REQUIREMENTS OF A MONOGRAPH ON THE CHEMISTRY OF CELLULOSE     

Wise LE 《Science (New York, N.Y.)》1921,54(1403):479-482

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Lignin-like compounds and sporopollenin coleochaete, an algal model for land plant ancestry     

Delwiche CF  Graham LE  Thomson N 《Science (New York, N.Y.)》1989,245(4916):399-401

Unusual cell wall structure and resistance to microbial degradation led to an investigation of resistant biopolymers in Coleochaete (Chlorophyta, class Charophyceae), a green alga on the evolutionary lineage that led to land plants. In Coleochaete that are undergoing sexual reproduction, vegetative cell walls contain material similar to lignin, a substance generally thought absent from green algae, and the zygote wall includes sporopollenin. Knowledge of chemically resistant compounds in Coleochaete may facilitate interpretation of the fossil record. Placental transfer cells in Coleochaete orbicularis and in the hornwort Anthoceros survive acetolysis and contain lignin-like compounds, implying a close relation between these taxa.  相似文献   

Virus-like particles in normal and tumorous tissues of Drosophila     

Akai H  Gateff E  Davis LE  Schneiderman HA 《Science (New York, N.Y.)》1967,157(3790):810-813

A new virus-like particle has been found in Drosophila. Thus far it has been detected only in electron micrographs of certain cells capable of division, such as those in larval imaginal disks, cell lines derived from imaginal disks, cells from a genetically controlled brain tumor, and adult gut cells. It appears to be slightly elliptical in shape, about 37 millimicrons by 45 millimicrons, and occurs in both the nucleus and cytoplasm. From the evidence it is suggested that the particle is a new virus.  相似文献   

The involvement of the anterior cingulate cortex in remote contextual fear memory   总被引：1，自引：0，他引：1  

Frankland PW  Bontempi B  Talton LE  Kaczmarek L  Silva AJ 《Science (New York, N.Y.)》2004,304(5672):881-883

Although the molecular, cellular, and systems mechanisms required for initial memory processing have been intensively investigated, those underlying permanent memory storage remain elusive. We present neuroanatomical, pharmacological, and genetic results demonstrating that the anterior cingulate cortex plays a critical role in remote memory for contextual fear conditioning. Imaging of activity-dependent genes shows that the anterior cingulate is activated by remote memory and that this activation is impaired by a null alpha-CaMKII mutation that blocks remote memory. Accordingly, reversible inactivation of this structure in normal mice disrupts remote memory without affecting recent memory.  相似文献   

Hsp90 potentiates the rapid evolution of new traits: drug resistance in diverse fungi   总被引：1，自引：0，他引：1  

Cowen LE  Lindquist S 《Science (New York, N.Y.)》2005,309(5744):2185-2189

Hsp90 is a molecular chaperone for many signal transducers and may influence evolution by releasing previously silent genetic variation in response to environmental change. In fungi separated by approximately 800 million years of evolution, Hsp90 potentiated the evolution of drug resistance in a different way, by enabling new mutations to have immediate phenotypic consequences. Resistance was abrogated by Hsp90 inhibitors and by febrile temperatures, suggesting new therapeutic strategies and a clinical benefit of fever. During selection in a human host, drug resistance that was initially Hsp90-dependent evolved toward independence. Thus, Hsp90 can act in diverse ways to couple environmental contingency to the emergence and fixation of new traits.  相似文献   

Readjustments of the Loup Rivers: Examples of Abstraction Due to Unequal Declivities     

Hicks LE 《Science (New York, N.Y.)》1892,19(485):288-290

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National character does not reflect mean personality trait levels in 49 cultures     

Terracciano A  Abdel-Khalek AM  Adám N  Adamovová L  Ahn CK  Ahn HN  Alansari BM  Alcalay L  Allik J  Angleitner A  Avia MD  Ayearst LE  Barbaranelli C  Beer A  Borg-Cunen MA  Bratko D  Brunner-Sciarra M  Budzinski L  Camart N  Dahourou D  De Fruyt F  de Lima MP  del Pilar GE  Diener E  Falzon R  Fernando K  Ficková E  Fischer R  Flores-Mendoza C  Ghayur MA  Gülgöz S  Hagberg B  Halberstadt J  Halim MS  Hrebícková M  Humrichouse J  Jensen HH  Jocic DD  Jónsson FH  Khoury B  Klinkosz W  Knezević G  Lauri MA  Leibovich N  Martin TA 《Science (New York, N.Y.)》2005,310(5745):96-100

Most people hold beliefs about personality characteristics typical of members of their own and others' cultures. These perceptions of national character may be generalizations from personal experience, stereotypes with a "kernel of truth," or inaccurate stereotypes. We obtained national character ratings of 3989 people from 49 cultures and compared them with the average personality scores of culture members assessed by observer ratings and self-reports. National character ratings were reliable but did not converge with assessed traits. Perceptions of national character thus appear to be unfounded stereotypes that may serve the function of maintaining a national identity.  相似文献   

Impairment of muscle stretch reflexes in tick paralysis     

ESPLIN DW  PHILIP CB  HUGHES LE 《Science (New York, N.Y.)》1960,132(3432):958-959

Experiments with tick-paralyzed dogs and woodchucks have shown impairment of stretch reflexes in addition to partial paralysis at the neuromuscular junction. Stretch reflexes disappear very early during paralysis, whereas nociceptive reflexes do not appear to be directly affected. The early incoordination and the ascending nature of the paralysis may be related to impairment of stretch reflex pathways.  相似文献   

The role of CCR7 in TH1 and TH2 cell localization and delivery of B cell help in vivo     

Randolph DA  Huang G  Carruthers CJ  Bromley LE  Chaplin DD 《Science (New York, N.Y.)》1999,286(5447):2159-2162

Subsets of murine CD4+ T cells localize to different areas of the spleen after adoptive transfer. Na?ve and T helper 1 (TH1) cells, which express the chemokine receptor CCR7, are home to the periarteriolar lymphoid sheath, whereas activated TH2 cells, which lack CCR7, form rings at the periphery of the T cell zones near B cell follicles. Retroviral transduction of TH2 cells with CCR7 forces them to localize in a TH1-like pattern and inhibits their participation in B cell help in vivo but not in vitro. Thus, differential expression of chemokine receptors results in unique cellular migration patterns that are important for effective immune responses.  相似文献   

Leaching: use of a thermophilic and chemoautotrophic microbe     

Brierley CL  Murr LE 《Science (New York, N.Y.)》1973,179(4072):488-490

A chemoautotrophic, thermophilic, and acidophilic microorganism capable of oxidizing reduced sulfur and iron compounds and leaching concentrates of molybdenite and chalcopyrite at 60 degrees C has been characterized by transmission and scanning electron microscopy. This constitutes the first direct observations of microorganisms on ore fines.  相似文献