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Frank H. Westheimer (1912–2007)
2007 Nature
doi: 10.1038/447543apmid: 17538611
Pioneering chemist at the interface with biology.
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doi: 10.1038/447543apmid: 17538611
Pioneering chemist at the interface with biology.
Bishop, Nicholas A.; Guarente, Leonard
doi: 10.1038/nature05904pmid: 17538612
Dietary restriction extends lifespan and retards age-related disease in many species and profoundly alters endocrine function in mammals. However, no causal role of any hormonal signal in diet-restricted longevity has been demonstrated. Here we show that increased longevity of diet-restricted Caenorhabditis elegans requires the transcription factor gene skn-1 acting in the ASIs, a pair of neurons in the head. Dietary restriction activates skn-1 in these two neurons, which signals peripheral tissues to increase metabolic activity. These findings demonstrate that increased lifespan in a diet-restricted metazoan depends on cell non-autonomous signalling from central neuronal cells to non-neuronal body tissues, and suggest that the ASI neurons mediate diet-restriction-induced longevity by an endocrine mechanism.
Panowski, Siler H.; Wolff, Suzanne; Aguilaniu, Hugo; Durieux, Jenni; Dillin, Andrew
doi: 10.1038/nature05837pmid: 17476212
Reduced food intake as a result of dietary restriction increases the lifespan of a wide variety of metazoans and delays the onset of multiple age-related pathologies. Dietary restriction elicits a genetically programmed response to nutrient availability that cannot be explained by a simple reduction in metabolism or slower growth of the organism. In the nematode worm Caenorhabditis elegans, the transcription factor PHA-4 has an essential role in the embryonic development of the foregut and is orthologous to genes encoding the mammalian family of Foxa transcription factors, Foxa1, Foxa2 and Foxa3. Foxa family members have important roles during development, but also act later in life to regulate glucagon production and glucose homeostasis, particularly in response to fasting. Here we describe a newly discovered, adult-specific function for PHA-4 in the regulation of diet-restriction-mediated longevity in C. elegans. The role of PHA-4 in lifespan determination is specific for dietary restriction, because it is not required for the increased longevity caused by other genetic pathways that regulate ageing.
Tessier, Peter M.; Lindquist, Susan
doi: 10.1038/nature05848pmid: 17495929
Prions are proteins that can switch to self-perpetuating, infectious conformations. The abilities of prions to replicate, form structurally distinct strains, and establish and overcome transmission barriers between species are poorly understood. We exploit surface-bound peptides to overcome complexities of investigating such problems in solution. For the yeast prion Sup35, we find that the switch to the prion state is controlled with exquisite specificity by small elements of primary sequence. Strikingly, these same sequence elements govern the formation of distinct self-perpetuating conformations (prion strains) and determine species-specific seeding activities. A Sup35 chimaera that traverses the transmission barrier between two yeast species possesses the critical sequence elements from both. Using this chimaera, we show that the influence of environment and mutations on the formation of species-specific strains is driven by selective recognition of either sequence element. Thus, critical aspects of prion conversion are enciphered by subtle differences between small, highly specific recognition elements.
doi: 10.1038/nature05867pmid: 17538613
Planetary systems are formed within the disks of dust and gas around young stars that are the left-overs from the star formation process. The terrestrial planet forming regions of these disks subtend tiny angles, way beyond the angular resolution of even the largest ground- and space-based telescopes. Now using a new instrument at the Keck Interferometer, gases including water vapour and atomic hydrogen have been observed within one astronomical unit (one Sun–Earth distance) of the young star MWC 480. The water vapour was probably produced by the sublimation of migrating icy bodies, and it could provide a reservoir of water for the production of terrestrial planets.
Doiron-Leyraud, Nicolas; Proust, Cyril; LeBoeuf, David; Levallois, Julien; Bonnemaison, Jean-Baptiste; Liang, Ruixing; Bonn, D. A.; Hardy, W. N.; Taillefer, Louis
doi: 10.1038/nature05872pmid: 17538614
Two papers in this issue report notable contributions towards an understanding of high-temperature superconductivity, still an elusive goal after more than 20 years of intensive research. Doiron-Leyraud et al. report the observation of a Fermi surface in a high-temperature superconductor, a phenomenon regarded as the classic signature of a metal. Gomes et al. tackled the long-standing question of whether the gap in the electronic energy spectrum at temperatures above the critical temperature of a high-temperature superconductor is associated with electron pairing. They find that it is. With these two elegant experimental papers adding some solid new data to the mix, it is the turn of the theorists to work out the implications for superconductivity mechanisms.
Gomes, Kenjiro K.; Pasupathy, Abhay N.; Pushp, Aakash; Ono, Shimpei; Ando, Yoichi; Yazdani, Ali
doi: 10.1038/nature05881pmid: 17538615
Two papers in this issue report notable contributions towards an understanding of high-temperature superconductivity, still an elusive goal after more than 20 years of intensive research. Doiron-Leyraud et al. report the observation of a Fermi surface in a high-temperature superconductor, a phenomenon regarded as the classic signature of a metal. Gomes et al. tackled the long-standing question of whether the gap in the electronic energy spectrum at temperatures above the critical temperature of a high-temperature superconductor is associated with electron pairing. They find that it is. With these two elegant experimental papers adding some solid new data to the mix, it is the turn of the theorists to work out the implications for superconductivity mechanisms.
Dery, H.; Dalal, P.; Cywiński, Ł.; Sham, L. J.
doi: 10.1038/nature05833pmid: 17538616
This paper reports a theoretical design that is a conceptual step forward; spin accumulation is used as the basis of a semiconductor computer circuit rather than flow of spin. A logic gate in this design consists of five magnetic leads on top of a semiconductor layer and is found to perform fast logic operations. The idea is further developed by demonstrating the capability to interconnect a large number of gates.
Sriver, Ryan L.; Huber, Matthew
doi: 10.1038/nature05785pmid: 17538617
Tropical cyclones are known to mix the upper layers of the ocean, a process that 'pumps' heat downwards and thereby cools the ocean surface on local scales. It has been suggested that they may play an important role in ocean mixing at the global scale, and new calculations suggest that tropical cyclones are indeed responsible for significant cooling and vertical mixing of the surface ocean in tropical regions. Heat pumped downwards must be balanced by heat transport towards the poles, so some 15% of peak poleward oceanic heat transport may be associated with tropical cyclone-induced mixing. The amount of mixing induced by tropical cyclones is also related to sea surface temperature, suggesting that future changes in tropical sea surface temperatures may have significant effects on ocean circulation and ocean heat transport, as both processes are affected by ocean mixing. Climate change models could benefit from taking these effects into account. See also last week's Concepts essay, in which Martin Visbeck argues that the 'pulling power' of upwardly mobile ocean waters is an increasing factor in ocean mixing. Elsewhere in this issue, Quirin Schiermeier takes a broad view of recent work on ocean mixing and the US National Hurricane Center releases its latest storm predictions.
Wolf, Max; van Doorn, G. Sander; Leimar, Olof; Weissing, Franz J.
doi: 10.1038/nature05835pmid: 17538618
Although 'personalities' such as boldness, aggressive behaviour and risk avoidance have been shown to exist in more than sixty animal species, from primates to ants, explaining their existence in terms of evolution has been a puzzle. Surely, evolution should not favour the maintenance of different personalities, but rather the convergence towards a single one. In a numerical life-history model, Wolf et al. show that the evolution of animal personalities, defined as consistent sets of behaviours shown in a variety of contexts, is related to an adaptive response to life-history trade-offs. In this model, decisions on trade-offs between current and future reproduction condition the response of individuals to risky situations, and this may be the basis for animal personalities and their maintenance in populations.
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