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Porous material has huge, handed holes; Understanding antibodies; The Dune thing; Diatoms delve deep for nutrients to stay alive; Human protein interactions go large scale; Corrupting the bacterial quorum; Quicksand won't suck you right in

This press release is copyright Nature. Its use is granted only for journalists and news media receiving it directly from Nature. VOL.437 NO.7059 DATED 29 SEPTEMBER 2005 * Animal behaviour: How water-walking insects defy gravity * Robotics: Replicating machines, DNA style * Astrophysics: Lost (and found) in space * Botany: First potential receptor for plant hormone gibberellin * Oceanography: Malnutrition at sea * Climate: Acidifying oceans could doom seashells and corals sooner than expected * Materials: Porous material has huge, handed holes * Virology: Understanding antibodies * Physical sciences: The Dune thing * Ecology: Diatoms delve deep for nutrients to stay alive * Cell biology: Human protein interactions go large scale * Microbiology: Corrupting the bacterial quorum * And finally... Quicksand won't suck you right in * Mention of papers to be published at the same time with the same embargo * Geographical listing of authors Editorial contacts: While the best contacts for stories will always be the authors themselves, in some cases the Nature editor who handled the paper will be available for comment if an author is unobtainable. Editors are contactable via Ruth Francis on +44 20 7843 4562. Feel free to get in touch with Nature's press contacts in London, Washington and Tokyo (as listed at the end of this release) with any general editorial inquiry. Warning: This document, and the Nature papers to which it refers, may contain information that is price sensitive (as legally defined, for example, in the UK Criminal Justice Act 1993 Part V) with respect to publicly quoted companies. Anyone dealing in securities using information contained in this document or in advanced copies of Nature's content may be guilty of insider trading under the US Securities Exchange Act of 1934. The Nature journals press site is at <http://press.nature.com> * PDFs for the Articles, Letters, Progress articles, Review articles, Insights and Brief Communications in this issue will be available on the Nature journals press site from 1400 London time / 0900 US Eastern time on the Friday before publication. * PDFs of News & Views, News Features, Correspondence and Commentaries will be available from 1400 London time / 0900 US Eastern time on the Monday before publication PICTURES: While we are happy for images from Nature to be reproduced for the purposes of contemporaneous news reporting, you must also seek permission from the copyright holder (if named) or author of the research paper in question (if not). HYPE: We take great care not to hype the papers mentioned on our press releases, but are sometimes accused of doing so. If you ever consider that a story has been hyped, please do not hesitate to contact us at press@nature.com <mailto:press@nature.com>, citing the specific example. PLEASE CITE NATURE AND OUR WEBSITE www.nature.com/nature AS THE SOURCE OF THE FOLLOWING ITEMS. IF PUBLISHING ONLINE, PLEASE CARRY A HYPERLINK TO http://www.nature.com/nature [1] Animal behaviour: How water-walking insects defy gravity (pp733-736) Ponds and puddles might appear flat to the human eye, but to a tiny insect they can be a rugged and treacherous terrain. Researchers have now shown that water-walking insects use a unique mode of propulsion to climb the steeply sloping meniscus at the edge of a puddle, despite it being a steep, slippery wall of water. Using high-speed video, David Hu and John Bush captured the meniscus-climbing action of three water-walking insect species. As the researchers report in this week's Nature, the two-millimetre-long insects adopt a special posture to create capillary forces that drive them up the slope at almost thirty body lengths per second , without any need to move their legs during the journey. They do this by virtue of their 'wetting' front and rear legs, which can pull at the surface of the water and raise it into a tiny peak. Meanwhile, the central pair of legs presses down on the water, forming dimples in its surface. Because the insects are so small, these perturbations create capillary forces that suck them up the slope, similar to the way in which water is sucked up a thin tube by the force of its own surface tension. CONTACT John Bush (Massachusetts Institute of Technology, Cambridge, MA, USA) Tel: +1 857 991 9280; E-mail: bush@math.mit.edu [2] Robotics: Replicating machines, DNA style (p636) Welcome the robots that can copy themselves - and fix any mistakes they might make. Electromechanical engineers have created a set of machines that can fashion copies of themselves from randomly circulating components, much as DNA copies itself from the chemical building blocks floating around in biological cells. The system starts with a single template string made up of two different colours in a certain sequence, explain its creators Joseph M. Jacobson and colleagues in a Brief Communication in this week's Nature. The string floats around on a cushion of air - along the same lines as an air-hockey table - surrounded by loose, randomly moving building blocks of the two colours. When two blocks come into contact, they can latch together. But the strings are also fitted with an electronics package that checks the colour of the neighbouring block, and can trigger them to unlatch if the sequence is not correct. Thus, over time, the number of strings matching the original template can grow exponentially, limited only by the supply of building blocks. If the process can be sufficiently miniaturized, the authors hope it could prove valuable in automating industrial assembly processes. CONTACT Joseph M. Jacobson (Massachusetts Inst of Technology, Cambridge, MA, USA) Tel: +1 617 253 7209; E-mail: jacobson@media.mit.edu [3] Astrophysics: Lost (and found) in space (pp707-710) Dark matter - the mysterious stuff that seems to comprise most of the matter in the Universe - was recently suggested to be even more mysterious, because of its apparent absence from some galaxies. But it may be there after all, say Avishai Dekel and colleagues in this week's Nature. They have investigated the claim, made a few years ago, that the slow speeds of outlying stars in elliptical galaxies are inconsistent with the presence there of dark matter. The researchers show that these stars can have low velocities even if the galaxies contain large amounts of dark matter. Dark matter is so-called because it can't be seen directly. But astronomers have inferred that it permeates galaxies because the motions of stars seem to show that they are being gravitationally attracted by something more than all the other visible stars and dust. Over four-fifths of the mass in the Universe seems to be made of this stuff. No one knows what it consists of, but it doesn't seem to be any of the known forms of matter. Elliptical galaxies, some of which are probably formed by the merging of smaller galaxies, ought in this picture to contain just as much dark matter as any other galaxy. But the paths of the slow-moving stars that have been seen in elliptical galaxies don't seem to bear the imprint of dark matter's gravitational tug, which was expected to speed them up. Dekel and colleagues have now performed computer simulations of the merging events in which elliptical galaxies are formed, and they find that these processes can produce stars in elongated orbits that move slowly even when the merged galaxies contain their usual complement of dark matter. So it may still be unexplained - but it does seem to be there after all. CONTACT Avishai Dekel (Hebrew University, Jerusalem, Israel) Tel: +972 2 6584100; E-mail: dekel@astro.huji.ac.il [4] Botany: First potential receptor for plant hormone gibberellin (pp693-698; N&V) The plant hormone gibberellin plays an essential role in plant germination, stem elongation and flower development. But until now, no one had isolated a receptor for this critical hormone. This week, Makoto Matsuoka and colleagues provide evidence that the GID1 gene in rice encodes an unknown soluble protein receptor for this hormone. The researchers describe a mutant variety of rice that cannot produce fertile flowers, among other abnormalities. By comparing its DNA with that from other varieties of rice, they show that abnormalities in the GID1 gene disrupt the plant's ability to sense gibberellin. In another part of the experiment, they show that overexpression of the gene product results in long, spindly plants - the expected result from oversensitivity to the hormone. The results of the study, which highlight the first soluble gibberellin receptor, appear this week in Nature. "The successful hunt carried out by [Ueguchi-Tanaka et al.] not only takes the plant hormone debate further, but the enhanced molecular understanding of gibberellin signalling may also presage a new green revolution," write Dario Bonetta and Peter McCourt in a related News and Views article. CONTACT Makoto Matsuoka (Nagoya University, Aichi, Japan) Tel: +81 52 789 5218; E-mail: makoto@nuagr1.agr.nagoya-u.ac.jp Peter McCourt (University of Toronto, Canada) Tel: +1 416 978 0523; E-mail: mccourt@botany.utoronto.ca [5] Oceanography: Malnutrition at sea (pp687-692; N&V) How does life in the oceans get its nutrients? Conventional thinking on this issue is literally knocked sideways by findings reported this week in Nature by Jaime Palter and co-workers. They show that, while the availability of nutrients for plankton growth is normally considered to depend on the vertical circulation of water masses, horizontal water movements can also exert a crucial influence. Understanding the factors that limit plankton growth - and thus the base of the oceanic food web - is vitally important for predicting, for example, changes in fish stocks. Palter and colleagues find that water a few hundred metres below the surface of the subtropical North Atlantic Ocean (east of the Gulf of Mexico) can become depleted in nutrients because of an influx of nutrient-poor water from a region along the north edge of this part of the ocean. The subtropical North Atlantic contains a circulating current called a gyre. Nutrients, on which plankton growth depends, are delivered to the gyre by vertical, conveyor-belt circulation of water, driven in part by winds at the ocean surface. The upwelling water tends to be rich in the chemical compounds such as nitrate and phosphate that organisms need for growth. The new findings, however, reveal that this nutrient supply can be undermined by water penetrating into the gyre from the north thanks to a process called North Atlantic Subtropical Mode Water (STMW) formation. From January to around April each year, there is a 'bloom' of plankton in the region of STMW formation, which eats up all the nutrients in that part of the ocean. This water, the researchers show, can consequently have much lower nutrient concentrations than those typical of the subtropical North Atlantic. The depleted water then gets carried southwards into the subtropical gyre, introducing low nutrient levels that can be seen at least 2,000 kilometres to the south. A related News & Views article by Marina Lévy accompanies this research. CONTACT Jaime Palter (Duke University, Durham, NC, USA) Tel: +1 919 684 6227; E-mail: jbp3@duke.edu Marina Lévy (Institut Pierre Simon LaPlace, Paris, France) Tel: +33 1 44 27 2707; E-mail: marina@lodyc.jussieu.fr [6] Climate: Acidifying oceans could doom seashells and corals sooner than expected (pp681-686) As carbon dioxide in the atmosphere dissolves into the Earth's oceans, the water becomes more acidic and the concentration of carbonate ions is reduced, threatening to prevent certain marine life and corals from growing their chalky shells. Research in this week's Nature predicts that if carbon dioxide emission from burning fossil fuels continues at its present rate, oceanic ecosystems could be badly hit within decades, not centuries as previously suggested. James C. Orr and colleagues used computer models to predict carbonate ion concentrations in the ocean over the next century. These carbonate ions are taken up by many sea creatures to form aragonite, a form of calcium carbonate used to make their shells and external skeletons. But the scientists' projections suggest that Southern Ocean waters, as well as parts of the subarctic Pacific Ocean, will be depleted of aragonite by 2100 because of rising carbon dioxide levels. The authors assessed the biological impact of these predictions by exposing a species of swimming snail, known as a pteropod, to conditions that simulated Southern Ocean surface waters in 2100. They found that the snails' shells dissolved markedly within 48 hours of exposure to these conditions. The scientists say that these creatures may not be able to adapt quickly enough to survive in such conditions, and their demise could affect the fish and whales that feed on them. Similar changes could also affect cold water corals that provide an important habitat for fish. CONTACT James C. Orr (Laboratoire des Sciences du Climat et de l'Environnement, Gif-sur-Yvette, France) Tel: +33 1 69 08 77 23; E-mail: orr@cea.fr [7] Materials: Porous material has huge, handed holes (pp716-719; N&V) Porous metal oxides are widely used as catalysts to speed up chemical reactions, and a family of germanium oxides reported in this week's Nature could prove to be the most versatile yet. Xiaodong Zou and colleagues found that their germanium oxides contained larger pores than other metal oxides, potentially allowing chemicals to sneak inside more easily to undergo reactions. Unusually for a metal oxide, the walls of the pores are crystalline, which should boost its chemical activity. It also allowed the scientists to accurately work out the pores' shapes. This revealed that the channels twisted either clockwise or anticlockwise, like the thread of a nut. By blocking off one set of channels, the scientists created a material where all the channels spiralled in the same direction. This could be a useful environment for making chiral molecules, such as those found in therapeutic drugs, which can come in left- or right-handed forms depending on the spatial arrangement of their atoms. A related News & Views article by Hermann Gies accompanies this research. CONTACT Xiaodong Zou (Stockholm University, Sweden) Tel: +46 8 16 23 80; E-mail: zou@struc.su.se Hermann Gies (Ruhr-Universität Bochum, Germany) Tel: +49 234 322 3512; E-mail: Hermann.Gies@ruhr-uni-bochum.de [8] Virology: Understanding antibodies (pp764-768) Researchers in this week's Nature report on an antibody involved in stopping West Nile virus at a cellular level before it has a chance to take hold. They study how the antibody binds to the virus and inhibits infection, after the virus has attached itself to the cell surface. The findings could help in the development of vaccines for associated viruses such as Japanese encephalitis, yellow fever and dengue viruses - the latter infects about 50 million people each year and currently has no authorised vaccine. West Nile virus is a bird pathogen, but since it was first reported in the United States in 1999, there have been more than 16,000 reported cases of human infection, with more than 650 deaths. As West Nile virus is a flavivirus, the findings should be useful for developing vaccine strategies against other members of this family - some of which are even more damaging to humans. Daved Fremont and colleagues analysed the interaction of an antibody, E16, with amino acids belonging to one surface protein of the virus. The team found that E16 waits until the virus has attached itself to the host cell's surface, then sneakily prevents the fusion process by blocking the virus-triggered conformational changes in the host cell. Until now, researchers had assumed that protective antibodies simply blocked the initial attachment. This work shows E16 can block infection regardless of the method of entry into the cell, making it a key candidate for improved vaccine design strategies. CONTACT Daved Fremont (Washington University, St Louis, MO, USA) Tel: +1 314 747 6547; E-mail: fremont@wustl.edu [9] Physical sciences: The Dune thing (pp720-723) Moving sand dunes - known as barchans - are fundamentally unstable, according to research published in Nature this week. Barchans are crescent-shaped dunes that move faster than most other dune types over desert surfaces. The dynamic processes responsible for the evolution of barchan dune fields, however, remain poorly understood. Using a combination of data from a three-year field study and a simple theoretical model, Bruno Andreotti and colleagues now show that that dune collisions and changes in wind direction destabilize the dunes, generating surface waves that can produce new barchans of a smaller size by breaking the horns of the large dunes. The creation of these new dunes prevents dune fields from merging into a single giant dune, and therefore plays a fundamental role in the development of barchan dune patterns. CONTACT Bruno Andreotti (Ecole Supérieure de Physique et Chimie Industrielles, Paris, France) Tel: +33 1 40 79 58 09; E-mail: andreotti@pmmh.espci.fr [10] Ecology: Diatoms delve deep for nutrients to stay alive (pp728-732) During spring, the North Atlantic Ocean teems with tiny diatoms - unicellular photosynthetic plankton that fashion cell walls from silicate minerals dissolved in the water. But researchers had been unsure how these tiny creatures keep thriving in such huge numbers during periods when silicate is not readily available at the ocean surface. The answer is that they 'mine' it from deeper waters, reports a team led by John Allen in this week's Nature. Silicate periodically rises from the deep at ocean 'fronts' such as the Iceland-Faeroes Front (IFF), one of the boundaries between Atlantic and Arctic waters. As long as there are enough other nutrients, such as nitrate, to sustain the diatoms, this replenishment enables them to keep growing, the team reports. This discovery, made by sampling and studying waters from the IFF, shows that the ocean fronts are more dynamic regions than experts realized, the authors add. This could potentially help to explain how plankton supply so much carbon to deep-water ecosystems when they die off. Allen's team also notes that similar frontal systems could supply other nutrients, such as phosphate or iron, from the deep. CONTACT John Allen (National Oceanography Centre, Southampton, UK) No telephone number at present - please use the following email address while we try to find a contact phone number: E-mail: jta@sea.soc.soton.ac.uk [11] Cell biology: Human protein interactions go large scale (DOI: 10.1038/nature04209) ***This paper will be published electronically on Nature's website on 28 September 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 29 September, but at a later date.*** Now that all of the 22,000 protein-coding human genes have been sequenced, researchers want to know which of these proteins interact with each other. Marc Vidal and colleagues have taken an initial step towards addressing this issue and report their findings in Nature this week. They analysed the interactions between 8,100 proteins and detected 2,800 interactions, revealing more than 300 new connections to over 100 disease-associated proteins. Seventy-eight per cent of the interactions could be verified using a second, different biochemical method. The authors concluded from a literature search that 85 per cent of the identified interactions are novel while comparison with curated databases suggests that 96% of the identified interactions are novel. The study may also yield insight into the way protein interactions change throughout evolution, the authors say. They found that proteins of the same evolutionary level are more likely to interact with each other. For example, human-specific proteins are more likely to interact with each other than with proteins found in all multicellular animals. There is still a long way to go towards establishing a complete interaction database of all human proteins. The study identifies one per cent of the entire human 'interactome,' the authors estimate. CONTACT: Marc Vidal (Dana Farber Cancer Institute, Boston, MA, USA) Tel: +1 617 632 5180; E-mail: marc_vidal@dfci.harvard.edu [12] Microbiology: Corrupting the bacterial quorum (pp750-753) In a process known as quorum sensing, bacteria communicate with each other using chemical signalling molecules called autoinducers. This type of communication allows the microbes to synchronize their behaviour and thus respond as a multicellular organism. One autoinducer, known as AI-2, is a universal molecule that many species of bacteria use to communicate for this purpose. But a paper appearing in Nature this week shows that some species of bacteria can interfere with AI-2-directed communication, thereby hindering other species' ability to respond to the chemical signal. The authors, Karina Xavier and Bonnie Bassler, say that the findings could have implications for human health relating to the maintenance of beneficial microorganisms in the gut and the prevention of bacterial diseases. CONTACT Bonnie Bassler (Princeton University, NJ, USA) Tel: +1 609 258 2857; E-mail: bbassler@molbio.princeton.edu [13] And finally... Quicksand won't suck you right in (p635) Paradoxically, quicksand is easy to sink into but very hard to escape from. Researchers simulating the way this mixture of fine sand, clay and salt water behaves find that quicksand liquefies when perturbed, explaining why it is so easy to sink into. The more it moves, the more liquid it becomes, report Daniel Bonn and his colleagues in a Brief Communication in this week's Nature. This explains why moving too much only makes things worse, because it helps you sink in further. Once the quicksand has liquefied, the sand settles at the bottom, making it so dense that it is impossible for material of the same density as a human to become completely submerged. "Any unfortunate victim should sink halfway into the quicksand," say the authors, "but could then take solace from the knowledge that there would be no risk of being sucked beneath the surface." But this reassurance comes at a price: pulling out a foot takes a force equivalent to that needed to lift a medium-sized car. CONTACT Daniel Bonn (University of Amsterdam, The Netherlands) No telephone number at present - please use the following email address while we try to find a contact phone number: E-mail: bonn@science.uva.nl ALSO IN THIS ISSUE... [14] Isotope-induced partial localization of core electrons in the homonuclear molecule N2 (pp711-715) [15] Trace element signature of subduction-zone fluids, melts and supercritical liquids at 120-180 km depth pp724-727) [16] Ca21/calmodulin is critical for brassinosteroid biosynthesis and plant growth (pp741-745) [17] Phosphatidylserine-dependent engulfment by macrophages of nuclei from erythroid precursor cells (pp754-758) [18] A non-haem iron centre in the transcription factor NorR senses nitric oxide (pp759-763) 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, Tasmania: 6 BELGIUM Liege: 6 Namur: 11 CANADA Ottawa: 14 CHINA Taichung, Taiwan: 4 Taipei, Taiwan: 4 CROATIA Rijeka: 14 FRANCE Gif-sur-Yvette: 6 Meudon: 3 Paris: 3, 6, 9, 13 Plouzane: 6 Toulouse: 6 GERMANY Berlin: 14 Bremerhaven: 6 Dresden: 14 Hamburg: 6 Wuerzburg: 14 ISRAEL Jerusalem: 3, 15 ITALY La Spezia: 10 JAPAN Nagoya: 4 Osaka: 17 Sendai: 14 Tokyo: 4, 17 Tsukuba: 4 Yokohama: 6 MOROCCO Agadir: 9 THE NETHERLANDS Amsterdam: 13 SWEDEN Stockholm: 7 SWITZERLAND Bern: 6 Zurich: 15 UNITED KINGDOM Exeter: 6 Fife: 10 Portaferry: 10 Southampton: 6, 10 Thurso: 10 UNITED STATES OF AMERICA Arizona Tempe: 7 California Los Angeles: 6 Pasadena: 14 Sacramento: 11 San Marcos: 6 Santa Cruz: 3 Colorado Boulder: 6 Georgia Atlanta: 18 Maryland Rockville: 8 Massachusetts Beverly: 11 Boston: 11 Cambridge: 1, 2, 3 Woburn: 11 Woods Hole: 6 Missouri St. Louis: 8 New Jersey Princeton: 6, 12 New York Mahopac: 7 North Carolina Beaufort: 5 Durham: 5 Pennsylvania University Park: 6 Texas Houston: 11 Washington Pullman: 16 Seattle: 6 PRESS CONTACTS... 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 Rinoko Asami, Nature Tokyo Tel: +81 3 3267 8751; E-mail: r.asami@naturejpn.com For the UK/Europe/other countries not listed above Ruth Francis, Nature London Tel: +44 20 7843 4562; E-mail r.francis@nature.com Katharine Mansell, Nature London Tel: +44 20 7843 4658; E-mail: k.mansell@nature.com Nature Publishing Group (NPG) is a division of Macmillan Publishers Ltd, dedicated to serving the academic and professional scientific community. NPG's flagship title, Nature, is the world's most highly-cited weekly multidisciplinary journal and was first published in 1869. Other publications include Nature research journals, Nature Reviews, Nature Clinical Practice, and a range of prestigious academic journals, including society-owned publications. NPG is a global company, with headquarters in London and offices in New York, San Francisco, Washington DC, Boston, Tokyo, Paris, Munich and Basingstoke. For more information, please go to www.nature.com

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