 9693; E-mail: [email protected]
 Planetary science: Evidence for water (pp 685-688)
Scientists have modelled the dust-and-water plume swirling around the south pole of Enceladus, the sixth-largest moon of Saturn. The research, published in Nature this week, shows why the dust slows down as it escapes with the faster-moving water vapour.
Enceladus orbits in Saturn’s outermost ‘E’ ring and is one of only three outer Solar System bodies where active eruptions have been observed — tiny grains and water vapour are ejected in geyser-like volcanic eruptions. Previous studies have suggested that the dusty material released might be the source of Saturn’s E-ring, but both the dynamics and origin of the plume have remained a mystery.
Jürgen Schmidt and colleagues develop a theory that explains how these particles are created and shot into space, showing that the frequent collisions of grains against channel walls cause effective friction. They then derive particle speed and size distributions that reproduce the observed properties of the dust plume. The results also imply that liquid water exists in equilibrium with ice and vapour under the moon’s icy crust.
Jürgen Schmidt (University of Potsdam, Germany)
Tel: +49 331 977 1626; E-mail: [email protected]
 Plants: Recovery from nitrogen (pp 712-715)
Low-level increases of atmospheric nitrogen deposition, caused by human activity, may lead to a gradual loss of plant species diversity, suggests a paper in this week’s Nature. The same research shows that diversity recovered a decade after the cessation of experimental nitrogen addition, suggesting that some of the harmful effects of past damage can be reversed.
The use of nitrogen fertilizers and fossil fuel burning is causing nitrogen deposition in industrialized countries at up to seven times the pre-industrial rate. Christopher Clark and David Tilman used data from a 23-year study of prairie grasslands in Minnesota. Their work suggests that the long-term effects of such extended nitrogen deposition have been underestimated. Chronic low-level nitrogen addition led to a gradual loss of plant species diversity, but diversity had recovered 13 years after nitrogen addition had ceased, suggesting that some of the harmful effects of past deposition are reversed by reductions in the rate of deposition.
Christopher Clark (University of Minnesota, St. Paul, MN, USA)
Tel: +1 612 308 2737; E-mail: [email protected]
 Neurodegeneration: The plaque to dementia (pp 720-724; N&V)
Recent questions as to the role of amyloid plaques in the brains of patients with Alzheimer’s disease are addressed in Nature this week. The widely accepted hypothesis is that neural abnormalities in patients are the result of the gradual accumulation of amyloid plaques in the brain over decades, but some researchers believe that the defects come first and the plaque formation later.
Bradley Hyman and colleagues use imaging to follow plaque formation in a mouse model of Alzheimer’s disease and find that they form very quickly, within 24 hours. A day or two later the microglia move in and neuritic changes are seen. The data suggest that neuritic dysfunction follows, rather than precedes, amyloid deposition.
Bradley Hyman (Harvard Medical School, Charlestown, MA, USA)
Tel: +1 617 726 2299; E-mail: [email protected]
Eliezer Masliah (University of California, San Diego, CA, USA) N&V Author
Tel: +1 619 517 2226; E-mail: [email protected]
 DNA vaccines: TBK1 is doubly important (pp 725-729)
To develop optimal vaccines for clinical applications it is vital to understand the mechanisms of their actions, and research in Nature this week demonstrates how DNA vaccines may induce adaptive immune responses.
DNA vaccines induce adaptive immune responses, mainly through induction of type I interferons. Ken Ishii and colleagues use mice to show that this occurs by a mechanism that is independent of the activation of nucleic-acid-binding Toll-like receptors. Instead, some T-cell responses require activation of the TANK-binding kinase 1 (TBK1)-mediated innate immune signalling pathway in haematopoietic cells. In non-haematopoietic cells, TBK1 is critical for the activation of CD8 T cells. Therefore, in two distinct cellular mechanisms, TBK1 is a key player in DNA-vaccine-induced immunity.
Ken Ishii (Osaka University, Japan)
Tel: +81 6 6879 8301; E-mail: [email protected]
Essay: Darwin’s Enduring Legacy
As we gear up for marking the 200th anniversary of Darwin’s birth (12 February 1809) and the 150th of the publication of On the Origin of Species (1859), Kevin Padian reflects on what constitutes Darwin’s enduring greatness in Western thought. In an Essay in this week’s Nature, Padian writes: “His contributions can scarcely be reduced to a simple list, but the following ten topics hint at the magnitude of the man’s legacy.”
Padian numbers the following among Darwin’s most original and stimulating insights: natural selection, the tree of life, genealogical classification, selective extinction, deep time, biogeographical distributions, sexual selection, coevolution, the economy of nature, and gradual change. “Darwin moved intellectual thought from a paradigm of untestable wonder at special creation to an ability to examine the workings of that natural world, however ultimately created, in terms of natural mechanisms and historical patterns,” he says.
Kevin Padian (University of California, Berkeley, and President of the National Center for Science Education, Oakland, CA, USA)
Tel: +1 510 642 7434; E-mail: [email protected]
 Tectonics: Slice of subduction (pp 699-703)
Geologists have uncovered the first field evidence for an erosive subduction channel, preserved in the Northern Apennines of Italy. The ancient subduction zone provides clues to the processes that generate earthquakes at such active plate boundaries today. Modern geophysical imaging has been used to reveal the structure of active subduction zones around the world, but details of the subduction interface at depth are difficult to resolve as the boundaries are located deep in ocean trenches. Also, the overriding plate is often eroded away or dragged down into the subduction zone, destroying the geological record.
In this week’s Nature, Paola Vannucchi and co-authors describe a fossil erosive subduction channel that formed between the European and Adriatic plates during a transition period from oceanic subduction to continental collision. The channel is about 500 metres thick and represents the upper 5 kilometres of the subduction interface. They infer from their observations that the onset of seismic activity along the boundary occurred at lower temperatures than expected. The authors were also surprised to find two tectonic surfaces, indicating that erosion was occurring simultaneously at the top and base of a subduction channel. Veins discovered at about 3 kilometres depth point to the presence of fluids and alternation between zones of fast and slow slip along the boundary. This ancient subduction zone may therefore help to build a better picture of processes occurring at plate boundaries today, especially in the wake of recent drilling projects to reach the depth where such subduction-zone earthquakes are generated.
Paola Vannucchi (University of Florence, Italy)
Tel: +39 055 275 7494; E-mail: [email protected]
 And finally… Holography: An added dimension (pp 694-698; N&V)
Impressive new technology that allows an updateable 3D holographic display is presented in Nature this week. The research raises hopes for applications requiring situational awareness, such as medical, industrial and military imaging.
Three-dimensional holographic displays simulate natural human vision without the need for special eyewear, making them particularly suited to training in certain settings. Nasser Peyghambarian and colleagues report a new recording medium based on specially designed photo-responsive polymers and demonstrate a holographic 3D display based on this material that can record new images in a few minutes, has a significant size (4×4 inches), can be viewed for several hours without the need for refreshing, and can be readily erased and updated with new images. The new technique compares favourably with current commercial displays that tend to have poor image persistence or cannot update.
Nasser Peyghambarian (The University of Arizona, Tucson, AZ, USA)
Tel: +1 520 621 4649; E-mail: [email protected]
Joseph Perry (Georgia Institute of Technology, Atlanta, GA, USA) N&V Author
Tel: +1 404 385 6046; E-mail: [email protected]
ALSO IN THIS ISSUE…
 Towards a molecular understanding of shape selectivity (pp 671-678)
 Phase diagram of a two-component Fermi gas with resonant interactions (pp 689-693)
 Palaeotemperature trend for Precambrian life inferred from resurrected proteins (pp 704-707; N&V)
ADVANCE ONLINE PUBLICATION
***This paper will be published electronically on Nature's website on 06 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 07 February, but at a later date.***
 Formation and branch migration of Holliday junctions mediated by eukaryotic recombinases
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.
Kanagawa: 6, 12
UNITED STATES OF AMERICA
Menlo Park: 11
St Paul: 4
St Louis: 5
New York: 2
University Park: 1
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
Mika Nakano, Nature Tokyo
Tel: +81 3 3267 8751; E-mail: [email protected]
For the UK/Europe/other countries not listed above
Rachel Twinn, Nature London
Tel: +44 20 7843 4658; E-mail [email protected]
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