Retraction     

Horsewill AJ  Jones NH  Caciuffo R 《Science (New York, N.Y.)》2002,298(5596):1171

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Sequence-directed DNA translocation by purified FtsK     

Pease PJ  Levy O  Cost GJ  Gore J  Ptacin JL  Sherratt D  Bustamante C  Cozzarelli NR 《Science (New York, N.Y.)》2005,307(5709):586-590

DNA translocases are molecular motors that move rapidly along DNA using adenosine triphosphate as the source of energy. We directly observed the movement of purified FtsK, an Escherichia coli translocase, on single DNA molecules. The protein moves at 5 kilobases per second and against forces up to 60 piconewtons, and locally reverses direction without dissociation. On three natural substrates, independent of its initial binding position, FtsK efficiently translocates over long distances to the terminal region of the E. coli chromosome, as it does in vivo. Our results imply that FtsK is a bidirectional motor that changes direction in response to short, asymmetric directing DNA sequences.  相似文献   

Spindle multipolarity is prevented by centrosomal clustering     

Quintyne NJ  Reing JE  Hoffelder DR  Gollin SM  Saunders WS 《Science (New York, N.Y.)》2005,307(5706):127-129

Most tumor cells are characterized by increased genomic instability and chromosome segregational defects, often associated with hyperamplification of the centrosome and the formation of multipolar spindles. However, extra centrosomes do not always lead to multipolarity. Here, we describe a process of centrosomal clustering that prevented the formation of multipolar spindles in noncancer cells. Noncancer cells needed to overcome this clustering mechanism to allow multipolar spindles to form at a high frequency. The microtubule motor cytoplasmic dynein was a critical part of this coalescing machinery, and in some tumor cells overexpression of the spindle protein NuMA interfered with dynein localization, promoting multipolarity.  相似文献   

National Speleological Society     

Nicholas G 《Science (New York, N.Y.)》1954,120(3113):5A

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National Speleological Society (E4)     

Nicholas BG  Thrailkill JV 《Science (New York, N.Y.)》1963,139(3555):636

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Senate passes back gene-splice cup     

Wade N 《Science (New York, N.Y.)》1978,200(4348):1368

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Issues in the analysis of contemporary farm protest     

Nicholas R. Ellig 《Agriculture and Human Values》1985,2(2):44-47

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Statement on scientific publication and security     

Atlas R  Campbell P  Cozzarelli NR  Curfman G  Enquist L  Fink G  Flanagin A  Fletcher J  George E  Hammes G  Heyman D  Inglesby T  Kaplan S  Kennedy D  Krug J  Levinson R  Marcus E  Metzger H  Morse SS  O'Brien A  Onderdonk A  Poste G  Renault B  Rich R  Rosengard A  Salzburg S  Scanlan M  Shenk T  Tabor H  Varmus H  Wimmer E  Yamamoto K;Journal Editors  Authors Group 《Science (New York, N.Y.)》2003,299(5610):1149

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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   

Recombinant DNA: NIH rules broken in insulin gene project     

Wade N 《Science (New York, N.Y.)》1977,197(4311):1342-1345

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