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Summaries of newsworthy papers: European hand-axes close time gap, Traces of devoured galaxies, Tip-offs for tipping points, Enzyme activation conundrum explained, Cool lasers, Designer crystals with DNA, Nitrogen loss in the Arabian Sea and Heart to heart

WWW.NATURE.COM/NATURE This press release is copyright Nature. VOL.461 NO.7260 DATED 03 SEPTEMBER 2009 This press release contains: · Summaries of newsworthy papers: Relics: European hand-axes close time gap Astrophysics: Traces of devoured galaxies Review: Tip-offs for tipping points Opinion: Pakistan’s higher-education reform experiment Molecular biology: Enzyme activation conundrum explained Physics: Cool lasers Chemistry: Designer crystals with DNA Ocean science: Nitrogen loss in the Arabian Sea And finally… Heart to heart · 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. 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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, 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] Relics: European hand-axes close time gap (pp 82-85) A reassessment of two archaeological sites in southern Spain suggests that Europeans were using finely worked hand-axes earlier than previously believed. Work online in Nature this week will redefine the way we think about tool use as they show a longer history of well-developed hand-axe culture in Europe during the Early Pleistocene. A key transition in the history of technology was from the simple chopper-like tools used by the earliest stone-using hominins to the more finely worked, bifacial artefacts known as hand-axes. Researchers have been puzzled by the apparent million year time lag between the appearance of these more sophisticated tools in Asia and the earliest records of them in Europe. Gary R. Scott and Luis Gibert reassess the dating of two hand-axe-bearing sites in southern Spain and suggest that they are 0.76 and 0.9 million years old, significantly closing the time gap. CONTACT Luis Gibert (Berkeley Geochronology Center, Berkeley, California, USA) Tel: + 34 616 076 485 or: +34 661 250 087; Email: gbeotas@hotmail.com Gary R. Scott (Berkeley Geochronology Center, Berkeley, CA, USA) Tel: +1 510 644 9200; or: +1 510 3266093; Email: gscott@bgc.org [2] Astrophysics: Traces of devoured galaxies (pp 66-69; N&V) Our Galaxy’s nearest neighbours, the Andromeda and Triangulum galaxies, have been mapped with unprecedented sensivity, revealing many previously unseen stars and structures. The results, reported in this week’s Nature, provide a picture of the galaxies’ shared history that confirms the important role of gravitational interactions and accretion in the growth of large galaxies. A popular model of galaxy evolution holds that galaxies grow through the accretion of smaller galaxies — a kind of galactic cannibalism. This ‘hierarchical model’ predicts that galaxies such as Andromeda should be surrounded by relics of the devoured galaxies: loosely bound stars at distances up to a hundred times the radius of the large galaxy’s central disk. Alan McConnachie and colleagues have used the Canada–France–Hawaii telescope to probe the faint outer reaches of Andromeda and its largest satellite galaxy, Triangulum. They find stars and coherent structures that are almost certainly remnants of dwarf galaxies pulled apart by the gravitational field of Andromeda. The authors also find evidence for a past close encounter of Triangulum with Andromeda — an encounter that pulled millions of stars away from Triangulum, and also perturbed Andromeda’s disk. (See the paper’s Supplementary Information for a movie showing how this might have happened.) In this way, Triangulum itself may have fed its larger neighbour. CONTACT Alan McConnachie (NRC Herzberg Institute of Astrophysics, Victoria, British Columbia, Canada) Tel: +1 250 363 0070; Email: alan.mcconnachie@nrc-cnrc.gc.ca Nickolay Gnedin (University of Chicago, Chicago, IL, USA) N&V author Tel: +1 773 834 4388; Email: gnedin@fnal.gov [3] Review: Tip-offs for tipping points (pp 58-59) Predicting critical tipping points before they are reached is tough, but research is starting to suggest the existence of generic early-warning signals that could apply to a range of systems from the economy to the climate. Marten Scheffer and colleagues review the work optimistically in Nature this week. Many complex systems, ranging from ecosystems to financial markets and the climate, can have critical thresholds or tipping points at which a sudden shift from one stable state to a contrasting regime may occur. The researchers suggest that in situations where the existence of a critical transition is suspected, the generic character of the warning signs suggests that they may provide valuable information on whether the probability of a major event is increasing. CONTACT Marten Scheffer (Wageningen University, Wageningen, Netherlands) Tel: +31 317 484039; Email: Marten.Scheffer@wur.nl Opinion: Pakistan’s higher-education reform experiment (pp 38-39) After decades of neglect, Pakistan set out in 2002 to dramatically reform its higher-education system. Although it is too early to judge the final outcome of the experiment, the successes and failures of reform initiatives hold lessons for other nations, say five international authors in this week’s Nature Opinion section. The problems with Pakistan’s higher-education system were documented in 2001 by a task force set up by General Pervez Musharraf’s military government. Chronic underfunding and low enrolment beset the system. Only 2.6% of Pakistan’s 17–23 year olds attended an institution of higher education, compared with 6.2% in India and 12.7% in Iran. Total public funding for 41 public-sector universities was merely 0.1% of the country’s gross domestic product. Some of this neglect was understandable — for decades the international donor and development communities had focused attention on primary education at the expense of higher education. Major investments in universities and in the scientific workforce since 2002 mean that Pakistan can point to concrete changes. The highs include more research papers, more PhDs and greater visibility for Pakistani research. The lows include an absence of external evaluation, and an excessive centralization of the reform effort that led to divisions among faculty. At times, the speed and scale of reform outpaced the ability of Pakistan’s universities to adapt, say the authors. The authors argue that greater participation, transparency and accountability may have increased the credibility and support for reform. CONTACT Athar Osama (Visiting Fellow, Boston University, MA, USA) Tel: +44 7711 198092, E-mail: athar.osama@Gmail.com [4] Molecular biology: Enzyme activation conundrum explained (AOP) DOI: 10.1038/nature08314 ***This paper will be published electronically on Nature's website on 02 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 03 September, but at a later date. *** A long-standing conundrum about how the cellular enzyme RAF is activated is laid to rest in this week’s Nature. The finding may have implications for anti-cancer drug design. The RAF family of kinases regulates various cellular processes including cell growth, differentiation and survival. Mutations in the gene can trigger cancer. Frank Sicheri and colleagues explain how the RAF enzyme’s catalytic function is controlled — for the enzyme to be active, the kinase domain of the molecule adopts a newly discovered side-to-side dimer configuration. CONTACT Frank Sicheri (Mount Sinai Hospital, Toronto, Ontario, Canada) Tel: +1 416 586 8471; Email: sicheri@lunenfeld.ca [5] Physics: Cool lasers (pp 70-73) A novel laser cooling mechanism could boost studies of supercooling and yield applications in optical refrigeration. In this week's Nature, Ulrich Vogl and Martin Weitz demonstrate laser cooling of an atomic gas by means of collisional redistribution of radiation — radiation from a laser causes dense, frequently colliding rubidium atoms to bind gently together only to break apart again, slowing and cooling the atoms down. It's thought the technique could be used to lower the temperature at which gases become ‘supercooled’, enabling them to remain gaseous at temperatures well below their conventional freezing point. This in turn could shed light on possible new states of matter. CONTACT Martin Weitz (Universität Bonn, Bonn, Germany) Tel: +49 228 73 4837; Email: Martin.Weitz@uni-bonn.de [6] Chemistry: Designer crystals with DNA (pp 74-77) Building three-dimensional (3D) macroscopic objects where the position of every constituent atom can be controlled at will has proved difficult, until now. A new method, described in this week’s Nature, sees researchers design and self-assemble well-ordered 3D crystals with precise control. It’s thought that the technique could find use in structural biology and in the organization of nanoelectronics. The method, devised by Nadrian Seeman and colleagues, gives researchers microscopic control over the atoms in macromolecules, and hence the structure of 3D crystals. They use robust DNA structures, called tensegrity triangles, with sticky ends that pair up in a complementary fashion to form a periodic structure. The approach yields crystals of around 200 micrometres in size, in which the positions of the atoms can be determined with a precision of 4 angstrom. CONTACT Nadrian Seeman (University of New York, New York, USA) Tel: +1 212 998 8395; Email: ned.seeman@nyu.edu [7] Ocean science: Nitrogen loss in the Arabian Sea (pp 78-81) In Nature this week, scientists reassess the pathway of nitrogen loss in the Arabian Sea, revealing that denitrification is the dominant process occurring. The global inventory of fixed nitrogen may be out of balance, with losses exceeding inputs. Much of this loss occurs in low oxygen environments, known as oxygen minimum zones, with nitrogen loss occurring via two major processes: denitrification, where oxygen is removed from nitrogen compounds by organic matter; and anammox, where ammonia is removed anaerobically. Recently it has been suggested that anammox alone may be responsible for fixed nitrogen loss in oceanic oxygen minimum zones, where about 35% of oceanic nitrogen is produced. Bess Ward and colleagues now find that denitrification rather than anammox dominates the nitrogen loss term in the Arabian Sea, the largest and most intense oxygen minimum zone in the world. They suggest that the conventional nitrogen cycle of the Arabian Sea must be revised to include the anammox process, but denitrification is the dominant flux for fixed nitrogen loss in this oxygen minimum zone. CONTACT Bess Ward (Princeton University, Princeton, New Jersey, USA) Tel: +1 609 258 5150; Email: bbw@princeton.edu [8] And finally… Heart to heart (pp 95 - 98) A new embryological study of a lizard and a turtle shows that the division of an ancestral single ventricle into two chambers is related to the expression of a transcription factor called Tbx5. The work, published in Nature this week, suggests that altered Tbx5 expression may be an evolutionary force driving embryonic heart patterning, providing the key adaptation to high-energy terrestrial life: a heart with separate cavities. Birds, mammals and crocodiles have hearts with two separate ventricles, servicing separate pulmonary and systemic circulations. Amphibians have just one ventricle, but in most reptiles, the situation is unclear. In embryonic birds and mammals, Tbx5 expression is restricted to precursors of the left ventricle. Bruneau and colleagues show that in turtles and lizards it is initially expressed throughout the ventricle, but in turtles (although not lizards) it is later restricted to the left side of the chamber. They used mouse genetic analysis where they misexpressed or reduced the levels of Tbx5 to confirm that Tbx expression patterns markedly affect chamber formation. CONTACT Benoit Bruneau (J. David Gladstone Institutes, San Francisco, CA, USA) Tel: +1 415 734 2708; Email: bbruneau@gladstone.ucsf.edu ADVANCE ONLINE PUBLICATION ***These papers will be published electronically on Nature's website on 02 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 them on this release to avoid multiple mailings they will not appear in print on 03 September, but at a later date. *** [9] Response and Resistance to MEK Inhibition in Leukaemias Initiated by Hyperactive Ras DOI: 10.1038/nature08279 [10] Reactive Oxygen Species prime Drosophila haematopoietic progenitors for differentiation DOI: 10.1038/nature08313 [11] AOF1/KDM1A is a histone demethylase required to establish maternal genomic imprints DOI: 10.1038/nature08315 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 Sydney: 2 CANADA: Hamilton: 2 Montreal: 4 Ontario: 2, 8 Ottawa: 8 Toronto: 2, 4, 8 Vancouver: 2 Victoria: 3, 2 CHINA Shanghai: 11 FRANCE Paris: 2 Strasbourg: 2 GERMANY Bonn: 5 Hamburg: 3 Heidelberg: 2 Potsdam: 3 INDIA Goa: 7 JAPAN Yokohama: 8 NETHERLANDS Utrecht: 3 Wageningen: 3 SPAIN Seville: 3 UNITED KINGDOM Cambridge: 2 Edinburgh: 2 Leicester: 2 UNITED STATES OF AMERICA California Berkeley: 1 Los Angeles: 2, 10 San Diego: 3 San Francisco: 8, 9 Illinois Argonne: 6 Indiana West Lafayette: 6 Maryland Bethesda: 9 Frederick: 9 Massachusetts Amherst: 2 Boston: 10, 11 Cambridge: 11 Michigan East Lansing: 8 New Jersey Princeton: 7 New York New York: 6 Pennsylvania Millersville: 8 Swarthmore: 8 University Park: Rhode Island Providence: 7 Texas Dallas: 8, 9 Washington Seattle: 7 Wisconsin Madison: 3 PRESS CONTACTS… For North America and Canada Neda Afsarmanesh, Nature New York Tel: +1 212 726 9231; E-mail: k.mcgoldrick@naturedc.com For Japan, Korea, China, Singapore and Taiwan Mika Nakano, Nature Tokyo Tel: +81 3 3267 8751; E-mail: m.nakano@natureasia.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 About Nature Publishing Group (NPG): Nature Publishing Group (NPG) is a publisher of high impact scientific and medical information in print and online. NPG publishes journals, online databases and services across the life, physical, chemical and applied sciences and clinical medicine. Focusing on the needs of scientists, Nature (founded in 1869) is the leading weekly, international scientific journal. In addition, for this audience, NPG publishes a range of Nature research journals and Nature Reviews journals, plus a range of prestigious academic journals including society-owned publications. Online, nature.com provides over 5 million visitors per month with access to NPG publications and online databases and services, including Nature News and NatureJobs plus access to Nature Network and Nature Education’s Scitable.com. Scientific American is at the heart of NPG’s newly-formed consumer media division, meeting the needs of the general public. Founded in 1845, Scientific American is the oldest continuously published magazine in the US and the leading authoritative publication for science in the general media. 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