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This press release is copyright Nature.
VOL.441 NO.7096 DATED 22 JUNE 2006
This press release contains:
* Summaries of newsworthy papers:
Earthquakes: When is the next big one on the southern San Andreas fault?
Developmental biology: Thymus bipotent precursor cells found
Hearing: Cell regeneration in mammalian inner ear
Behaviour: Eavesdropping yields benefits
Cancer: T-cell link to cancer
Astrophysics: The hole story
Pollination: Orchid has sexual intercourse with itself
Development: Cellular spaces fuse into blood vessels
Photonics: Pump up the bandwidth
And finally… Ancient lampreys are ‘design classic’
* Mention of papers to be published at the same time with the same embargo
* Geographical listing of authors
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[1] Earthquakes: When is the next big one on the southern San Andreas fault? (pp 968-971)
The San Andreas fault is notorious for its earthquakes. Yet there has been no major earthquake on the southern section of the fault, running to the east of Los Angeles, during the recorded history of European settlement in western California (the past 250 years). How much longer can the strain on this part of the fault build up without rupturing?
In this week’s Nature, Yuri Fialko attempts to answer that question with the help of data on the fault movements collected between 1985 and 2005. These radar and position (for example, GPS) measurements show how much the two sides of the fault have been moving past one another - the so-called slip rate. The bigger the average slip rate along a fault line, the more stress might be expected to be building up on parts of the fault that remain locked together, where a sudden rupture and release of the accumulated strain will happen in an earthquake.
Estimating the chance of such quakes is complicated, because movement across the fault does not necessarily have to lead to a build-up of stress. The stress might be getting released gradually rather than accumulating for a catastrophic event, owing to small movements called creep on the fault. Or it might be relaxed by compensating movements on other geological faults that branch off from the San Andreas fault, such as the San Jacinto fault to the south. Fialko found that the slip rates and accumulated stresses on the southern part of the San Andreas fault are indeed substantial: creep is not helping the fault to relax. The resulting strain is divided roughly equally between this and the San Jacinto fault - so the latter is not taking up most of the stress. Fialko concludes that there is a real likelihood that the long-dormant southern San Andreas fault could undergo a big earthquake before very much longer.
CONTACT
Yuri Fialko (Scripps Institution of Oceanography, La Jolla, CA, USA)
Tel: +1 858 822 5028; E-mail: [email protected]
[2] & [3] Developmental biology: Thymus bipotent precursor cells found (pp 988-991; 992-996; N&V)
Researchers have discovered that a single precursor cell can form both major cell types of the thymus. The finding, described in two papers in this week’s Nature, helps resolve a long-standing controversy over the origins of thymus epithelial cells and may have implications for the treatment of thymic disorders.
The thymus is critical to immune system functioning because it provides an environment for T cells to develop and mature. The small organ is separated into two compartments, the cortex and medulla, each containing functionally distinct populations of epithelial cells that are important for successive stages of T-cell development. But the origin of these cells is a subject of debate.
Graham Anderson and colleagues now show that cortical and medullary epithelial cells are both derived from the same precursor cell in embryonic mice. Thomas Boehm and colleagues show that a similar cell is present in mice shortly after birth, and that the bipotent precursor cell can give rise to a complete and functional thymus.
The findings hint that, in the future, transplants of these thymic epithelial precursor cells might help restore impaired thymus function.
CONTACT
Graham Anderson (University of Birmingham, UK) Author paper [2]
Tel: +44 121 414 6817; E-mail: [email protected]
Thomas Boehm (Max-Planck Institute of Immunobiology, Freiburg, Germany) Author paper [3]
Tel: +49 761 5108 328; E-mail: [email protected]
Hans-Reimer Rodewald (University of Ulm, Germany)
Tel: +49 731 5002 3360; E-mail: [email protected]
[4] Hearing: Cell regeneration in mammalian inner ear (pp 984-987)
Specialized hair cells in the inner ear that enable us to hear may be able to regenerate, a mouse study in Nature suggests. The finding may have therapeutic implications for certain types of deafness.
Neil Segil, Andrew Groves and colleagues have shown that supportive cells from the postnatal mouse inner ear retain the ability to divide and turn into new sensory hair cells in culture.
It’s known that some vertebrates, such as birds, are able to perform this feat in vivo, but the regenerative capacity of mammalian hair cells has so far been uncertain. The results strongly suggest that the mammalian cochlea retains the capacity for regeneration, but that the signals for regeneration are either absent or actively inhibited in vivo.
CONTACT
Neil Segil (House Ear Institute, Los Angeles, CA, USA)
Tel: +1 213 273 8082; E-mail: [email protected]
Andrew Groves (House Ear Institute, Los Angeles, CA, USA)
Tel: +1 213 989 6731; E-mail: [email protected]
[5] Behaviour: Eavesdropping yields benefits (pp 975-978; N&V)
Eavesdropping can be so much more than a way of finding out what your neighbours are up to. Some fish eavesdrop in order to assess the trustworthiness of others, and decide who to spend time with.
The cleaner fish Labroides dimidiatus can remove parasites from its clients or ’cheat’ by dining on the preferred option of client mucus. Yet clients rarely eat their cleaners, so why isn’t cheating rife?
The answer, say Redouan Bshary and Alexandra Grutter in this week’s Nature, lies in the ability of client fish to eavesdrop. The duo set up an experiment where client fish (Scolopsis bilineatus, the bridled monocle bream) were able to watch two cleaners. One appeared cooperative, dutifully nibbling away at parasites; however, no information was given on the second. Given the choice between two such cleaners, clients preferred to spend time close to the cooperative fish.
It’s thought that the clients build up an ‘image score’ of those they observe, and choose then to help those that score highly. The finding shows that complex social networks exist in the aquatic world, and helps set the stage for the evolution of altruism and reputation.
CONTACT
Redouan Bshary (University of Neuchatel, Switzerland)
Tel: +41 32 718 3005; E-mail: [email protected]
Lee Alan Dugatkin (University of Louisville, KY, USA)
Tel: +1 502 852 5943; E-mail: [email protected]
[6] Cancer: T-cell link to cancer (pp 1015-1019)
A link has been found between a particular type of gastrointestinal cancer and T-cell functioning. The discovery, reported in this week’s Nature, may have implications for patient treatment and aid the development of new therapies.
Children with the syndrome familial juvenile polyposis (FJP) develop gastrointestinal polyps that can sometimes become cancerous. Around half of all patients carry an inherited mutation in one copy of the SMAD4 gene, and it’s thought that cancer develops if the remaining copy becomes inactivated in the epithelial cells that line the gastrointestinal tract.
John Letterio and colleagues studied mice in which the Smad4 gene was deleted in specific cell types. When the gene was deleted in epithelial cells, mice did not develop cancer. But when the gene was deleted in T cells, which play a role in the immune system, mice developed epithelial cancers throughout the gastrointestinal tract.
Although the role of T cells in FJP has yet to be determined, the findings show that a genetic alteration in one cell type can induce cancer formation in a different tissue, increasing our understanding of the role of the microenvironment in tumour development.
CONTACT
John Letterio (National Cancer Institute, Bethesda, MD, USA)
Tel: +1 301 496 83 48; E-mail: [email protected]
[7] Astrophysics: The hole story (pp 953-955; N&V)
It is magnetism that allows matter to fall into black holes, according to new results reported by Jon Miller and colleagues in Nature this week.
The popular view of black holes is that their gravity sucks in all matter that comes close. But it isn't that simple, because an object held by the gravitational tug of a black hole would circulate in orbit indefinitely if there was no way of dissipating its angular momentum. Black holes that have companion stars tend to suck material from their partner into a disk that surrounds the black hole rather like the rings of Saturn, and that gas eventually goes into the black hole, so we know that something was removing angular momentum from it. That something could either be magnetic fields, or winds in the disk, but hitherto there was no evidence one way or the other.
Miller and colleagues have looked at a binary stellar system called GRO J1655−40, one member of which is a black hole. They find that some matter is constantly being pushed out of the black hole's accretion disk in a 'wind', and that this wind is created by the pressure in the disk caused by a magnetic field. The magnetic field makes the gas in the disk viscous, and creates the pressure that drives the wind. The wind itself carries away the angular momentum, allowing matter to fall into the black hole.
CONTACT
Jon Miller (University of Michigan, Ann Arbor, MI, USA)
Tel: +1 734 764 4185; E-mail: [email protected]
Daniel Proga (University of Nevada Las Vegas, NV, USA)
Tel: + 1 702 895 3507; E-mail: [email protected]
[9] Development: Cellular spaces fuse into blood vessels (AOP)
DOI: 10.1038/nature04923
***This paper will be published electronically on Nature's website on 21 June 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 22 June, but at a later date.***
Using sophisticated microscope imaging, Brant Weinstein and his colleagues present compelling evidence that blood vessels start out as intracellular sacs, or vacuoles, that fuse together. Blood vessels are lined by a layer of endothelial cells one-cell thick, but it has not been clear how these cells manage to create an interconnected tube, because it is difficult to watch them grow deep within living animals.
The team used two-photon imaging in which vacuoles are fluorescently labelled in clear zebrafish embryos. They watched endothelial tubes assemble and compared the results with those from human endothelial cells grown in three dimensions in the laboratory. The results, appearing online this week in Nature, support the idea that intracellular vacuoles form and fuse together within and between cells, leading to the formation of a tube that spans multiple cells.
CONTACT
Brant Weinstein (National Institute of Child Health and Human Development, Bethesda, MD, USA)
Tel: +1 301 435 5760; E-mail: [email protected]
[10] Photonics: Pump up the bandwidth (pp 960-963)
Using all-optical devices on a chip, rather than electronic circuits, promises to boost the speed of information processing, and now scientists have developed an optical amplifier based on silicon that works across a wide range of frequencies. The research, published in this week's Nature, could help to bring practical all-optical information processing closer.
As computer manufacturers are already very good at producing silicon chips, scientists have been trying to develop optical processing elements that are based on silicon. Optical amplifiers have been developed using silicon, but they only work for a very narrow range of frequencies of light.
Alexander Gaeta and colleagues have now developed a silicon waveguide that can amplify light waves with a relatively broad range of frequencies, relying on a process called phase-matched four-wave mixing. This should allow much higher volumes of information to be processed by the same chip, and makes it easier to add other devices, such as delays and switches, to the optical circuits.
CONTACT
Alexander Gaeta (Cornell University, Ithaca, NY, USA)
Tel: +1 607 255 9983; E-mail: [email protected]
ALSO IN THIS ISSUE…
[12] Genetic mechanisms and evolutionary significance of natural variation in Arabidopsis (pp 947-952)
[13] The giant electromechanical response in ferroelectric relaxors as a critical phenomenon (pp 956-959)
[14] The Southern Ocean biogeochemical divide (pp 964-967)
[15] Experience-dependent and cell-type-specific spine growth in the neocortex (pp 979-983)
[16] Increased cell-to-cell variation in gene expression in ageing mouse heart (pp 1011-1014)
[17] Lasers producing tailored beams (pp 946)
ADVANCE ONLINE PUBLICATION
***These papers will be published electronically on Nature's website on 21 June 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 22 June, but at a later date.***
[18] An ARC/Mediator subunit required for SREBP control of cholesterol and lipid homeostasis
DOI: 10.1038/nature04942
[19] Mesodermal Wnt2b signalling positively regulates liver specification
DOI: 10.1038/nature04888
[20] Enzymatic activation of voltage-gated potassium channels
DOI: 10.1038/nature04880
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
Melbourne: 19
St Lucia: 5
CHINA
Beijing: 11
Guangzhou: 8
Hefei: 8
Shenzen: 8
CZECH REPUBLIC
Prague: 13
GERMANY
Freiburg: 3
Konstanz: 3
Munich: 16
JAPAN
Kyoto: 17
Mizosaki: 17
NETHERLANDS
Amsterdam: 7
Bilthoven: 16
Utrecht: 18
SLOVENIA
Ljubljana: 13
SWITZERLAND
Lausanne: 15
Neuchatel: 5
UNITED KINGDOM
Birmingham: 2
Cambridge: 7
London: 19
UNITED STATES OF AMERICA
California
Berkeley: 18
La Jolla: 1
Los Angeles: 4
Novato: 16
San Francisco: 19
Illinois
Champaign: 18
Indiana
Indianapolis: 6
Kansas
Lawrence: 11
Maryland
Bethesda: 6, 9
College Park: 7
Frederick: 6
Largo: 18
Massachusetts
Boston: 18
Cambridge: 7, 14, 18, 19
Charlestown: 18
Michigan
Ann Arbor: 7
New Hampshire
Hanover: 18
New Jersey
Princeton: 14
New York
Cold Spring Harbor: 15
Ithaca: 10
North Carolina
Durham: 12
Pennsylvania
Philadelphia: 20
Rhode Island
Providence: 12
Texas
College Station: 9
San Antonio: 16
Washington
Pullman: 18
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For Japan, Korea, China, Singapore and Taiwan
Rinoko Asami, Nature Tokyo
Tel: +81 3 3267 8751; E-mail: [email protected]
For the UK/Europe/other countries not listed above
Helen Jamison, Nature London
Tel: +44 20 7843 4658; E-mail [email protected]
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