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Nature press release for 24 May issue

May 25, 2001

PUBLISHING: THE NATURE YEARBOOK OF SCIENCE AND TECHNOLOGY 2001
Authoritative, accessible and totally unique, the new Nature Yearbook is the one-stop desk reference that the scientific world has been waiting for. Containing specially commissioned articles, facts, figures, and an exhaustive country-by-country guide to science and technology world wide, it is essential for anyone requiring accurate, current and comprehensive facts on the major players and trends in the fast moving world of science.
In this weeks issue of Nature, Declan Butler, editor of the Yearbook and European Correspondent of Nature, introduces this exciting new reference title.
        To receive a full press release and a review copy, or to place an order, please contact Suzanne Kidd tel +44 20 7843 4609, email s.kidd@nature.com.

[411494] LIFELINES: SMALL RNAs HIT THE BIG TIME (pp494-498; N&V)
A new way to silence human genes reported in this week’s Nature should prove a powerful tool to investigate gene function.
        In the past few years, laboratories around the world have been abuzz with ‘RNA interference’ or RNAi, a potent technique for turning off the genes of model organisms at will. Nematode worms, for example, can be fed with RNA that silences specific genes inside their cells.
It had been thought that RNAi could not be used in mammalian cells. Thomas Tuschl, and colleagues, from the University of Gottingen in Germany, now show that short double-stranded RNAs or ‘siRNAs’ can indeed induce RNAi in human cells grown in culture. The researchers silence a selection of genes to prove their point.
        This new methodology should help study the many genes of unknown function being identified in the continuing sequencing of the entire human genome. It may also open the way to therapeutic applications of siRNAs.
In an accompanying News and Views article, Brenda L. Bass of the Howard Hughes Medical Institute, University of Utah, Salt Lake City, describes the results as “good news for cells and researchers”.
CONTACT:
Thomas Tuschl tel +49 551 517 7561, e-mail ttuschl@mpibpc.gwdg.de
Brenda Bass tel +1 801 581 4884, e-mail bbass@howard.genetics.utah.edu

[411466] CLIMATE: FORESTS SINK IN ESTIMATION (pp466-469, 469-472; N&V)
Some makers of environmental policy hope that forests could counter global warming by absorbing much of the extra carbon dioxide that humans are adding to the atmosphere, and that planting forests could be a substitute for reducing emissions. Now two studies of North American pine forests suggest that such hopes are overly optimistic.
Ram Oren, of Duke University, Durham, North Carolina, and colleagues found that a plantation of trees growing in air that contained about 0.06% carbon dioxide, as opposed to the current 0.036%, increased their growth for only three years. After this, they reverted to their original growth rate.
The trees’ capacity to respond to carbon fertilization was limited by a shortage of other nutrients, notably nitrogen. When the researchers added nitrogen to their plots, the growth rate of the trees increased again.
Another potential carbon sink in forests is the leaf-litter layer and soil. Again, the news regarding this environment and climate change is unpromising.
Duke University’s William Schlesinger and John Lichter, of Bowden College, Brunswick, Maine, who studied the same forest plots used by Oren’s team, report this week that the total amount of litter increases in a carbon-dioxide-enriched atmosphere, but so does the rate at which it is broken down.
The carbon is then returned to the atmosphere whence it came, rather than incorporated into the soil. Schlesinger and Lichter estimate that, once a leaf falls from the tree, its carbon is back in the atmosphere in about three years.
“Information such as this will be essential in using models to make global extrapolations of the effects of increasing atmospheric CO2 on the carbon cycle as a whole,” write Eric A. Davidson and Adam I. Hirsch of the Woods Hole Research Center, Massachusetts, in an accompanying News and Views article.
CONTACT:
Ram Oren tel +1 919 613 8032, e-mail ramoren@duke.edu
William H Schlesinger tel +1 919 660 7400, e-mail schlesin@duke.edu
Eric Davidson tel +1 508 540 9900, e-mail edavidson@whrc.org

[411476] BRAIN: BODY WORK (pp476-480; N&V)
That flies can learn smells even when critical nerve endings in their brains are blocked is helping to sort out the steps that keep memories in mind. By silencing synapses — the connections between nerve cells — Tim Tully, of the Cold Spring Harbour Laboratory, New York, and colleagues have shown that an idle mushroom body — part of the fly brain involved in olfactory associative learning — has no effect on the insects’ memory-making.
        Tully’s team used a heat-sensitive gene mutation to show that synaptic transmission from the ‘mushroom body’ is required during memory retrieval, but not during acquisition or storage.
Research like this helps illuminate how brains of different sizes cope with learning and remembering, Randolf Menzel and Uli Müller of the Freie Universit'¤t Berlin, Germany, explain in an accompanying News and Views article.
CONTACT:
Tim Tully tel +1 516 367 6861, e-mail tully@cshl.org
Randolf Menzel tel +49 30 838 3930, e-mail menzel@neurobiologie.fu-berlin.de

[411457] PHYSICS: MAGNESIUM DIBORIDE UPDATE (pp457-460)
The recent discovery of superconductivity at 39 K in magnesium diboride (MgB2) established this simple binary compound as having the highest bulk superconducting temperature of any non-copper-oxide material. This week, D. G. Hinks of the Argonne National Laboratory, Illinois, and colleagues present the latest in a string of papers looking at the mechanism of superconductivity in MgB2. Theirs examines the total isotope effect.
This effect, in which atom masses are manipulated to change the phonon frequencies, is a fundamental test of the conventional Bardeen–Cooper–Schrieffer (BCS) mechanism of superconductivity. By determining the magnesium isotope effect, Hinks’ team build on previous estimates of the boron isotope effect, setting new constraints for models of MgB2 superconductivity.
CONTACT:
D G Hinks tel +1 630 252 5471, e-mail hinks@anl.gov

[411480] BRAIN: LEPTIN RESISTANCE EXPLAINED (pp480-484)
Neurons in the hypothalamus receive and process peripheral signals that transmit information concerning energy stores. Many human obesity conditions are characterized by a resistance to leptin — a hormone controlling food intake and storage — in this region of the brain. This week, Malcolm J. Low of the Oregon Health Sciences University, Portland, and colleagues go some way to explaining the neuronal mechanisms behind this.
Low’s team describes the electrophysiological properties of an important class of leptin-sensitive neurons, proopiomelanocortin neurons. They studied these neurons by making them visible through the targeted expression of green fluorescent protein in transgenic mice.
CONTACT:
Malcolm Low tel +1 503 494 4672, e-mail low@ohsu.edu

[411446] SPACE: PLUTO ONE OF MANY? (pp446-447; N&V)
Pluto and its moon Charon are the only members of an ancient ring of icy bodies, the Kuiper belt, orbiting the Sun beyond Neptune, for which accurate sizes are known. In this week’s Nature, David Jewitt of the Institute for Astronomy, Honolulu, Hawaii, and colleagues present simultaneous optical and submillimetre wavelength measurements of a bright object in the belt, Varuna, determining its size and reflectivity for the first time. Varuna is 900 kilometres in diameter, and more reflective than most other asteroids for which accurate measurements are available, though less reflective than Pluto and Charon.
“We can now imagine that bodies even larger and more distant than Pluto will be found. Such objects have so far escaped detection because of their extreme faintness, due in part to the feeble illuminating light from the Sun and in part to their very dark surfaces,” explain S. C. Tegler of Northern Arizona University, Flagstaff, and W. Romanishin of the University of Oklahoma, Norman, in an accompanying News and Views article.
CONTACT:
David Jewitt tel +1 808 956 6664, e-mail jewitt@ifa.hawaii.edu
S. C. Tegler tel +1 520 523 9382, e-mail Stephen.tegler@nau.edu

See also http://www.ifa.hawaii.edu/faculty/jewitt/kb.html

[411437] …AND FINALLY: WORTH THE WEIGHT (p437)
The ancient civilizations of the Near East and the Mediterranean used a plethora of different weight measurements — the Syrian talent, the Ugarit shekel and the Egyptian kdt (sic) to name just three — that make the metric/imperial divide seem like a doddle. Now researchers have found all these weights could actually be united by a simple conversion system.
The Ugarit and Syrian shekels, and the Egyptian kdt, for example, all weigh 9.4 grams. And this is also four-fifths of the weight of a Hittite shekel, making conversion a matter of simple arithmetic. Similar sums can be done to unite the other metrics of the region. In a Brief Communication, Alfredo Mederos, of the Universidad Complutense, Madrid, and Clifford Lamberg-Karlovsky, of Harvard University, Cambridge, Massachusetts, argue that such conversion systems were crucial to the development of the region’s trade networks.
CONTACT:
Clifford Lamberg-Karlovsky tel +1 617 496 8162, e-mail karlovsk@fas.harvard.edu


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