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This press release is copyright Nature. VOL.440 NO.7085 DATED 6 April 2006
This press release contains:
Summaries of newsworthy papers:
* Astronomy: Supernova's dusty residue spied
* Zoology: Some mole-rats are programmed for laziness
* Planetary science: Oxygen mystery gets more mysterious
* Cancer: Targeting leukaemia stem cells
* Avian flu: Cat among the chickens
* Anthropology: Neolithic dental drill
* Genetics: Genome of wastewater-treatment bacterium extracted from the sludge
* Development: Motor protein drives asymmetry
* Materials science: Liquid silicon for spray-on chips
* And finally… Escapologist worms show how to burrow out of trouble
* Mention of papers to be published at the same time with the same embargo
* Geographical listing of authors
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[1] Astronomy: Supernova's dusty residue spied (pp772-775)
Astronomers have found a dusty disk around a pulsar for the first time, they report in this week's Nature. This discovery was predicted by current theories of how supernovae happen.
At the end of their lives, stars can collapse under their own gravity to leave an incredibly dense core whilst flinging material far out into space. This supernova process can generate various types of neutron star, such as a rapidly-spinning pulsar. If the star has enough mass it can even turn into a black hole, an object with such powerful gravity that not even light can escape its clutches.
Deepto Chakrabarty and colleagues used NASA's Spitzer Space Telescope to look at a young X-ray pulsar, and saw a cool disk of material around it glowing in infrared light. They argue that this is a so-called 'fallback' disk, material that has not quite escaped from the supernova.
Some theories suggest that this fallback material could push a neutron star over its stability limit and turn it into a black hole, and the observations should help to decide whether this is possible. The authors add that planets could eventually form from such disks.
CONTACT
Deepto Chakrabarty (Massachusetts Institute of Technology, Cambridge, MA, USA)
Tel: +1 617 253 3840; E-mail: [email protected] <mailto:[email protected]>
[2] Zoology: Some mole-rats are programmed for laziness (pp795-797)
There is such a thing as inherent laziness, at least for Damaraland mole-rats (Cryptomys damarensis). Zoologists have identified the existence of physiologically distinct castes of workers in this animal, one of only two mammal species that lives in cooperatively breeding colonies similar to those of many insects.
Some mole-rats are industrious, whereas some are fat and lazy. Now, by studying the creatures' energy demands and activity, Michael Scantlebury and colleagues have discovered that the two lifestyles are indeed distinct, rather than being opposite ends of a behavioural spectrum.
Industrious mole-rats are active year-round and accomplish 95% of the colony's chores, the researchers report in this week's Nature. Infrequent workers, on the other hand, have lower energy demands and spend much of their time eating. However, their energy expenditure rockets beyond that of their conscientious colleagues after a bout of rainfall, when digging is easier and opportunities abound to disperse and reproduce. Scantlebury and his team suspect that the lazy mole-rats are colony parasites, snaffling food during lean times and striking out on their own when times are easier.
CONTACT
Michael Scantlebury (University of Pretoria, Pretoria, South Africa)
Tel: +27 12 420 4872; E-mail: [email protected] <mailto:[email protected]>
Nigel Bennett (Univeristy of Pretoria, Pretoria, South Africa) Co-author
Tel: +27 12 420 2538; E-mail: [email protected] <mailto:[email protected]>
[3] Planetary science: Oxygen mystery gets more mysterious (pp776-778; N&V)
Scientists trying to work out the chemical composition of the protoplanetary soup that spawned our Solar System have stumbled upon a mystery. The Sun's outer layers appear to have less of the most common isotope of oxygen than Solar System rocks, the researchers report in this week's Nature.
The Sun's outer reaches are thought to have the same chemical make-up as the primitive Solar System. These elements are blown outwards in the flow of charged atoms that make up the solar wind. Some of these atoms embed themselves in Moon rocks and soil such as that returned to Earth by the Apollo missions, allowing scientists to indirectly study the origins of our planet.
Trevor Ireland and colleagues have now analysed the different isotopes of oxygen (16O, 17O and 18O) in the samples. The most common isotope, 16O, is usually about 500 times more abundant than the other two forms combined. But the scientists found that their samples had a little bit less 16O than they expected.
"Their results cannot, however, be explained within our current understanding of oxygen isotopes and the structure of the Sun," comments Gary R. Huss in a related News and Views article. The research follows previous work, also published in Nature, suggesting that the Sun's outer layers actually contained more 16O than Solar System rocks.
CONTACT
Trevor Ireland (The Australian National University, Canberra, Australia)
Tel: +61 261 255 172; E-mail: [email protected] <mailto:[email protected]>
Gary Huss (University of Hawai'I, Honolulu, HI, USA)
Tel: +80 8 956 9342; E-mail: [email protected] <mailto:[email protected]>
[4] Cancer: Targeting leukaemia stem cells (AOP)
DOI: 10.1038/nature04703
ADVANCE ONLINE PUBLICATION
***This paper will be published electronically on Nature's website on 5 April 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 6 April, but at a later date.***
Cancer stem cells - cells thought to initiate and maintain tumours - share many properties with normal stem cells, making it difficult to design cancer treatments that effectively target cancer stem cells without killing normal stem cells. This is problematic as damaging, for example, haematopoietic stem cells during the treatment of leukaemia would severely compromise the immune system.
In a paper to be published online this week by Nature, Sean Morrison and colleagues study a tumour suppressor protein frequently inactivated in leukaemia and other cancers. Called PTEN, this protein normally inhibits the phosphatidylinositol-3-OH kinase (PI(3)K) signalling pathway and its downstream effector mTOR, thus limiting cell proliferation and survival.
The researchers deleted Pten in blood cells of mice and found that although this led to the development of leukaemias, normal haematopoietic stem cells became depleted because they lost the ability to maintain themselves. Treatment of these mice with the mTOR inhibitor rapamycin prevented the generation of leukaemic stem cells and leukaemia development, and reduced the number of leukaemia stem cells in already established leukaemias. Moreover, rapamycin restored the function of normal haematopoietic stem cells, including their ability to replenish immune cells in bone-marrow-depleted mice. Therapeutically targeting pathways that distinguish between normal stem cell self-renewal and cancer stem cell function in the same tissue may make it possible to target tumours without damaging normal stem cells.
CONTACT
Sean Morrison (University of Michigan, Ann Arbor, MI, USA)
Tel: +1 734 647 6261; E-mail: [email protected] <mailto:[email protected]>
Avian flu: Cat among the chickens (pp741-742)
In 2004, the first report of a domestic cat dying from the avian influenza H5N1 virus in Thailand hit the airwaves. Since then, a number of cases have been reported around the globe, including the death and euthanasia of 147 captive tigers fed virus-infected chicken carcasses. As an increasing number of feline fatalities are reported worldwide, a Commentary in this week’s Nature urges that we reconsider the role that cats play in the spread and evolution of the avian influenza virus.
Osterhaus and colleagues discuss the latest reports and experimental studies that underline the vulnerability of cats to H5N1 virus infection and the risks that cats pose to agencies fighting its global spread. They highlight that cats become infected with the virus through contact with domestic and wild birds, and then excrete the virus from the respiratory and digestive tract, sometimes transmitting infection to other cats. They also note that cats fed virus-infected chickens can be infected directly through the gut - a novel route for influenza transmission in mammals. Despite this evidence, the authors argue that the impact of cats on the epidemiology of the avian influenza virus is still being overlooked by key organizations such as the World Health Organization (WHO).
The authors conclude that they cannot rule out the possibility of the virus mutating into a more dangerous strain in feline and other mammalian hosts, and suggest increased surveillance and precautions to be taken to prevent the virus leaping to humans.
CONTACT
Albert Osterhaus (Erasmus MC, Rotterdam, Netherlands)
Tel: +31 10 408 8066; E-mail: [email protected] <mailto:[email protected]>
[5] Anthropology: Neolithic dental drill (p755)
Evidence of prehistoric trips to the dentist has been unearthed in an early Neolithic cemetery in Pakistan. Teeth dating as far back as 9,000 years ago show clear signs of having undergone drilling during their owner’s lifetime.
The discovery, which is reported in a Brief Communication in this week’s Nature, was made by Macchiarelli and colleagues during excavations of graves at Mehrgarh in Baluchistan. A total of eleven drilled permanent crowns were found, with one example showing evidence of a complex procedure involving tooth enamel removal followed by micro-tool carving of the cavity wall. Four of the teeth show signs of decay associated with the drilled hole, indicating that the intervention may have been therapeutic. The authors note that this sort of dental ‘treatment’ continued for about 1,500 years, before the practice was stopped in this area.
Unlike the metal drills of today, the authors believe that flint heads were the Neolithic drill of choice. Flint drill heads are found in abundance at the Mehrgarh site, among assemblages of beads made of bones, shell and turquoise. The authors suggest that the skills developed by bead craftsmen also worked well on teeth.
CONTACT
Roberto Macchiarelli (Universite de Poitiers, Poitiers, France)
Tel: +33 549 45 37 78; E-mail: [email protected] <mailto:[email protected]>
[6] Genetics: Genome of wastewater-treatment bacterium extracted from the sludge (pp790-794)
Geneticists have used the relatively new technique of environmental genomics - the sequencing of an organism's genome using samples taken directly from its natural environment - to compile the genetic sequence of the unusual bacterium Kuenenia stuttgartiensis. This microbe, which could potentially be used in wastewater treatment, is the most complex species sequenced to date using an environmental genomics approach.
Researchers led by Mike Jetten and Michael Wagner pieced together the genome by sampling a 'bioreactor' containing a community of many microbial species all growing together. K. stuttgartiensis grows so slowly that it took a year to attain large enough numbers for effective sampling. Details of the bacterium's genome and its metabolism appear in this week's Nature.
This work elucidates some of the weird and wonderful metabolic tricks that K. stuttgartiensis has up its sleeve, the researchers add. The species is an 'anammox' bacterium, meaning that it gets its energy through the anaerobic oxidation of ammonium - which makes it potentially valuable in mopping up the nitrogen-containing compounds found in sewage.
CONTACT
Mike Jetten (Radboud University Nijmegen, Nijmegen, The Netherlands)
Tel: +31 24 365 2941; E-mail: [email protected] <mailto:[email protected]>
[7] & [8] Development: Motor protein drives asymmetry (pp803-807 & 798-802)
Biologists have long been fascinated by how an embryo that starts out bilaterally symmetrical ends up as an asymmetric organism, with internal organs positioned to the left or right of the central axis. In this week’s Nature, two groups of researchers reveal that an unusual motor protein could be responsible for asymmetry in invertebrates.
Working with fruitflies, teams led by Stephane Noselli and Kenji Matsuno show that mutations in the Myo31DF gene flip the normal handedness of the gut and genitalia in adult flies. Myo31DF is only the second gene identified to be capable of such a feat. The protein it encodes is a form of myosin that attaches to the cell’s internal skeleton and may help to ferry molecules important for establishing asymmetry to their appropriate positions - perhaps distinguishing one side of a cell from the other in the process. Such asymmetries at the level of the cell could lead to the development of asymmetrically positioned organs. This discovery may shed light on how asymmetry arises in other species, including humans.
CONTACT
Stephane Noselli (Institute of Signalling, Nice, France) Paper [7]
Tel: +33 4 92 07 64 33; E-mail: [email protected] <mailto:[email protected]>
Kenji Matsuno (Tokyo University of Science, Chiba, Japan) Paper [8]
Tel: +81 4 7122 9714; E-mail: [email protected] <mailto:[email protected]>
[9] Materials science: Liquid silicon for spray-on chips (pp 783-786; N&V)
A method for making silicon devices could make current energy-hungry and expensive processing methods a thing of the past. Masahiro Furusawa and colleagues describe in this week’s Nature how they make crystalline silicon films, of sufficient quality for some microelectronics applications, from a kind of 'liquid silicon' that can be coated onto a surface either by spinning the surface to spread the liquid or by squirting the liquid from an ink-jet printer.
Making microelectronic devices on silicon chips is a high-tech business, done in labs that need to be kept so clean they look as though they are designed for handling highly poisonous chemicals. Layers of silicon and other semiconductors are typically deposited onto chips under high vacuum, and the faintest whiff of contaminating gas or dust could ruin them.
Furusawa’s 'soft processing' of silicon doesn't need high vacuums, high temperatures or ultra-clean environments. It produces so-called polycrystalline silicon - a mosaic of flat microcrystals - with electrical behaviour comparable to that of polycrystalline silicon thin films made by the expensive conventional methods.
The 'liquid silicon' used by Furusawa and colleagues is actually a form of polysilane, composed of molecules in which silicon atoms are linked into short chains and capped with hydrogen atoms. To make this substance, the researchers started with molecules of cyclopentasilane, containing five silicon atoms joined in a ring. Exposing this liquid compound to ultraviolet light breaks open some of the rings and lets the chains link into longer ones. The researchers then dilute this mixture with an organic solvent like toluene, and spread or spray it onto a surface. Baking the liquid film at around 500 degrees Celsius converts it to polycrystalline silicon.
CONTACT
Masahiro Furusawa (Seiko Epson Corporation, Nagano-ken, Japan)
Tel: +81 266 62 8455; [email protected] <mailto:[email protected]>
Lisa Rosenberg (University of Victoria, Victoria, Canada)
Tel no: +1 250 721 7173; E-mail: [email protected] <mailto:[email protected]>
[10] And finally… Escapologist worms show how to burrow out of trouble (p756)
The gordian worm (Paragordius tricuspidatus) knows how to escape from a tight spot. The parasitic worm, which spends much of its life inside an insect host, can wriggle free even if the hapless host is swallowed by a predator.
This is the first time a parasite has demonstrated such an ability, say Fleur Ponton and colleagues, who describe the phenomenon in a Brief Communication in this week’s Nature.
The worms must escape from their insect hosts in order to breed. But as the worms escape from the hosts - a process that can take up to 10 minutes - the insects are particularly vulnerable to predators as they writhe on the pond surface. However, although the insects are doomed, the indefatigable worms later appear from the frogs’ mouths or the fishes’ gills, as shown in a series of stunning videos presented as supplements to the paper.
CONTACT
Fleur Ponton (Centre IRD de Montpellier, Montpellier, France)
Tel: +33 467 41 63 73; E-mail: [email protected] <mailto:[email protected]>
ALSO IN THIS ISSUE…
[11] Quantum interference between two single photons emitted by independently trapped atoms (779-782)
[12] Increased Arctic cloud longwave emissivity associated with pollution from mid-latitudes (pp787-789)
[13] Omega-3 and omega-6 fatty acids stimulate cell membrane expansion by acting on syntaxin 3 (pp813-817)
[14] Semi-conservative DNA replication through telomeres requires Taz1 (pp824-828)
[15] Proton-coupled electron transfer drives the proton pump of cytochrome c oxidase (pp829-832)
[16] Crystal structure of the CorA Mg21 transporter (pp833-837)
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
Canberra: 3
Melbourne: 3
AUSTRIA
Vienna: 6
CANADA
Toronto: 16
DENMARK
Copenhagen: 10
FINLAND
Helsinki: 15
FRANCE
Arles: 10
Evry: 6
Montpellier: 10
Nice: 8, 7
Orsay: 11
Paris: 5
Poitiers: 5
GERMANY
Freising: 6
Garching: 6
Neuherberg: 6
HUNGARY
Szeged: 7
ITALY
Bologna: 5
Rome: 5
JAPAN
Chiba: 8
Kanagawa: 9
Mie: 9
Nagano-ken: 9
Tokyo: 8
Yamaguchi: 8
MEXICO
Yucatan: 5
SOUTH AFRICA
Pretoria: 2
SWITZERLAND
Zurich: 6
THE NETHERLANDS
Delft: 6
Nijmegen: 6
UNITED KINGDOM
Aberdeen: 2
Brighton: 2
Cambridge: 13
London: 14
Oxford: 16
UNITED STATES OF AMERICA
California - Los Angeles: 4
- San Francisco: 14
Illinois - Argonne: 16
Kansas - Lawrence: 5
Massachusetts - Cambridge: 1, 16
Michigan - Ann Arbor: 4
Texas - Houston: 3
Utah - Salt Lake City: 12
PRESS CONTACTS…
For North America and Canada
Katie McGoldrick, Nature Washington
Tel: +1 202 737 2355; E-mail: [email protected] <mailto:[email protected]>
For Japan, Korea, China, Singapore and Taiwan
Rinoko Asami, Nature Tokyo
Tel: +81 3 3267 8751; E-mail: [email protected] <mailto:[email protected]>
For the UK/Europe/other countries not listed above
Ruth Francis, Nature London
Tel: +44 20 7843 4562; E-mail [email protected] <mailto:[email protected]>
Victoria Picknell, Nature London
Tel: +44 20 7843 4502; E-mail: [email protected]
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