THE REAL MOTIONS OF THE FIXED STARS     

Williamson AW 《Science (New York, N.Y.)》1892,20(504):192-193

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Island biology and ecosystem functioning in epiphytic soil communities     

Wardle DA  Yeates GW  Barker GM  Bellingham PJ  Bonner KI  Williamson WM 《Science (New York, N.Y.)》2003,301(5640):1717-1720

Although island attributes such as size and accessibility to colonizing organisms can influence community structure, the consequences of these for ecosystem functioning are little understood. A study of the suspended soils of spatially discrete epiphytes or treetop "islands" in the canopies of New Zealand rainforest trees revealed that different components of the decomposer community responded either positively or negatively to island size, as well as to the tree species that the islands occurred in. This in turn led to important differences between islands in the rates of ecosystem processes driven by the decomposer biota. This system serves as a model for better understanding how attributes of both real and habitat islands may affect key ecosystem functions through determining the community structure of organisms that drive these functions.  相似文献   

Crystal structure of the long-chain fatty acid transporter FadL     

van den Berg B  Black PN  Clemons WM  Rapoport TA 《Science (New York, N.Y.)》2004,304(5676):1506-1509

The mechanisms by which hydrophobic molecules, such as long-chain fatty acids, enter cells are poorly understood. In Gram-negative bacteria, the lipopolysaccharide layer in the outer membrane is an efficient barrier for fatty acids and aromatic hydrocarbons destined for biodegradation. We report crystal structures of the long-chain fatty acid transporter FadL from Escherichia coli at 2.6 and 2.8 angstrom resolution. FadL forms a 14-stranded beta barrel that is occluded by a central hatch domain. The structures suggest that hydrophobic compounds bind to multiple sites in FadL and use a transport mechanism that involves spontaneous conformational changes in the hatch.  相似文献   

Plant mycoplasmas: a cultivable spiroplasma causes corn stunt disease     

Williamson DL  Whitcomb RF 《Science (New York, N.Y.)》1975,188(4192):1018-1020

A spiroplasma can be isolated and grown continuously in cell-free medium from stunted corn or from Drosophila injected with sap expressed from diseased corn. The organism is serologically related to, but not identical with, Spiroplasma citri, the causative agent of citrus stubborn disease. Leafhopers injected with cultured organisms induced typical symptoms of the corn stunt disease when placed on previously healthy corn plants.  相似文献   

Genome-sequencing anniversary. Genomics and clinical relevance     

Hudson T 《Science (New York, N.Y.)》2011,331(6017):547

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210th meeting of the American Astronomical Society. Black holes: galactic homebodies?     

Siegfried T 《Science (New York, N.Y.)》2007,316(5830):1420

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Membrane proteins of the endoplasmic reticulum induce high-curvature tubules     

Hu J  Shibata Y  Voss C  Shemesh T  Li Z  Coughlin M  Kozlov MM  Rapoport TA  Prinz WA 《Science (New York, N.Y.)》2008,319(5867):1247-1250

The tubular structure of the endoplasmic reticulum (ER) appears to be generated by integral membrane proteins, the reticulons and a protein family consisting of DP1 in mammals and Yop1p in yeast. Here, individual members of these families were found to be sufficient to generate membrane tubules. When we purified yeast Yop1p and incorporated it into proteoliposomes, narrow tubules (approximately 15 to 17 nanometers in diameter) were generated. Tubule formation occurred with different lipids; required essentially only the central portion of the protein, including its two long hydrophobic segments; and was prevented by mutations that affected tubule formation in vivo. Tubules were also formed by reconstituted purified yeast Rtn1p. Tubules made in vitro were narrower than normal ER tubules, due to a higher concentration of tubule-inducing proteins. The shape and oligomerization of the "morphogenic" proteins could explain the formation of the tubular ER.  相似文献   

Molecular biology. Breaking the silence     

Owen-Hughes T  Bruno M 《Science (New York, N.Y.)》2004,303(5656):324-325

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Molecular mechanisms for the functionality of lubricant additives     

Mosey NJ  Müser MH  Woo TK 《Science (New York, N.Y.)》2005,307(5715):1612-1615

Wear limits the life-span of many mechanical devices with moving parts. To reduce wear, lubricants are frequently enriched with additives, such as zinc phosphates, that form protective films on rubbing surfaces. Using first-principles molecular dynamics simulations of films derived from commercial additives, we unraveled the molecular origin of how antiwear films can form, function, and dissipate energy. These effects originate from pressure-induced changes in the coordination number of atoms acting as cross-linking agents to form chemically connected networks. The proposed mechanism explains a diverse body of experiments and promises to prove useful in the rational design of antiwear additives that operate on a wider range of surface materials, with reduced environmental side effects.  相似文献   

American Physical Society meeting. Gravity probe researchers report 'glimpses' of long-awaited payoff     

Siegfried T 《Science (New York, N.Y.)》2007,316(5824):538-539

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