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Article Released Wed-25th-April-2007 18:22 GMT
Contact: Ruth Institution: Nature Publishing Group
 Neuronal imbalance may contribute to addiction

Summaries of newsworthy papers include Ocean science: A natural approach, Reducing the risk of severe adverse drug reactions, Swift study into wing shape, Weighing at the nanoscale, Invasive species thrive on hard times and finally… The perfect pint?

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This press release is copyright Nature. VOL.446 NO.7139 DATED 26 APRIL 2007


This press release contains:

· Summaries of newsworthy papers:

Neuroscience: Neuronal imbalance may contribute to addiction

Ocean science: A natural approach

Commentary: Reducing the risk of severe adverse drug reactions

Flight: Swift study into wing shape

Nanotechnology: Weighing at the nanoscale

Conservation: Invasive species thrive on hard times

And finally… The perfect pint?

· Mention of papers to be published at the same time with the same embargo

· Geographical listing of authors



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[1] Neuroscience: Neuronal imbalance may contribute to addiction (pp 1086-1090)



An imbalance between neuronal excitation and inhibition may contribute to the early stages of addiction, a paper published this week in Nature suggests. The finding may prove useful therapeutically.

Excitatory synapses — nerve cell connections that push target neurons to fire more readily — are known to become stronger upon use, a process that is involved in learning and memory. Julie A. Kauer and colleagues show that this excitatory 'long-term potentiation' (LTP) goes hand in hand with LTP at neighbouring inhibitory synapses in a culture system.

The inhibitory synapses, which use the neurotransmitter GABA, signal to dopaminergic neurons in the ventral tegmental area of the rat brain, an area known to be involved in drug addiction. Treating the cells with morphine blocks this GABA-dependent LTP.

The resulting imbalance between excitatory and inhibitory cells may enhance the firing of dopamine neurons and so fuel the addictive process. Drugs that target the relevant GABA receptors may interfere with this process.

CONTACT

Julie A. Kauer (Brown University, Providence, RI, USA)

Tel: +1 401 863 9803; E-mail: Julie_Kauer@Brown.edu





[2] Ocean science: A natural approach (pp 1070-1074; N&V)



Changes in the supply of iron from deep water to the surface ocean may have a greater effect on atmospheric carbon dioxide concentrations than previously thought, a Nature paper suggests. The finding may have implications for interpretations of past climate change as well as future climate prediction.

Iron plays an important role in the carbon cycle because its availability as a micronutrient limits primary productivity over large areas of the ocean — phytoplankton need iron to fix energy into carbon, which is then sequestered in the deep ocean when the microorganisms die and sink out of the surface layer. Yet the exact effect of changes in iron supply on the amount of carbon sequestered remains unclear.

Stéphane Blain and colleagues studied a particular phytoplankton bloom that occurs in the Southern Ocean when large quantities of iron and nutrients well up from deep waters below. They found that the efficiency of fertilization — the ratio of carbon exported to the ocean interior to the amount of iron supplied — is at least ten times higher than previous estimates from short-term experiments involving artificial addition of iron to the ocean. This difference occurs because the iron is supplied slowly and continuously, and because the bloom is also dependent on the supply of major nutrients from below, indicating that such high efficiencies are unlikely to be achieved through artificial 'fertilization' of the ocean with iron.

CONTACT

Stéphane Blain (Universite de la Mediterranee, CNRS, Marseille, France)
Tel: +33 298 829 369; E-mail: stephane.blain@univmed.fr



Philip W. Boyd (University of Otago, Dunedin, New Zealand) N&V author

Tel: +64 3 479 5249; E-mail: pboyd@alkali.otago.ac.nz





Commentary: Reducing the risk of severe adverse drug reactions



A global research network is needed to reduce the incidence of serious adverse drug reactions (SADRs), according to a Commentary in this week’s Nature. Kathleen M. Giacomini and her colleagues argue that, along with the promise of emerging genomic technologies, the establishment of a global SADR pharmacogenomics network will help to identify those populations that are genetically at risk.

Although SADRs are relatively rare once a drug is marketed, they are estimated to be the fourth leading cause of death in the United States, and it is thought that each year around 2 million patients will experience an SADR when using marketed drugs. Similar numbers have been estimated for other Western countries. However, precisely what constitutes an SADR is not always easily defined, and many of the genetic risk factors remain unknown. Important goals proposed by the authors include generating predictive tests and improving our understanding of the molecular mechanisms that underlie SADRs, so that safer drugs can be developed.

The authors suggest that developing a global network will help to overcome the most challenging issue in identifying genetic risk factors for SADRs — that the number of cases a single site or even country can generate is often too small for adequate genetic analysis. A global network would also have the advantage of involving multiple ethnic groups.

Significant steps have already been taken in that regional and multicentre SADR networks exist in Canada and Europe, and moves are being made in that direction in the United States. With these in place, the authors recommend that efforts should now be made to secure sufficient resources — from national and international funding agencies along with other stakeholders — to establish and support a global SADR pharmacogenomics network.

In a related news feature in this week’s Nature, Erika Check discusses previous setbacks and the emergence of safer drugs in the field of antibody therapy.

CONTACT

Kathleen M. Giacomini (University of California, San Francisco, CA, USA)
Tel: +1 415 476 1936; E-mail: kmg@itsa.ucsf.edu



Erika Check (Journalist, Nature)

Tel: +1 415 403 9025; E-mail: echeck@nature.com





[3] Flight: Swift study into wing shape (pp 1082-1085)



Swifts can dramatically enhance their flight performance by altering their wing shape, a paper in this week’s Nature reveals. Studies of such ‘morphing’ may help shape the future design of aircraft wings.

Common swifts (Apus apus) spend most of their lives on the wing, foraging, courting, migrating and even roosting. Gliding swifts frequently change wing shape, supposedly to improve performance. By studying the aerodynamic and structural performance of swift wings in a wind tunnel, David Lentink and colleagues have now confirmed that this happens. Choosing the most suitable sweep angle can halve sink speed or triple turning rate. Extended wings are superior for slow glides and turns. Swept wings, in contrast, are superior for fast glides and turns and although less effective at generating lift, they can bear the extreme accelerational loads of fast manoeuvres in the air.

The results help explain swifts’ behaviour choices — swifts roost at the most energy-efficient glide speed — and the insights gained could offer efficiency and agility to next-generation surveillance aircraft.

CONTACT

David Lentink (Wageningen University, The Netherlands)
Tel: +31 31748 3965; E-mail: david.lentink@wur.nl





[4] Nanotechnology: Weighing at the nanoscale (pp 1066-1069)



Single nanoparticles have been weighed in fluid with a microresonator mass detection system that, for the first time, achieves sub-femtogram (less than one thousandth of a millionth of a millionth, or 10−15, of a gram) resolution.

Detecting frequency changes when a sample is vibrated on a resonator provides a measurement of mass. To be accurate at the very smallest scale, this weighing by mechanical resonance is conducted in vacuum, but for applications involving biological or environmental samples, measurements typically need to be done in a fluid. Unfortunately, the viscosity of liquids can seriously degrade the sensitivity of this technique.

Scott R. Manalis and colleagues present their findings in Nature this week. They overcame this hurdle remarkably simply, by putting the fluid sample inside the resonator. They have developed a new microfluidic device and used it to accurately weigh nanoparticles and single bacterial cells.

The authors suggest that their new technique could be useful in applications of flow-through mass sensing, such as diagnostics.

CONTACT

Scott R. Manalis (Massachusetts Institute of Technology, Cambridge, MA, USA)
Tel: +1 617 253 5039; E-mail: scottm@media.mit.edu





[5] Conservation: Invasive species thrive on hard times (pp 1079-1081; N&V)



Native species might be expected to outperform invasive species when resources are low because they have had more time to adapt to the conditions. But this is not always the case, according to a Nature paper to be published this week that has important implications for habitat management and conservation.

Jennifer L. Funk and Peter M. Vitousek looked at the resource-use efficiency of invasive and native species in three habitats in Hawaii where light, water or nutrient availability was limiting to plant growth. Invasive plant species that had successfully colonized resource-poor habitats were more efficient at using limiting resources than native species, they found.

The findings have repercussions for native ecosystem restoration strategies and call into question any management strategy that relies on lowering resource availability to favour the growth of native species.

CONTACT

Jennifer L. Funk (Stanford University, CA, USA)
Tel: +1 650 815 5525; E-mail: funk@stanford.edu



Tim Seastedt (University of Colorado, Boulder, CO, USA) N&V author

Tel: +1 303 492 3302; E-mail: timothy.seastedt@colorado.edu





[6] And finally… The perfect pint? (pp 1053-1055; N&V)



Researchers have devised an equation that could be used to predict how the head on a pint of beer changes over time. The formula, which solves a long-standing mathematical puzzle, can help predict how granular structures coarsen and may find use in various industrial and commercial settings.

Cellular structures, such as foams and crystalline grains in metals and ceramics, are ubiquitous in nature, and their walls can sometimes move under the influence of their surface tension. As a result, the cells evolve and the structure coarsens — just as the froth on a glass of beer evolves and changes over time. Over 50 years ago, polymath John von Neumann derived a formula for the growth rate of a cell in a two-dimensional structure. In this week’s Nature, Robert D. MacPherson and David J. Srolovitz do the same thing for a cell in three or more dimensions.

Cellular structures also occur in biological tissue and magnetic materials. So the results may speed the development of models that can predict the evolution of surface-tension-driven microstructures in a wide array of settings — such as the heat treatment of metals, or even controlling the head on a pint of beer.

CONTACT
Robert D. MacPherson (Institute for Advance Study, Princeton, NJ, USA)

Tel: +1 609 734 8133; E-mail: rdm@math.ias.edu



David J. Srolovitz (Yeshiva University, New York, NY, USA)
Tel: +1 212 960 5214; E-mail: srol@yu.edu



David Kinderlehrer (Carnegie Mellon University, Pittsburgh, PA, USA) N&V author

Tel: +1 412 268 5729; E-mail: davidk@andrew.cmu.edu




ALSO IN THIS ISSUE…



[7] Chlorine isotope homogeneity of the mantle, crust and carbonaceous chondrites (pp 1062-1069)



[8] The role of fluids in lower-crustal earthquakes near continental rifts (pp 1075-1078)



[9] Expanding the diversity of chemical protein modification allows post-translational mimicry (pp 1105-1109; N&V)




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

Hobart: 2, 7

BELGIUM

Brussels: 2

FRANCE

Arcachon: 2

Banyuls-sur-Mer: 2

Gif-sur-Yvette: 2

Marseille: 2

Paris: 2

Plouzane: 2

Toulouse: 2

Vandoeuvre-Les-Nancy: 7

Villefranche-sur-Mer: 2

Wimereux: 2


NETHERLANDS

Delft: 3

Haren: 3

Leiden: 3

Lund: 3

Texel: 2

Wageningen: 3



NEW ZEALAND

Lower Hutt: 8



UNITED KINGDOM

Leeds: 8

Oxford: 9



UNITED STATES OF AMERICA

California

Davis: 8

Santa Barbara: 4

Stanford: 5

Illinois

Galesburg: 1

Massachusetts

Cambridge: 4

New Jersey

Princeton: 6

New Mexico

Albuquerque: 7

New York

New York: 6

Rhode Island

Providence: 1





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For North America and Canada

Katie McGoldrick, Nature Washington

Tel: +1 202 737 2355; E-mail: k.mcgoldrick@naturedc.com



For Japan, Korea, China, Singapore and Taiwan

Mika Nakano, Nature Tokyo

Tel: +81 3 3267 8751; E-mail: m.nakano@natureasia.com



For the UK/Europe/other countries not listed above

Helen Jamison, Nature London

Tel: +44 20 7843 4658; E-mail h.jamison@nature.com





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Keywords associated to this article: Neuroscience, Ocean science, drug reactions, wing shape, Nanotechnology, Conservation, perfect pint
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