A method to regrow teeth
Scientists have for the first time successfully replaced natural teeth in mice with teeth that were created in a Petri dish from single cells. Takashi Tsuji and colleagues started with the two cell types that develop into a tooth –mesenchymal and epithelial cells. First they grew each cell type separately to get larger quantities of cells and then injected them into a drop of collagen – a substance which ‘glues’ cells together in an organism. The cells developed into a budding tooth with high efficiency, and when transplanted into the cavity of an extracted tooth in a mouse developed normally and showed the same composition and structure as natural teeth.The authors provide further evidence that this method can be applied to any organ that develops from these cell types by regrowing a follicle that eventually forms a whisker in a mouse.
Author contact:Takashi Tsuji (Tokyo University of Science, Chiba, Japan)Tel: +81 4 7122 9711; E-mail: t-tsuji@nifty.com

Behaviour of Western Scrub-Jays
Western scrub-jays can save for the future. These prudent members of the corvid family can spontaneously plan for tomorrow without reference to their current motivational state.Nicola Clayton and colleagues studied the behaviour of western scrub-jays under different feeding conditions. The birds first experienced ‘training’ during which they were placed in two different compartments on alternate mornings for six days. In one compartment they were always given breakfast and in the other they were not. After training the birds were unexpectedly given food in the evening. The authors report that the birds stored more of this evening food when in the compartment in which they had not been given breakfast - as they would expect to be hungry again the next morning - relative to the one in which they had.In a similar experiment, the birds also differentially stored a particular food in the compartment in which that type of food would not be available the next morning, demonstrating future planning and ensuring a choice of food the following breakfast. Such forward planning challenges the belief, still held by many, that making provision for the future is a uniquely human skill.
CONTACT-Nicola Clayton (University of Cambridge, UK)Tel: +44 1223 333 559; E-mail: nsc22@cam.ac.uk Sara J. Shettleworth (University of Toronto, Canada) N&V authorTel: +1 416 978 5201; E-mail: shettle@psych.utoronto.ca

Chemistry: Halogen soup
Chemists have developed a simple method for making testosterone-like molecules containing halogen atoms. Halogenated natural products have been isolated from marine organisms and are often biologically active, so it's hoped the methodology will boost the development of novel therapeutics.Kazuaki Ishihara and his colleagues mixed a simple halogen-containing 'donor’, a compound that contained phosphorus, and a small-molecule scaffold and thus isolated complex products containing halogen atoms. The reaction is selective for a specific product, giving the manufacturer a high degree of control over the three-dimensional structure of the end products.The simple manufacturing process, described in this week's issue of Nature, uses simple ingredients to form complicated molecules and may enable chemists and biochemists to understand how similar halogenated natural products are made in nature.
CONTACT-Kazuaki Ishihara (Nagoya University, Japan)Tel: +81 52 789 3331; E-mail: ishihara@cc.nagoya-u.ac.jp Phil S. Baran (Scripps Research Institute, La Jolla, CA, USA) N&V authorTel: +1 858 784 7373; E-mail: pbaran@scripps.edu

Glaciology: Subglacial lakes discovered in East Antarctica
Scientists identify large, subglacial lakes in East Antarctica, which are situated at the start of fast-flowing ice streams. The lakes cover an area similar to that of Lake Vostok - the largest of more than 140 lakes already discovered - and could be contributing significantly to the dynamics of the overlying ice sheet.Ice streams are large ‘rivers’ of fast-flowing ice within continental ice sheets that transport inland ice towards the sea. Previous studies have revealed several large bodies of water trapped under the East Antarctic ice sheet but, until now, all the lakes discovered in this region have been self-contained and isolated from the onset of rapid ice flow.Michael Studinger and colleagues used satellite radar imagery and ice-surface elevations to reveal four, flat, featureless regions of ice surface surrounded by troughs and ridges - typical ice surface morphology of subglacial lakes. The lakes are located right at the onset of the Recovery Glacier ice stream in East Antarctica and are apparently linked to rapid ice flow across a 280-km-wide region, adding 35 thousand million tons of ice per year into the sea. The authors suggest that these lakes should be taken into account when predicting the fate of ice sheets with the changing climate of the world.
CONTACT-Michael Studinger (Columbia University, Palisades, NY, USA)Tel: +1 845 365 8598; E-mail: mstuding@ldeo.columbia.edu
The following co-author may also be available:Robin E. Bell (Columbia University, Palisades, NY, USA)E-mail: robinb@ldeo.columbia.edu Jack Kohler (Norwegian Polar Institute, Tromso, Norway) N&V authorTel: +47 77 75 06 55; E-mail: jack.kohler@npolar.no

Honey, I Shrunk Oble!
The National Institute of Physics, University of the Philippines (UP) has miniaturized the Oblation (UP’s trademark) as part of its project on micro-fabrication of functional micro-devices using non-linear multi-photon absorption. The research project aims to use micro-structures as components in an integrated miniaturized laboratory.
The University of the Philippines’ National Institute of Physics (NIP) through its Instrumentation Physics Laboratory has figured out how to miniaturize the Oblation (University of the Philippines’ trademark) using femtosecond-pulse near-infrared laser. The light-sculptured three-dimensional microscopic Oblation measures around 20 micrometers in length and 10 micrometers in width. The miniaturization of the Oblation is part of Wavefront Engineering Team’s (WET) research project on micro-fabrication of functional micro-devices using non-linear multi-photon absorption. The research intends to fabricate structures in the micrometer scale with the final aim of using the micro-structures as components in an integrated miniaturized laboratory or a micro-machine functioning under a microscope.The WET is headed by Dr. Vincent Ricardo Daria, Associate Professor at NIP, and is composed of researchers and students, namely: Dr. Darwin Palima (Adjunct Professor), Godofredo Bautista (Ph.D Physics student), Anthony Montecillo (MS Material Science and Engineering student), Jacqueline Romero (MS Physics student), Andrew Banas (BS Physics student), Atchong Hilario (BS Applied Physics student) and Reniel Cabral (BS Applied Physics student). Joaquin Jose Escay who graduated BS Applied Physics in March 2006 also did significant programming work for the project.The micro-oblation is a solid plastic formed by light, which is used to chisel the sculpture. According to Dr. Daria, the miniaturization of the Oblation is a way to test the resolution of their micro-fabrication system. When asked why they chose to miniaturize UP’s trademark, Daria said “pag-paliit ng oble nagpapatunay na gawa natin ito dito sa UP” (fabrication of the micro-oblation demonstrates that this micro-structure was built here in UP.) WET’s goal is to use light-sculptured devices as components in a miniaturized micro-laboratory. After the fabrication process, the micro-components can also be actuated by light. Light is a form of energy and therefore has momentum. When the momentum of light is transferred to the light-sculptured micro-components, these components will move and become a part of a micro-machine. Hence, using these miniaturized components, WET will make micro-machines fabricated and controlled by light. The miniaturization and fabrication of components is just an intermediate step in building a scientific breakthrough. The research is expected to produce a scientific tool to be used by biologists and chemists. This tool would help the scientists have a more controlled environment in conducting experiments. According to Dr. Daria, most of the experiments are done in bulk or in macro-scale and so data gathering and analysis is usually achieved via statistical methods. In doing the experiment using a smaller (microscopic) scale, the interactions and chemical reactions would be more localized and can aid in major scientific breakthroughs.WET is now in the stage of testing and fabricating components. In the long run, the researchers want to have these components compiled in their system and eventually create micro-machines. The research project is funded by the Department of Science and Technology-Philippine Council for Advanced Science and Technology, Research and Development (DOST-PCASTARD). Dr. Daria also received a grant amounting to P 2.3M from DOST-Institutional Development Program for setting up a system for programmable phase using a spatial light modulator – an essential component of the project that can also be used for other research ventures. UP provided the femtosecond-pulse Titanium: Sapphire laser, which is the near-infrared light source for micro-fabrication.
Associated links
http://www.ovcrd.upd.edu.ph

Rust diseases – a threat to global food security
Next week, some of Australia’s and the world’s foremost experts in the field of rust diseases will be in Sydney to attend a symposium on the topic – “Rust Diseases: Threats to Global Food Security in the Context of Climate Change.”
Rust diseases – a threat to global food securityChronic food shortages caused by cereal rusts have happened in the past – and today international agricultural agencies are on the alert again because of a new threat in Eastern Africa, a rust known as Ug99.A virulent disease of wheat, Ug99 has the potential to wipe out a quarter of the world’s wheat crop.Next week, some of Australia’s and the world’s foremost experts in the field of rust diseases will be in Sydney to attend a symposium on the topic – “Rust Diseases: Threats to Global Food Security in the Context of Climate Change.”The symposium has been organised by the NSW Centre for Plant and Animal Biosecurity, an alliance between the NSW Department of Primary Industries and the University of Sydney.High on the agenda is the threat to global food security from Ug99, which last month was reported to have jumped from eastern Africa and is now infecting wheat in Yemen in the Arabian Peninsula.Countries in the predicted pathway of Ug99 grow more than 65 million hectares of wheat a year.NSW Department of Primary Industries (DPI) Principal Research Scientist, Dr Colin Wellings said: “There is international concern that this new stem rust could destroy vast quantities of wheat and threaten food security at a time that world wheat stocks are at a historic low.“The potential for the disease to move into Central Asia is enormous and alarming.”Speakers at the symposium include the facilitator of the Global Rust Initiative (GRI), Dr Richard Ward, who is based at the international plant breeding centre CIMMYT in Mexico.GRI was set up in 2005 in response to recurring epidemics of Ug99 in Kenya and Ethiopia. (In the early 1950s, a major stem rust epidemic in North America destroyed up to 40 percent of that continent’s spring wheat crop.)Dr Ward says that “the potential for a serious international epidemic of stem rust based on Ug99 has galvanized considerable global concern to secure wheat yield protection through breeding for rust resistance.”In NSW, wheat growers are on alert because of the discovery of a new stripe rust which disarms a resistance gene that has been bred into some popular varieties of wheat.Dr Wellings believes that growers have two to three years before the new stripe rust becomes problematic for wheat varieties carrying the Yr17 resistance gene.“If this proves to be the case, then there should be time for farmers to change the varieties they are planting.”Dr Wellings said that for nearly a century, DPI and University of Sydney scientists have been working to find new genes which confer resistance and breed them into Australian cereal varieties.He said that in 1973 a stem rust outbreak caused “historic and massive losses” in crops in northern NSW and Queensland. This galvanised government and industry to take a national approach to work towards being prepared for new incursions.
The Cooperative Research Centre (CRC) for National Plant Biosecurity is a major sponsor of the symposium.Speakers at the symposium include:Mr Terry Enright, Chairman, Grains Research and Development CorporationProf John Lovett, Chairman, CRC for National Plant BiosecurityDr Sanjaya Rajaram, ICARDA-CIMMYT, SyriaDr Les Szabo, US Department of Agriculture Dr Rick Ward, Global Rust InitiativeProfessor Robert Park and Dr Harbans Bariana, University of SydneyThe symposium is being held on 21 and 22 February at the Elizabeth Macarthur Agricultural Institute at Menangle, in Sydney’s south-west. The program is at: http://www.agric.usyd.edu.au/news/index.shtml

Fruit flies identified from DNA ‘signature’
A discovery that enables the most economically important fruit fly species to be identified from their DNA ‘signature’ could avert future devastating fruit fly outbreaks, according to scientists from the NSW Department of Primary Industries (DPI).
A discovery that enables the most economically important fruit fly species to be identified from their DNA ‘signature’ could avert future devastating fruit fly outbreaks, according to scientists from the NSW Department of Primary Industries (DPI). Molecular biologists and entomologists from DPI have developed the means to identify selected species of fruit fly from segments of their DNA. This enables fruit fly to be developed from larvae or incomplete adultsMolecular biologist Dr Deb Hailstones said the discovery greatly increased the likelihood of an outbreak of fruit fly being contained early. “Previously, fruit fly species could only be identified accurately visually from mature adults. This meant there could be a delay of weeks before an accurate assessment can be made of a species, and whether it is an economic threat.The new method of identification relies on use of a molecular key development by DPI entomologist, Peter Gillespie. Dr Hailstones said the key sets out a means for amplifying and comparing target sections of DNA that the different species of fruit fly have in common.“It is not yet able to distinguish between the hundreds of species of fruit flies known to damage fruits and vegetables. However we can identify patterns of DNA that are typical of the 30 species of greatest significance for Australian horticulture.”The technique enables this group of economically important species to be identified from larvae or from incomplete adults.Older methods require fruit flies to be identified morphologically, from their physical characteristics, which means that specimens of adult flies have to be supplied – and they have to be complete. Dr Hailstones said the molecular key will be useful for border surveillance and quarantine and for the problem specimens where eggs or early maggots are found in produce.“Instead of fruit rotting at borders or in quarantine while scientists wait until visual tests can be done, the insects can be identified from their DNA almost immediately”, she said.The key has been proposed as an Australian standard and will be updated as soon as new discoveries are made.Fruit flies are amongst the world’s most destructive horticultural pests and a major outbreak can cost many millions of dollars. In 1995 in north Queensland, an outbreak of papaya fruit fly cost industry an estimated $100 million. The research was undertaken by staff from the Agricultural Scientific Collections Unit in Orange and the Elizabeth Macarthur Agricultural Institute.
Contact: Dr Deborah Hailstones on 4640 6442

Scientists identify wheat germplasm suitable for acid soils
NSW Department of Primary Industries (DPI) scientists have identified a major new source of wheat germplasm tolerant of aluminium toxicity, paving the way for the breeding of new bread wheat varieties able to grow in acid soils.
31 January 2007Scientists from DPI in Wagga Wagga and Tamworth screened hundreds of ancient landrace wheats collected from around the world as part of a research effort to find aluminium (Al) tolerant bread wheats. Landraces are the ancestors of modern wheat cultivars. Most sources of Al tolerance in Australian wheat can be traced back to Brazil or China, and according to DPI molecular biologist Dr Harsh Raman, the new genetic material found appears to be different from that used in current breeding programs.An initial laboratory study of 250 landraces found 35 were Al tolerant. After a root tip stain was applied, root regrowth was measured and 33 of these were found to increase their root length after exposure to Al.The tolerant landraces come from eight countries - Bulgaria, Croatia, India, Italy, Nepal, Spain, Tunisia and Turkey – and Dr Raman said that subsequent molecular analysis indicated that they are from diverse genetic backgrounds.“Conventional breeding has reduced the available gene pool of wheat, possibly reducing the availability of useful or novel genes adapted to stress such as that induced by aluminium.”Landraces have already proved a valuable source of important genes, such as those conferring reduced height used extensively in Australian wheat breeding programs.Dr Raman said the new landraces could be used to expand the genetic base currently available and may also hold other important genes.“Given that there is mostly more than one stress factor placed on a plant at any one time, the possibility exists that landraces that are adapted to one stress may carry useful adaptations to other stresses such as salinity, nutrient deficiencies and foliar and root diseases.”Acid soils are one of Australian farming’s worst environmental problems.About 70 percent of Australian soils are associated with extremes in pH. Low pH releases aluminium at levels which are toxic to many crop species, constraining root growth and uptake of water and nutrients. In NSW, acid soils are estimated to cause losses of up to $400 million dollars each year. The landrace germplasm examined for this research came from the Australian Winter Cereals Collection, located at Tamworth. Initial findings were reported in the international journal Genetic Resources and Crop Evolution. The research was funded under the NSW Government’s Biofirst strategy. Media inquiries: Joanne Finlay on 6391 3171 or 0428 491 813.

Immunology: HIV reveals vulnerable side
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.CONTACTPeter D. Kwong (National Institute of Allergy and Infectious Diseases, NIH, Bethesda, MD, USA)Tel: +1 301 594 8685; E-mail: pdkwong@nih.gov

Sleep deprivation impairs subsequent learning
Sleep deprivation may impair memory for subsequent experiences by altering the function of the hippocampus, reports a paper in the March issue of Nature Neuroscience. Previous research has shown that sleep occurring after an experience can be critical to learning and memory but this new study shows why sleep before an experience is also critical, and that memory systems do not function normally without it.Matthew Walker and colleagues deprived people of a night’s sleep and then asked them to observe and remember a large set of picture slides for a subsequent recognition test. Brain activity was monitored with fMRI – functional magnetic resonance imaging – while subjects viewed the slides. Following a full night of sleep, the subjects were then queried about the slides on the next day. The researchers found that sleep-deprived subjects showed decreased activity in the hippocampus – a brain region important for memory – relative to control subjects who were not sleep-deprived while viewing the pictures; sleep-deprived people also had poorer subsequent recall abilities. The relationship of activation in other brain areas to activation in the hippocampus was also altered, suggesting that sleep deprivation alters memory-encoding strategies.
Author contact:
Matthew Walker (Harvard Medical School, Boston, MA, USA)Tel: +1 617 731 6378; E-mail: mwalker@hms.harvard.edu

In utero protein regulation
A novel strategy for regulating a protein important in development is described online in Nature this week. Michael T. Longaker and colleagues report that, in mice, glycogen synthase kinase-3beta (GSK-3beta) can be artificially controlled from within the mother's uterus, in a reversible and time-controlled manner.GSK-3beta plays an integral part in a variety of biological processes, although its specific developmental roles remain unclear. In the present study the authors used an existing chemically regulated form of the GSK-3beta gene, whereby expression of the GSK-3beta protein is controlled by the presence or absence of the drug rapamycin. Using this approach combined with conventional mutant analysis they defined a specific requirement for GSK-3beta in midline development: mice that did not express the protein had cleft palate, incomplete fusion of the ribs and a split sternum.In addition, the authors were able to rescue some of the developmental defects using maternal rapamycin treatment to restore internal GSK-3beta activity during two distinct windows of gestation. They propose that their studies provide an improved method for defining the timing and level of protein expression during development, a detailed knowledge of which is essential for rescuing developmental defects.Author contact:Michael T. Longaker (Stanford University Medical Center, CA, USA)Tel: +1 650 736 1707; E-mail: longaker@stanford.edu

Viral highways: spreading from cell to cell
A number of retroviruses, including HIV, induce cells to form long bridges along which the virus particles move from infected cells to uninfected cells, according to a paper in the March issue of Nature Cell Biology.Viral transmission has long been recognized to be more efficient between infected and target cells that are in direct contact with each other. Exactly how viruses move from one cell to another is unclear, although structures called virological synapses, which contain the virus particle and form between areas of cell–cell contact, are thought to be important in this process. In the present study Walther Mothes and colleagues describe a novel mode of cell–cell transmission for three retroviruses – murine leukaemic virus, human immunodeficiency virus and avian leucosis virus – along the outside of long, thin intercellular bridges. These bridges seem to be stabilized by an association between a viral protein expressed by the infected cell and a viral-receptor protein in the target cell. Mutants of these proteins that cannot interact destabilize the bridges and markedly reduce viral spreading from cell to cell. This mode of transmission is observed in a variety of different cells, suggesting that it may be a general mechanism of viral spreading.Whether these intercellular viral highways represent a predominant mode of viral transmission, their relative importance for different viruses, and their relationship to virological synapses are open questions. However, interference with the bridge structures described by Mothes and colleagues may provide a new avenue to limit the infectivity of a number of key viral diseases.
Author contact:
Walter Mothes (Yale School of Medicine, New Haven, CT, USA)Tel: +1 203 737 2203; E-mail: walter.mothes@yale.edu

Human adult stem cells can regenerate muscle
Human adult stem cells isolated from human adult blood vessels are able to regenerate muscle in a mouse model of muscular dystrophy, according to a study published online this week in Nature Cell Biology.The lure of a cure for muscle-wasting diseases has lead researchers to explore the regeneration potential of stem cells isolated from the walls of blood vessels. In a recent Nature paper Giulio Cossu and colleagues showed that such cells isolated from young golden retrievers regenerated the muscles of dystrophic dogs when injected into their circulation. A new study by the same team demonstrates that cells with similar properties can be isolated from human juvenile and adult blood vessels.The same researchers isolated this type of stem cell from juvenile dystrophic patients and grew them in cell culture. Muscular dystrophy is linked to a mutation in dystrophin, a gene required for muscle formation, and the authors genetically modified the stem cells to make them express the corrected version of the gene. After injection into the blood vessels of dystrophic mice, these cells found their way to skeletal muscle, which they were able to partly regenerate. Importantly, the cells were shown to reconstitute the muscle’s own stem cell population. The authors suggest that the isolation of these stem cells raises hope for treating muscular dystrophy using the patient’s own cells.
Author contact:
Giulio Cossu (Stem Cell Research Institute, Rome, Italy)Tel: +39 02 2643 4954; E-mail: cossu.giulio@hsr.it

Human adult stem cells can regenerate muscle
Human adult stem cells isolated from human adult blood vessels are able to regenerate muscle in a mouse model of muscular dystrophy, according to a study published online this week in Nature Cell Biology.The lure of a cure for muscle-wasting diseases has lead researchers to explore the regeneration potential of stem cells isolated from the walls of blood vessels. In a recent Nature paper Giulio Cossu and colleagues showed that such cells isolated from young golden retrievers regenerated the muscles of dystrophic dogs when injected into their circulation. A new study by the same team demonstrates that cells with similar properties can be isolated from human juvenile and adult blood vessels.The same researchers isolated this type of stem cell from juvenile dystrophic patients and grew them in cell culture. Muscular dystrophy is linked to a mutation in dystrophin, a gene required for muscle formation, and the authors genetically modified the stem cells to make them express the corrected version of the gene. After injection into the blood vessels of dystrophic mice, these cells found their way to skeletal muscle, which they were able to partly regenerate. Importantly, the cells were shown to reconstitute the muscle’s own stem cell population. The authors suggest that the isolation of these stem cells raises hope for treating muscular dystrophy using the patient’s own cells.
Author contact:
Giulio Cossu (Stem Cell Research Institute, Rome, Italy)Tel: +39 02 2643 4954; E-mail: cossu.giulio@hsr.it

Common genetic variant protects against breast cancer
Scientists have confirmed that a common genetic variant – CASP8 – offers modest protection against breast cancer, according to a study to be published online this week in Nature Genetics. The report provides some of the strongest evidence so far that common variants affect the risk of developing breast cancer, and the size of the collaboration sets an important precedent for future studies.Rare mutations in the genes BRCA1 and BRCA2 significantly raise an individual’s risk of breast cancer, but account for only a fraction of the overall variation in genetic risk. More common variants that have a smaller effect on individual risk have been difficult to find, largely due to the size of the studies needed to identify variants of small effect in a convincing manner.The Breast Cancer Association Consortium, which comprises more than 20 collaborating research groups, examined 9 previously reported breast cancer susceptibility variants in at least 10,000 affected women and 10,000 disease-free women in a study led by Angela Cox. For 8 of the 9 genes, the Consortium reported either no association with breast cancer risk, or marginal evidence for an association. For a variant in the gene CASP8, however, they found a significant association. The particular variant assessed in the study is found in approximately 13% of women of European descent, and is protective, lowering the risk of breast cancer by approximately 10%.
Author contact:
Angela Cox (Sheffield University Medical School, UK)Tel: +44 1142712373; E-mail: a.cox@shef.ac.uk

Large-scale survey of mutations in cancer
One of the largest surveys of mutations in human cancers is reported online this week in Nature Genetics. The study provides a preview of results that may be generated by even larger projects such as The Cancer Genome Atlas, set to begin soon.Previous attempts at cataloguing mutations in different types of cancer have relied on DNA sequencing, which can be too expensive when applied to a large number of tumors. Levi Garraway and colleagues applied a previously developed technique called mass spectrometric genotyping to identify the frequency and distribution of 238 known mutations in 17 oncogenes in 1,000 tumors. The genotyping approach is more sensitive than the sequencing approach, identifying more mutations, and simultaneously detects mutations in multiple oncogenes in a cost-effective manner.The authors report that mutations in three of the oncogenes were not found in any of the tumors, while mutations in the other genes were observed in only 30% of the tumors, indicating that many cancer-causing events remain to be discovered. There were relatively few examples where a specific mutation was found more than once, suggesting that mutations occurring at high frequency will be uncommon.
Author contact:
Levi Garraway (Dana-Farber Cancer Institute, Boston, MA, USA)Tel: +1 617 632 6689; E-mail: levi_garraway@dfci.harvard.edu

Genetic indicators of type 2 diabetes risk
Geneticists have identified five different areas of DNA base-pair change that contribute significantly towards the risk of developing type 2 diabetes mellitus. The finding helps tease apart the complex mix of genetic and environmental factors that contribute to the disease, and may guide the direction of future therapeutics.Constantin Polychronakos and colleagues used high-density arrays to look for the occurrence of over 390,000 single nucleotide polymorphisms (SNPs) - particular regions of DNA containing a single base-pair change - in the genomes of over 2,000 patients with type 2 diabetes and more than 2,000 controls. They identified four different SNP-containing regions that conferred a significant risk to developing the disease, and confirmed an already known association between the TCF7L2 gene and type 2 diabetes. These five genetic regions together might account for 70% of the genetic risk, the authors say.The important variants occur in genes related to the control of insulin secretion and pancreatic development. One gene encodes a protein that helps move zinc ions around and is found solely in the secretory vesicles of beta-cells, which make and release insulin. The finding, published online by Nature this week, has possible dietary implications and hints that therapies targeting zinc may be worth a shot.
Author contact:
Constantin Polychronakos (McGill University, Montreal, Quebec Canada)Tel: +1 514 934 4315; E-mail: constantin.polychronakos@mcgill.caNelson B. Freimer (UCLA, Los Angeles, CA, USA)Tel: +1 310 794 9571; E-mail: nfreimer@mednet.ucla.edu (N&V author)