This press release is copyright Nature.
VOL.445 NO.7129 DATED 15 FEBRUARY 2007
This press release contains:
* Summaries of newsworthy papers:
Immunology: HIV reveals vulnerable side
Astronomy: Forming the darkest galaxies in the Universe
Evolutionary psychology: Family ties
Particle acceleration: Wave up
Ecology: Conservation strategy rethink
* Mention of papers to be published at the same time with the same embargo
* Geographical listing of authors
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 Immunology: HIV reveals vulnerable side (pp 732-737)
Researchers have snuck a detailed peek at the crystal structure of a known broadly neutralizing human immunodeficiency virus (HIV-1) antibody as it binds to a specific part of HIV-1. The find, reported in this week’s Nature, is important because the binding site represents a chink in HIV’s armour that could help guide future vaccine development.
HIV keeps one step ahead of the human immune system by mutating frequently and changing its shape. But certain parts of the virus must remain relatively unchanged so that it can continue to bind to and enter human cells. gp120, a glycoprotein that juts out from the surface of the virus and binds to CD4 receptor on host cells, is one such region, making it a target for vaccine development.
Peter D. Kwong and colleagues made variants of stable gp120 that could be recognized by antibodies. They then looked in detail at the binding of one antibody, called b12, to the glycoprotein and found that the antibody approaches in an orientation very similar to that of CD4. Although other antibodies bind at this sight, b12 is the only one that binds and neutralizes a relatively broad range of HIV-1 isolates, so the results may help explain why.
Peter D. Kwong (National Institute of Allergy and Infectious Diseases, NIH, Bethesda, MD, USA)
Tel: +1 301 594 8685; E-mail: [email protected]
 Astronomy: Forming the darkest galaxies in the Universe (pp 738-740)
Researchers may have worked out how dwarf spheroidals - the most dark-matter-dominated galaxies known - were formed. Their results are published in this week's Nature.
Dwarf spheroidals orbit the Milky Way and Andromeda galaxies. But no proposed model of origin can simultaneously explain this and their exceptional dark-matter content. Using computer simulations, Lucio Mayer and colleagues suggest that dwarf spheroidals started life as gas-dominated dwarf galaxies. Then as these small galaxies passed through the larger Milky Way or Andromeda galaxy early in their lives, their gas was stripped away. What we see today is a tiny stellar component - the stars that had time to form before the gas was stripped away - embedded in a halo of dark matter that is large relative to the small numbers of stars.
Lucio Mayer (University of Zurich, Switzerland)
Please note the author is traveling and may have intermittent email access.
From 10-17 February they may be reached at: Tel: +1 800 452 4240; E-mail: [email protected]
It may also be easier to contact the following co-author:
Stelios Kazantzidis (Stanford University, CA, USA)
 Evolutionary psychology: Family ties (pp 727-731)
Humans may have evolved an inbuilt method for assessing genetic relatedness, a paper in this week’s Nature suggests.
Mechanisms for assessing genetic relatedness have been found in many species, but their existence in humans is controversial. John Tooby and colleagues now think that people use two distinct cues: if a potential sibling is younger, we watch to see how much time he or she spends with our mother; but the strategy doesn’t work if the sibling is older, in which case we assess how much time we have spent with that person.
The team predicted that siblings will be more likely to help each other out and feel disgust at the thought of incest than will non-siblings. Questionnaire responses from over 600 subjects back this up.
Debra Lieberman (University of Hawaii, Honolulu, HI, USA) Co-author
Tel: +1 808 956 9366; E-mail: [email protected]
 Particle acceleration: Wave up (pp 741-744; N&V)
Researchers describe a doubling of energy achieved by a plasma accelerator in Nature this week. The new technique could reduce the time and cost associated with high-energy particle physics research.
The energy frontier of particle physics is several trillion electronvolts, but few colliders will be able to achieve this. Plasma-based accelerators are attractive because they are capable of producing fields that are orders of magnitude larger than those used in conventional colliders. They generate a plasma wave that accelerates charged particles, but it was not clear whether this process could be sustained over the distances required for significant energy gain.
Chandrashekhar Joshi and colleagues find that it can: in their experiment, a metre-long plasma was able to boost the energies of some of the beam electrons by a factor of two. The team believe that this is a crucial step towards demonstrating the viability of using plasma accelerators in high-energy physics.
Chandrashekhar Joshi (University of California Los Angeles, CA, USA)
Please note the author is traveling and it may be easier to contact:
Mark Hogan (Stanford Linear Accelerator Center, Menlo Park, CA, USA) Co-author
Tel: +1 650 926 2951; E-mail: [email protected]
Robert Bingham (Rutherford Appleton Laboratory, Didcot, UK) N&V author
Tel: +44 1235 445 800; E-mail: [email protected]
 Ecology: Conservation strategy rethink (pp 757-760; N&V)
Conservation strategies that focus their efforts on maximizing species richness may be missing a trick, a paper in this week's Nature suggests. The evolutionary potential of an area is also important.
Félix Forest and colleagues studied the biodiversity and evolutionary relationships of plants growing in the Cape of South Africa, an undisputed biodiversity hotspot. A gradient of species richness exists across the area, with the western part home to around twice the density of plant species found in the eastern region.
The researchers particularly focused on evolutionary potential - areas with high evolutionary potential contain flora that, on average, are more distantly related to each other than flora in areas of low evolutionary potential. And species counts do not always correlate with evolutionary potential, they find. The more species-rich west has lower evolutionary potential than the east.
The results challenge long-lasting ideas about biodiversity assessments and patterns of species richness, and have important implications for conservation strategies.
Felix Forest (Royal Botanic Gardens, Kew, UK)
Tel: +44 20 8332 5372; E-mail: [email protected]
Arne Ø Mooers (Simon Fraser University, Burnaby, Canada) N&V author
Tel: +1 604 291 3979; E-mail: [email protected]
ALSO IN THIS ISSUE…
 Ultralow-power organic complementary circuits (pp 745-748)
 Charge- and size-based separation of macromolecules using ultrathin silicon membranes (pp 749-753; N&V)
 The Earth’s ‘hum’ is driven by ocean waves over the continental shelves (pp 754-756)
 Drosophila TCTP is essential for growth and proliferation through regulation of dRheb GTPase (pp 785-788)
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.
Auckland Park: 5
Port Elizabeth: 5
UNITED STATES OF AMERICA
La Jolla: 1
Los Angeles: 4
Menlo Park: 4
Santa Barbara: 3
For North America and Canada
Katie McGoldrick, Nature Washington
For Japan, Korea, China, Singapore and Taiwan
Mika Nakano, Nature Tokyo
For the UK/Europe/other countries not listed above
Helen Jamison, Nature London
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