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This press release is copyright Nature.
VOL.446 NO.7131 DATED 01 MARCH 2007
This press release contains:
* Summaries of newsworthy papers:
Infectious diseases: Minimalist mitochondria
Microscopy: Microscopes offer chemical ID
Immunology: Silkworm virus sussed
Developmental biology: Skin deep
Materials: How flat can flat get?
And finally… Organization in the zebrafish spinal cord
* Mention of papers to be published at the same time with the same embargo
* Geographical listing of authors
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[1] Infectious diseases: Minimalist mitochondria (pp 88-91)
The mitochondrial DNA of the human malaria parasite Plasmodium falciparum serves only one function, researchers report in this week's Nature. The minimalist genome is involved in mitochondrial electron transport, a target of certain important antimalarial drugs.
Akhil B. Vaidya studied the blood stages of the malaria parasite and discovered that the mitochondrial DNA is needed for making the electron acceptor ubiquinone. This in turn is needed by the parasite to make pyrimidine, the basic compound found in nucleic acids such as DNA and RNA.
The study helps underpin the mechanism by which anti-malarials such as proguanil work - they inhibit mitochondrial electron transport. It also offers insight into the ongoing evolution of mitochondrial genomes. It's thought that mitochondria emerged long ago when prokaryotes and eukaryotes forged a symbiotic relationship. But the arrangement has been in continuous flux, with varying degrees of gene loss and transfer occurring in the mitochondrial genomes of different eukaryotes.
CONTACT
Akhil B. Vaidya (Drexel University College of Medicine, Philadelphia, PA, USA)
E-mail: [email protected]
Please note the author will be travelling in India until 10 March, but will have access to e-mail and can be contacted on the following numbers:
Tel: +91 223 254 9363 or +91 982 061 6807
[2] Microscopy: Microscopes offer chemical ID (pp 64-67; N&V)
It’s now possible to use atomic force microscopy to work out the chemical make-up of individual surface atoms, a paper in this week’s Nature reveals.
Atomic force microscopy works by measuring the short-range forces that occur between a tiny tip and the atoms on the surface of a sample, allowing the structure of that surface to be imaged with atomic resolution. But the precise forces between the tip and the atoms also depend subtly on the identity of the atoms involved. Oscar Custance and colleagues have refined the imaging technique to the point where it is possible not only to detect individual atoms but also to recognise their chemical identity, even at room temperature.
The system can successfully distinguish between atoms of silicon, tin and lead, even though these three elements have similar chemical properties and identical preferences for particular surface positions. It’s hoped the method will boost research in areas such as materials science and semiconductor technology where important functional properties are controlled by the chemical nature and short-range ordering of individual atoms.
CONTACT
Oscar Custance (Osaka University, Japan)
Tel: +81 6 6879 7763; E-mail: [email protected]
Alexander Shluger (University College London, UK) N&V author
E-mail: [email protected]
[3] Immunology: Silkworm virus sussed (pp 97-101; N&V)
Researchers have cracked the structure of the microcrystals that shield and protect silkworm cypovirus particles. The structure helps explain the resilience of these insect viruses and may aid the development of insecticides and novel therapeutics.
Cypoviruses are hard to kill because hundreds of the infectious viral particles are embedded in tiny protein crystals called polyhedra. The polyhedra structure is striking in its resemblance to some viral outer shells or 'capsid' proteins, but is unique in other ways, say Peter Metcalf and colleagues in this week's Nature. And the resulting ultrastable, sealed crystals shield the virus particles from environmental damage.
The authors also discovered bound nucleotides within the crystals, raising the possibility that polyhedra-like nanoparticles could be used as storage and delivery devices for small molecules or drugs.
CONTACT
Peter Metcalf (The University of Auckland, New Zealand)
Tel: +64 9 373 7599 x84810; E-mail: [email protected]
Felix A. Rey (Institut Pasteur, Paris, France) N&V author
Tel: +33 1 45 68 85 63; E-mail: [email protected]
[4] Developmental biology: Skin deep (AOP)
DOI: 10.1038/nature05574
***This paper will be published electronically on Nature's website on 28 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 01 March, but at a later date.***
A single type of progenitor cell is responsible for maintaining the cells that make up the mouse epidermis, a paper published online in Nature this week suggests. The finding is surprising because if true, it overturns a well-established alternative theory, which holds that two different cell types are involved.
The outer layer of mammalian skin continually sloughs off and is replaced from within. One view is that long-lived, self-renewing stem cells give rise to short-lived, non-renewing progenitors, which in turn form the epidermis.
Philip H. Jones and colleagues now show that this is not the case, at least in mouse tail epidermis. Using genetic labelling and three-dimensional imaging techniques, they track the fate of single mouse epidermal progenitor cells over a one-year timescale. Their findings are consistent with the idea that a single type of progenitor cell gives rise to all the cells in this outer skin layer.
CONTACT
Philip H. Jones (Hutchison-MRC Research Centre, Cambridge, UK)
Tel: +44 1223 763 379; E-mail: [email protected]
[5] Materials: How flat can flat get? (pp 60-63)
There may be no such thing as a perfectly flat two dimensional sheet, according to research in this week’s Nature.
Jannik Meyer and colleagues cleaved individual sheets of carbon atoms, called graphenes, off small graphite blocks. They then placed them over a microscale scaffold and studied their structure. The team concluded that these free-standing atom-thick membranes are not flat, as might be expected, but wavy. The undulations appear to be less pronounced in a two-layer system, and disappear completely in a multilayer sample.
This ‘waviness’ may shed light on the reasons behind the structural stability of these extremely thin carbon membranes, which exhibit a range of other interesting properties.
CONTACT
Jannik Meyer (University of California, Berkeley, CA, USA)
Tel: +1 510 642 0190; E-mail: [email protected]
[6] And finally… Organization in the zebrafish spinal cord (pp 71-75)
State-of-the-art imaging techniques reveal an unexpected pattern of organization within the spinal cord of zebrafish. In a paper in this week’s Nature, Joseph R. Fetcho and colleagues describe their finding that neurons in the spinal cord of larval zebrafish (Danio rerio) are arranged in accordance with the swimming speed at which they are active.
The authors used electrophysiology and in vivo imaging to reveal a systematic relationship between spinal neuron location and swimming frequency. Motor neurons and excitatory interneurons located more dorsally - that is, towards the upper half of the spinal cord - were engaged at faster swimming speeds, whereas those located more ventrally - towards the lower half of the spinal cord - were active at slower speeds. By laser-ablating neurons at different levels of the spinal cord, the authors confirm that the pattern of organization that they observe has functional consequences. They report that the destruction of ventral, but not dorsal, excitatory interneurons disturbed slow movements.
Whether these findings might generalize to the more complex spinal cords of reptiles, birds and mammals is unclear, but they do shed light on how the spinal cord of zebrafish is organized to produce movements over a broad range of speeds.
CONTACT
Joseph R. Fetcho (Cornell University, Ithaca, NY, USA)
Tel: +1 607 254 4341; E-mail: [email protected]
ALSO IN THIS ISSUE…
[7] Transport and Anderson localization in disordered two-dimensional photonic lattices (pp 52-55; N&V)
[8] Bipolar supercurrent in graphene (pp 56-59)
[9] Implications for plastic flow in the deep mantle from modelling dislocations in MgSiO3 minerals (pp 68-70)
[10] Gating pore current in an inherited ion channelopathy (pp 76-78; 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.
CZECH REPUBLIC
Prague: 2
FRANCE
Villeneuve d’Ascq: 9
GERMANY
Konstanz: 3
Stuttgart: 5
ISRAEL
Haifa: 7
JAPAN
Aichi: 6
Kyoto: 3
Osaka: 2, 3
Saitama: 2
NETHERLANDS
Delft: 8
Nijmegen: 5
NEW ZEALAND
Auckland: 3
SPAIN
Madrid: 2
SWITZERLAND
Villigen: 3
UNITED KINGDOM
Cambridge: 4
Manchester: 5
UNITED STATES OF AMERICA
Illinois
Chicago: 6
New York
Ithaca: 6
Pennsylvania
Philadelphia: 1
Washington
Seattle: 10
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For the UK/Europe/other countries not listed above
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Tel: +44 20 7843 4658; E-mail [email protected]
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