Axle-less F1-ATPase rotates in the correct direction     

Furuike S  Hossain MD  Maki Y  Adachi K  Suzuki T  Kohori A  Itoh H  Yoshida M  Kinosita K 《Science (New York, N.Y.)》2008,319(5865):955-958

F1-adenosine triphosphatase (ATPase) is an ATP-driven rotary molecular motor in which the central gamma subunit rotates inside a cylinder made of three alpha and three beta subunits alternately arranged. The rotor shaft, an antiparallel alpha-helical coiled coil of the amino and carboxyl termini of the gamma subunit, deeply penetrates the central cavity of the stator cylinder. We truncated the shaft step by step until the remaining rotor head would be outside the cavity and simply sat on the concave entrance of the stator orifice. All truncation mutants rotated in the correct direction, implying torque generation, although the average rotary speeds were low and short mutants exhibited moments of irregular motion. Neither a fixed pivot nor a rigid axle was needed for rotation of F1-ATPase.  相似文献   

Void structure in colloidal dispersions     

Ito K  Yoshida H  Ise N 《Science (New York, N.Y.)》1994,263(5143):66-68

The time evolution of void structures in highly purified polymer latex dispersions was studied with a confocal laser scanning microscope. In such dispersions, which were initially homogeneous, the voids grew with time when the dispersions were kept standing and formed more quickly in the internal material than in material close to the glass-dispersion interface. Void formation is thus not an artifact arising from the presence of the interface. A similar structural inhomogeneity, in apparently homogeneous systems, is discussed for simple ionic solutions, ionic polymer solutions, and Langmuir-Blodgett films.  相似文献   

Pulmonary alveolar hypoxia: release of prostaglandins and other humoral mediators   总被引：6，自引：0，他引：6  

S I Said  T Yoshida  S Kitamura  C Vreim 《Science (New York, N.Y.)》1974,185(4157):1181-1183

Hypoxic ventilation of isolated perfused cat lungs caused the frequent appearance in pulmonary perfusates of biologically active substances, which included prostaglandins or prostaglandin-like compounds. In anesthetized cats, inhibition of prostaglandin biosynthesis with infusions of aspirin (more than 50 milligrams per kilogram) reduced the pulmonary vasoconstrictor and bronchoconstrictor responses to hypoxic breathing.  相似文献   

Compound ocellus of a starfish: its function     

Yoshida M  Ohtsuki H 《Science (New York, N.Y.)》1966,153(3732):197-198

The relative effect of light in inducing downward movements of the tips of isolated arms of Asterias amurensis is maximal at 485 millimicrons when the compound ocellus is intact; at 504 millimicrons when the ocellus has been removed. This finding suggests the coexistence of two photoreceptive systems, ocellar and nonocellar.  相似文献   

Induction of inflammatory arthropathy resembling rheumatoid arthritis in mice transgenic for HTLV-I   总被引：28，自引：0，他引：28  

Y Iwakura  M Tosu  E Yoshida  M Takiguchi  K Sato  I Kitajima  K Nishioka  K Yamamoto  T Takeda  M Hatanaka 《Science (New York, N.Y.)》1991,253(5023):1026-1028

Human T cell leukemia virus type-I (HTLV-I) is the etiologic agent of adult T cell leukemia and has also been suggested to be involved in other diseases such as chronic arthritis or myelopathy. To elucidate pathological roles of the virus in disease, transgenic mice were produced that carry the HTLV-I genome. At 2 to 3 months of age, many of the mice developed chronic arthritis resembling rheumatoid arthritis. Synovial and periarticular inflammation with articular erosion caused by invasion of granulation tissues were marked. These observations suggest a possibility that HTLV-I is one of the etiologic agents of chronic arthritis in humans.  相似文献   

Evidence for brainstem structures participating in oculomotor integration     

Nakamagoe K  Iwamoto Y  Yoshida K 《Science (New York, N.Y.)》2000,288(5467):857-859

The cerebellar flocculus has been implicated in vestibulo-oculomotor control. One major central input to this structure originates from brainstem cells in the paramedian tract (PMT), whose function is unknown. Here it is reported that PMT cells in the pons carry vestibular and eye movement signals and their pharmacological inactivation produces a leaky integrator combined with vestibular imbalance. The results suggest that PMT cells provide the cerebellum with sensory and motor signals that are essential for velocity-to-position integration, a common premotor process that is required in all motor systems.  相似文献   

Observation of X-ray lines from a gamma-ray burst (GRB991216): evidence of moving ejecta from the progenitor     

Piro L  Garmire G  Garcia M  Stratta G  Costa E  Feroci M  Mészáros P  Vietri M  Bradt H  Frail D  Frontera F  Halpern J  Heise J  Hurley K  Kawai N  Kippen RM  Marshall F  Murakami T  Sokolov VV  Takeshima T  Yoshida A 《Science (New York, N.Y.)》2000,290(5493):955-958

We report on the discovery of two emission features observed in the x-ray spectrum of the afterglow of the gamma-ray burst (GRB) of 16 December 1999 by the Chandra X-ray Observatory. These features are identified with the Ly(alpha) line and the narrow recombination continuum by hydrogenic ions of iron at a redshift z = 1.00 +/- 0.02, providing an unambiguous measurement of the distance of a GRB. Line width and intensity imply that the progenitor of the GRB was a massive star system that ejected, before the GRB event, a quantity of iron approximately 0.01 of the mass of the sun at a velocity approximately 0.1 of the speed of light, probably by a supernova explosion.  相似文献   

Single chain alkali resistance in hemoglobin Rainier: beta 145 tyrosine-histidine     

G Stamatoyannopoulos  A Yoshida 《Science (New York, N.Y.)》1969,166(908):1005-1006

The mechanism of alkali resistance in hemoglobin Rainier, an adult human hemoglobin variant (beta 145 tyrosinie --> histidinie), has been investigated. Alkali denaturation kinetics, electrophoretic and hybridization study. and ultracentrifuge analysis provided evidence for a monomeric beta Rainiier chain resisting denaturation at alkaline pH. These data provide evidence for a previously unrecognized effect of a single amino acid substitution, that is, the change of the alkali denaturation properties of monomneric chains.  相似文献   

Comment on "Status and trends of amphibian declines and extinctions worldwide"     

Pimenta BV  Haddad CF  Nascimento LB  Cruz CA  Pombal JP 《Science (New York, N.Y.)》2005,309(5743):1999; author reply 1999

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Protostellar feedback halts the growth of the first stars in the universe     

Hosokawa T  Omukai K  Yoshida N  Yorke HW 《Science (New York, N.Y.)》2011,334(6060):1250-1253

The first stars fundamentally transformed the early universe by emitting the first light and by producing the first heavy elements. These effects were predetermined by the mass distribution of the first stars, which is thought to have been fixed by a complex interplay of gas accretion and protostellar radiation. We performed radiation-hydrodynamics simulations that followed the growth of a primordial protostar through to the early stages as a star with thermonuclear burning. The circumstellar accretion disk was evaporated by ultraviolet radiation from the star when its mass was 43 times that of the Sun. Such massive primordial stars, in contrast to the often-postulated extremely massive stars, may help explain the fact that there are no signatures of the pair-instability supernovae in abundance patterns of metal-poor stars in our galaxy.  相似文献