This press release contains:
· Summaries of newsworthy papers:
Earthquakes: Slip on the Peru megathrust
Opinion: Financial squeeze could focus universities
Immunology: Elite model for HIV
Opinion: The ozone hole 25 years on
Geophysics: Magnetic field within the Earth's core
Molecular biology: The cause of sprouting
Physics: An ultralow-noise amplifier for quantum applications
And finally… Bend me, shape me
· Mention of papers to be published at the same time with the
same embargo
· Geographical listing of authors
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[1] Earthquakes: Slip on the Peru megathrust (pp 78-81)
Most fault movement along the coast of central Peru is actually gradual creep that occurs between major earthquakes, suggests a paper in Nature this week. The study sheds new light on megathrust faults along subduction zones and their influence on the seismic cycle, indicating that the return period of a magnitude 8.0 earthquake in the Pisco area is estimated to be 250 years.
Active faults are made up of areas that slip mostly during earthquakes, and areas that slip ‘aseismically’ as a steady creep between earthquakes. The size, location and frequency of earthquakes generated on megathrust faults depend on where and when aseismic creep is taking place, and what fraction of the long-term slip rate it accounts for.
Hugo Perfettini and colleagues show that the 2007 magnitude 8.0 Pisco earthquake in central Peru ruptured two areas within a patch that had remained locked since the last big quake, and triggered a seismic frictional afterslip on two adjacent patches. The study shows that about half the slip budget is actually aseismic to depths of 40 kilometres. The subducting Nazca ridge coincides with a prominent patch that creeps aseismically, and seems to have acted as a barrier to the propagation of large earthquakes in the past.
Author contact
Hugo Perfettini (Institut de Recherche pour le Développement, Lima, Peru)
Tel: +51 1 441 32 23
E-mail: [email protected]
Opinion: Financial squeeze could focus universities (pp 32-33)
The tightening of the US science budget means that some universities are likely to lose their research programmes. But this could actually lead to an improvement in teaching and research, says Diane Auer Jones in an Opinion piece in Nature this week.
A boom in federal science funds over the past decade has been matched by a rise in the number of universities doing research. Colleges that formerly focused on undergraduate teaching set up research programmes to get access to this new source of money and boost their rankings. But this was misguided, says Jones. It has spread research dollars too thinly, forcing some faculty members to take on more duties than they can manage. Some teachers now don’t have the time and energy to focus on classes, and so students — particularly younger students — lose out. More money isn’t always a good thing.
A restriction in cash will force institutions to focus on what they do best: research or teaching. Many universities should offer faculty members the option of teaching-only positions, and invest in shared lab space with other institutions. The result would be cheaper tuition, happier faculty members, a more efficient research enterprise and a better environment for students.
Author contact
Diane Auer Jones (The Washington Campus, DC, USA)
Tel: +1 202 234 4446 or: +1 202 218 0433
E-mail: [email protected]
[2] Immunology: Elite model for HIV (AOP)
DOI: 10.1038/nature08997
This paper will be published electronically on Nature's website on 05 May 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 06 May, but at a later date.
A new immunological model may explain why certain HIV-infected individuals maintain extremely low viral loads over long time periods without therapy. The study, revealed in this week’s Nature, has implications for vaccine design.
The model, proposed by Bruce Walker and colleagues, describes how these so-called ‘elite controllers’ might generate an effective immune response to HIV. It focuses on a particular protein complex, HLA-B57, that is enriched in elite controllers and helps present viral particles to the immune system for destruction by T cells. According to the model, HLA-B57 binds fewer self-peptides, resulting in a T cell repertoire with enhanced cross-reactivity and leading to a more effective T-cell response against the virus.
Author contact
Bruce Walker (Ragon Institute, Boston, MA, USA)
Tel: +1 617 724 7524
E-mail: [email protected]
Opinion: The ozone hole 25 years on (pp 34-35)
In 1985, Joseph Farman, Brian Gardiner and Jonathan Shanklin reported in Nature their discovery of the ozone hole over Antarctica — a dramatic thinning of ozone in the spring, linked to the accumulation of chlorofluorocarbons (CFCs) in the atmosphere.
In an Opinion piece in this week’s Nature marking the twenty-fifth anniversary of this work, Shanklin remembers how luck played a big part in the original discovery. The ozone monitor at the Halley Research Station in Antarctica had been set up for weather forecasting, not long-term environmental monitoring, and the British Antarctic Survey had considered discontinuing it in the face of budget cuts. Shanklin himself had no training in atmospheric chemistry, but this gave him an open mind when looking at the data — which no one expected to show sudden springtime declines. His curiosity was piqued when making a graph that was intended to reassure the public that ozone levels had not gone down.
The dramatic find helped to seal the deal on the Montreal Protocol to phase out CFCs. As a result of the success of this agreement, the Antarctic ozone levels are expected to return to their 1950s levels by 2080. A global deal on climate change, however, seems destined to be more difficult, says Shanklin, because of economic and social stumbling blocks. But the ozone hole showed just how quickly the planet can change. “Given the speed with which mankind can affect it,” he says, “following the precautionary principle is likely to be the safest road to future prosperity.”
Author contact
Jonathan Shanklin (British Antarctic Survey, Cambridge, UK)
E-mail: [email protected]
Media contact
Linda Capper (British Antarctic Survey)
Tel: +44 1223 221448
E-mail: [email protected]
[3] Geophysics: Magnetic field within the Earth's core (pp 74-77; N&V)
Scientists have calculated the magnetic field strength inside the Earth’s core, solving a long-standing puzzle in Earth science, according to a paper in Nature this week.
The Earth’s solid inner core is surrounded by a fluid outer layer that is composed mainly of iron and which, as it convects, generates the Earth’s magnetic field. The magnetic field within the Earth’s core itself cannot be probed directly, so scientists have used indirect methods to estimate its strength, but these methods have not yielded consistent results. Observations of the Earth’s length of day with oscillations at a period of sixty years have been used to estimate an internal field of only ~0.2 milliTesla, whereas numerical models have predicted that the magnitude of the field inside the core should be an order of magnitude larger, at 3 milliTesla.
Nicolas Gillet and colleagues now resolve this discrepancy. Using models of fluid flow in the core, they find a torsional (twisting) wave recurring every six years, and from this they estimate a field strength of 4 millitesla inside the Earth’s core. This new model reconciles previous theoretical approaches from studies of geomagnetic and geodetic data, and numerical simulations of the geodynamo.
Author contact
Nicolas Gillet (Université Joseph Fourier, Grenoble, France)
Tel: +33 4 76 63 51 78
E-mail: [email protected]
N&V author
Andy Jackson (ETH Zurich, Switzerland)
Tel: +41 44 633 73 49
E-mail: [email protected]=
[4] & [5] Molecular biology: The cause of sprouting (AOP)
DOI: 10.1038/nature09002
DOI: 10.1038/nature08995
These papers will be published electronically on Nature's website on 05 May 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 them on this release to avoid multiple mailings they will not appear in print on 06 May, but at a later date.
The sprouting of new blood and lymph vessels from pre-existing ones is controlled by the membrane protein ephrin-B2, reveal two studies in this week's Nature. The finding has important implications for the treatment of tumours.
Both the normal developmental sprouting of blood and lymph vessels, and the pathological sprouting that occurs in tumours, requires the formation and guidance of specialized endothelial tip cells.
Ralf Adams and colleagues have either knocked out or overexpressed genes in mice to show that ephrin-B2 underpins the transformation of quiescent endothelial cells in blood and lymphatic vessels into motile, invasive ones. For both types of vessel, growth is reduced in loss-of-function mutants whereas overexpression of ephrin-B2 promotes sprouting.
This finding is supported by the results of a study by Amparo Acker-Palmer and colleagues. They show that mice with deficient ephrin-B2 PDZ signalling have fewer endothelial tip cells and those cells have fewer cytoplasmic projections, whereas overexpression of ephrin-B2 increases vessel branching. Acker-Palmer and his group also show that the growth of a mouse tumour can be decreased by blocking the ephrin-B2 PDZ signalling pathway.
Ephrin-B2 seems to exert its effect by regulating the cellular uptake of members of the vascular endothelial growth factor (VEGF) family of receptors.
Author contact
Ralf Adams (Max Planck Institute for Molecular Biomedicine, Münster, Germany) – Author paper [4]
Tel: +49 70365 410
E-mail: [email protected]
Amparo Acker-Palmer (Goethe University Frankfurt, Germany) – Author paper [5]
Tel: +49 69 798 29645
E-mail: [email protected]
[6] Physics: An ultralow-noise amplifier for quantum applications (pp 64-68)
A new kind of microwave signal amplifier is demonstrated in this week’s Nature. With a total noise level of only three times the fundamental limit imposed by quantum mechanics, the system should find application in quantum information processing, and more generally in the measurement of very weak signals.
Sensitive physical measurements require the use of amplifiers. These inevitably add noise to the signal, thereby degrading the information that it carries. Recent progress in quantum information processing, using microwave signals to read and manipulate solid-state quantum bits (qubits), has stimulated the search for ultralow-noise amplifiers operating at microwave frequencies.
Nicolas Bergeal and colleagues now demonstrate the operation of such an amplifier, based on a superconducting device called a Josephson ring modulator. The new amplifier is ‘phase-preserving’; that is, it preserves information encoded in both the phase and the amplitude of the incoming signal. The added noise is only three times the fundamental quantum limit, which makes the amplifier 20–40 times better than the best commercial transistor amplifiers. The system’s high gain and very low noise will make it useful for applications such as the readout of solid-state qubits, single photon detection, and the production of entangled pairs of microwave photons, for use in quantum cryptography.
Author contact
Nicolas Bergeal (ESPCI ParisTech, France)
Tel: +33 1 40 79 44 83
E-mail: [email protected]
[7] And finally… Bend me, shape me (pp 69-73; N&V)
Artificial proteins crosslinked into a solid biomaterial mimic the elastic properties of muscle, says a report in Nature this week. The biomaterial created might be used in the future as a scaffold for engineering muscle tissue, although further testing is needed to assess its biocompatibility.
Hongbin Li and colleagues engineered artificial proteins that mimic the molecular structure of titin — the muscle protein that largely governs the elastic properties of muscle. They tested the nanomechanical properties of the new proteins at a single-molecule level and then crosslinked them into a solid rubber-like material. The resulting biomaterial showed high resilience at low strain and was extensible and tough at high strain — features that make up the passive elastic properties of muscles. The authors suggest that the properties of these materials could be fine-tuned to resemble specific types of muscle by adjusting the compositions of the proteins.
This work represents a step forward in the design at the single-molecule level of potentially useful biomaterials.
Author contact
Hongbin Li (University of British Columbia, Vancouver, Canada)
Tel: +1 604 822 9669
E-mail: [email protected]
N&V author
Elliot Chaikof (Emory University, Atlanta, GA, USA)
Tel: +1 404 727 8413
E-mail: [email protected]
ALSO IN THIS ISSUE…
[8] Deciphering the splicing code (pp 53-59; N&V)
[9] H_2 emission arises outside photodissociation regions in
ultraluminous infrared galaxies (pp 60-63)
ADVANCE ONLINE PUBLICATION
This paper will be published electronically on Nature's website on 05 May 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 06 May, but at a later date.
[10] Progesterone induces adult mammary stem cell expansion
DOI: 10.1038/nature09091
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.
AUSTRALIA
Westmead: 10
CANADA
Toronto: 8, 10
Vancouver: 7
FRANCE
Grenoble: 1, 3
Marseille: 1
Paris: 3, 6
Toulouse: 1, 4
Valbonne: 1
GERMANY
Frankfurt: 5
Giessen: 5
Münster: 4
PERU
Lima: 1
SWITZERLAND
Bern: 4
Schlieren: 4
UNITED KINGDOM
Bristol: 4
Cambridge: 8, 10
London: 4
UNITED STATES
California
Berkeley: 6
Livermore: 1
Pasadena: 1
San Francisco: 2
Santa Cruz: 1
Connecticut
New Haven: 6
Maryland
Chevy Chase: 2
Frederick: 2
Massachusetts
Boston: 2, 4
Cambridge: 2
New Jersey
Princeton: 9
Virginia
Blacksburg: 7
Wisconsi
Milwaukee: 5
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