Amplified dihydrofolate reductase genes in unstably methotrexate-resistant cells are associated with double minute chromosomes.

abstract：:NAD+ glycohydrolase activity is found at high levels in submitochondrial particles. It leads to the reaction products ADP-ribose, nicotinamide, and small amounts of 5'-AMP. Furthermore, submitochondrial particles catalyze the exchange reaction: [adenosine-14C]ADP-ribose + NAD+ in equilibrium [adenosine-14C]-NAD+ + ADP...

journal_title：Proceedings of the National Academy of Sciences of the United States of America

authors： Richter C,Winterhalter KH,Baumhüter S,Lötscher HR,Moser B

更新日期：1983-06-01 00:00:00

abstract：:We have used methods that have allowed simultaneous fluorescent staining of intracellular actin together with either myosin, filamin, or tubulin in normal rat kidney fibroblasts in monolayer culture. In the main portions of the cell body, the actin, myosin, and filamin are all present in two structures: in one, the th...

journal_title：Proceedings of the National Academy of Sciences of the United States of America

authors： Heggeness MH,Wang K,Singer SJ

更新日期：1977-09-01 00:00:00

abstract：:The endosperm of cereal grains is one of the most valuable products of modern agriculture. Cereal endosperm development comprises different phases characterized by mitotic cell proliferation, endoreduplication, the accumulation of storage compounds, and programmed cell death. Although manipulation of these processes c...

journal_title：Proceedings of the National Academy of Sciences of the United States of America

authors： Sabelli PA,Liu Y,Dante RA,Lizarraga LE,Nguyen HN,Brown SW,Klingler JP,Yu J,LaBrant E,Layton TM,Feldman M,Larkins BA

更新日期：2013-05-07 00:00:00

abstract：:This paper describes experiments in which cytosolic Ca2+ concentrations ([Ca2+]i) and catecholamine release were measured in two populations of chromaffin cells stimulated with a solution enriched in K+ (100 mM). Once depolarized, external Ca2+ or Ba2+ ions were offered to cells either as a single 2.5 mM step or as a ...

journal_title：Proceedings of the National Academy of Sciences of the United States of America

authors： Michelena P,García-Pérez LE,Artalejo AR,García AG

更新日期：1993-04-15 00:00:00

abstract：:Natural killer T (NKT) cells provide an innate-type immune response upon T cell receptor interaction with CD1d-presented antigens. We demonstrate through equilibrium tetramer binding and antigen presentation assays with Valpha14i-positive NKT cell hybridomas that the Sphingomonas glycolipid alpha-galacturonosyl cerami...

journal_title：Proceedings of the National Academy of Sciences of the United States of America

authors： Wu D,Zajonc DM,Fujio M,Sullivan BA,Kinjo Y,Kronenberg M,Wilson IA,Wong CH

更新日期：2006-03-14 00:00:00

abstract：:The non-long terminal repeat (LTR) retrotransposon, R2, encodes a sequence-specific endonuclease responsible for its insertion at a unique site in the 28S rRNA genes of arthropods. Although most non-LTR retrotransposons encode an apurinic-like endonuclease upstream of a common reverse transcriptase domain, R2 and many...

journal_title：Proceedings of the National Academy of Sciences of the United States of America

authors： Yang J,Malik HS,Eickbush TH

更新日期：1999-07-06 00:00:00

abstract：:Fibrinogen binding to receptors on stimulated platelets is a prerequisite for platelet aggregation. To gain further insight into the role of fibrinogen in platelet aggregation and to identify the platelet fibrinogen receptor, we developed a monoclonal anti-platelet antibody that inhibited platelet aggregation. The pur...

journal_title：Proceedings of the National Academy of Sciences of the United States of America

authors： Bennett JS,Hoxie JA,Leitman SF,Vilaire G,Cines DB

更新日期：1983-05-01 00:00:00

abstract：:Both ghrelin and somatostatin (SST) inhibit glucose-stimulated insulin secretion (GSIS) from pancreatic β-cells, but how these independent actions are regulated has been unclear. The mechanism must accommodate noncanonical ghrelin receptor (GHS-R1a)-G-protein coupling to Gα(i/o) instead of Gα(q11) and dependence on en...

journal_title：Proceedings of the National Academy of Sciences of the United States of America

authors： Park S,Jiang H,Zhang H,Smith RG

更新日期：2012-11-13 00:00:00

abstract：:Monoclonal antibodies against the porcine 1,25-dihydroxyvitamin D3 receptor were immobilized on Sepharose CL-4B and used to obtain a highly purified 1,25-dihydroxyvitamin D3 receptor fraction with a 45% recovery of the 1,25-dihydroxyvitamin D3 binding capacity. The porcine receptor was purified to homogeneity by prepa...

journal_title：Proceedings of the National Academy of Sciences of the United States of America

authors： Brown TA,Prahl JM,DeLuca HF

更新日期：1988-04-01 00:00:00

abstract：:Biochemically, the syntrophic bacteria constitute the missing link in our understanding of anaerobic flow of carbon in the biosphere. The completed genome sequence of Syntrophus aciditrophicus SB, a model fatty acid- and aromatic acid-degrading syntrophic bacterium, provides a glimpse of the composition and architectu...

journal_title：Proceedings of the National Academy of Sciences of the United States of America

authors： McInerney MJ,Rohlin L,Mouttaki H,Kim U,Krupp RS,Rios-Hernandez L,Sieber J,Struchtemeyer CG,Bhattacharyya A,Campbell JW,Gunsalus RP

更新日期：2007-05-01 00:00:00

abstract：:The developmental plasticity of plants relies on the remarkable ability of the meristems to integrate nutrient and energy availability with environmental signals. Meristems in root and shoot apexes share highly similar molecular players but are spatially separated by soil. Whether and how these two meristematic tissue...

journal_title：Proceedings of the National Academy of Sciences of the United States of America

authors： Li X,Cai W,Liu Y,Li H,Fu L,Liu Z,Xu L,Liu H,Xu T,Xiong Y

更新日期：2017-03-07 00:00:00

abstract：:Exposure of 3T3/A31 cells to serum-free medium, one type of apoptotic stimulus, causes a rapid increase in the sphingosine (Sph) level, which initiates a series of processes: (i) activation of caspase 3 through an enhanced "cascade" of caspases, (ii) release of the C-terminal-half kinase domain of PKCdelta (PKCdelta K...

journal_title：Proceedings of the National Academy of Sciences of the United States of America

authors： Suzuki E,Handa K,Toledo MS,Hakomori S

更新日期：2004-10-12 00:00:00

abstract：:Cyclophilins are a family of ubiquitous proteins that are the intracellular target of the immunosuppressant drug cyclosporin A. Although cyclophilins catalyze peptidylprolyl cis-trans isomerization in vitro, it has remained open whether they also perform this function in vivo. Here we show that Cpr3p, a cyclophilin in...

journal_title：Proceedings of the National Academy of Sciences of the United States of America

authors： Matouschek A,Rospert S,Schmid K,Glick BS,Schatz G

更新日期：1995-07-03 00:00:00

abstract：:The Japanese firefly squid, Watasenia scintillans, emits intense flashes of light from three tiny luminous organs that are located at the tip of each of a pair of ventral arms. Light is also produced from hundreds of other minute organs that are scattered over the body. The luminescence is due to an ATP-dependent reac...

journal_title：Proceedings of the National Academy of Sciences of the United States of America

authors： Tsuji FI

更新日期：1985-07-01 00:00:00

abstract：:The E26 transformation-specific (Ets-1) transcription factor is autoinhibited by a conformationally disordered serine-rich region (SRR) that transiently interacts with its DNA-binding ETS domain. In response to calcium signaling, autoinhibition is reinforced by calmodulin-dependent kinase II phosphorylation of serines...

journal_title：Proceedings of the National Academy of Sciences of the United States of America

authors： Desjardins G,Meeker CA,Bhachech N,Currie SL,Okon M,Graves BJ,McIntosh LP

更新日期：2014-07-29 00:00:00

abstract：:Histone methylation has an important role in transcriptional regulation. However, unlike H3K4 and H3K9 methylation, the role of H4K20 monomethylation (H4K20me-1) in transcriptional regulation remains unclear. Here, we show that Wnt3a specifically stimulates H4K20 monomethylation at the T cell factor (TCF)-binding elem...

journal_title：Proceedings of the National Academy of Sciences of the United States of America

authors： Li Z,Nie F,Wang S,Li L

更新日期：2011-02-22 00:00:00

abstract：:Signal transducer and activator of transcription 3 (STAT3) is a multifunctional protein that participates in signaling pathways initiated by various growth factors and cytokines. It exists in multiple forms including those phosphorylated on Tyr(705) (pYSTAT3) or Ser(727) (pSSTAT3) as well as the unphosphorylated prote...

journal_title：Proceedings of the National Academy of Sciences of the United States of America

authors： Koo MY,Park J,Lim JM,Joo SY,Shin SP,Shim HB,Chung J,Kang D,Woo HA,Rhee SG

更新日期：2014-04-29 00:00:00

abstract：:A 92-amino acid polypeptide, alpha-inhibin-92 (alpha-IB-92), has been isolated and characterized from human seminal plasma and found to be active in suppressing follicle-stimulating hormone (FSH) release in vitro. In the present in vivo study, intravenous injection of synthetic alpha-IB-92 (4 and 20 micrograms) signif...

journal_title：Proceedings of the National Academy of Sciences of the United States of America

authors： Yu WH,McCann SM,Li CH

更新日期：1988-01-01 00:00:00

abstract：:Archaea (archaebacteria) are a phenotypically diverse group of microorganisms that share a common evolutionary history. There are four general phenotypic groups of archaea: the methanogens, the extreme halophiles, the sulfate-reducing archaea, and the extreme thermophiles. In the marine environment, archaeal habitats ...

journal_title：Proceedings of the National Academy of Sciences of the United States of America

authors： DeLong EF

更新日期：1992-06-15 00:00:00

abstract：:Mechanism of enzymatic conversion of a fatty acid to the corresponding alkane by the loss of the carboxyl carbon was investigated with particulate preparations from Pisum sativum. A heavy particulate preparation (sp. gr., 1.30 g/cm3) isolated by two density-gradient centrifugation steps catalyzed conversion of octadec...

journal_title：Proceedings of the National Academy of Sciences of the United States of America

authors： Cheesbrough TM,Kolattukudy PE

更新日期：1984-11-01 00:00:00

abstract：:The plant hormone abscisic acid (ABA) is produced in response to abiotic stresses and mediates stomatal closure in response to drought via recently identified ABA receptors (pyrabactin resistance/regulatory component of ABA receptor; PYR/RCAR). SLAC1 encodes a central guard cell S-type anion channel that mediates ABA-...

journal_title：Proceedings of the National Academy of Sciences of the United States of America

authors： Brandt B,Brodsky DE,Xue S,Negi J,Iba K,Kangasjärvi J,Ghassemian M,Stephan AB,Hu H,Schroeder JI

更新日期：2012-06-26 00:00:00

abstract：:WE REEXAMINED TWO QUESTIONS CONCERNING LYT ANTIGENS OF CYTOTOXIC T CELLS OF THE MOUSE: is Lyt-1 antigen expressed on cytotoxic effector cells and can cytotoxicity be blocked by antibody to Lyt antigens in the absence of added complement? A 3-hr (51)Cr-release assay with splenic effector cells and leukemia or myeloma t...

journal_title：Proceedings of the National Academy of Sciences of the United States of America

authors： Nakayama E,Shiku H,Stockert E,Oettgen HF,Old LJ

更新日期：1979-04-01 00:00:00

abstract：:Cyanobacteria, blue-green algae, are the most abundant autotrophs in aquatic environments and form the base of all aquatic food chains by fixing carbon and nitrogen into cellular biomass. The single most important nutrient for photosynthesis and growth is nitrate, which is severely limiting in many aquatic environment...

journal_title：Proceedings of the National Academy of Sciences of the United States of America

authors： Koropatkin NM,Pakrasi HB,Smith TJ

更新日期：2006-06-27 00:00:00

abstract：:Serotonin (5-HT) plays a key role in early brain development, and manipulation of 5-HT levels during this period can have lasting neurobiological and behavioral consequences. It is unclear how perinatal exposure to drugs, such as selective serotonin reuptake inhibitors (SSRIs), impacts cortical neural network function...

journal_title：Proceedings of the National Academy of Sciences of the United States of America

authors： Simpson KL,Weaver KJ,de Villers-Sidani E,Lu JY,Cai Z,Pang Y,Rodriguez-Porcel F,Paul IA,Merzenich M,Lin RC

更新日期：2011-11-08 00:00:00

abstract：:The decrease with age of the adrenal-secreted dehydroepiandrosterone sulfate (DHEAS) in serum has suggested that it may be causally related to longevity. For the PAQUID [People (Personnes) Aged (Agées) About What (Quid, in Latin)] cohort of elderly subjects, we have previously reported higher DHEAS in men than in wome...

journal_title：Proceedings of the National Academy of Sciences of the United States of America

authors： Mazat L,Lafont S,Berr C,Debuire B,Tessier JF,Dartigues JF,Baulieu EE

更新日期：2001-07-03 00:00:00

abstract：:The nonlinear nature of integration among cortical brain areas renders the effective connectivity between them inherently dynamic and context-sensitive. One emerging architectural principle of functional brain organization, which rests explicitly on these nonlinear interactions, is that neuronal responses expressed at...

journal_title：Proceedings of the National Academy of Sciences of the United States of America

authors： Friston KJ,Büchel C

更新日期：2000-06-20 00:00:00

abstract：:Mind wandering represents the human capacity for internally focused thought and relies upon the brain's default network and its interactions with attentional networks. Studies have characterized mind wandering in healthy people, yet there is limited understanding of how this capacity is affected in clinical population...

journal_title：Proceedings of the National Academy of Sciences of the United States of America

authors： O'Callaghan C,Shine JM,Hodges JR,Andrews-Hanna JR,Irish M

更新日期：2019-02-19 00:00:00

abstract：:Tumor hypoxia and the hypoxia-inducible factors (HIFs) play a central role in the development of cancer. To study the relationship between tumor growth, tumor hypoxia, the stabilization of HIF-1alpha, and HIF transcriptional activity, we have established an in vivo imaging tool that allows longitudinal and noninvasive...

journal_title：Proceedings of the National Academy of Sciences of the United States of America

authors： Lehmann S,Stiehl DP,Honer M,Dominietto M,Keist R,Kotevic I,Wollenick K,Ametamey S,Wenger RH,Rudin M

更新日期：2009-08-18 00:00:00

abstract：:The kinetics of charge transfer depend crucially on the dielectric reorganization of the medium. In enzymatic reactions that involve charge transfer, atomic dielectric response of the active site and of its surroundings determines the efficiency of the protein as a catalyst. We report direct spectroscopic measurements...

journal_title：Proceedings of the National Academy of Sciences of the United States of America

authors： Mertz EL,Krishtalik LI

更新日期：2000-02-29 00:00:00

abstract：:Sex determination in mammals is governed by antagonistic interactions of two genetic pathways, imbalance in which may lead to disorders/differences of sex development (DSD) in human. Among 46,XX individuals with testicular DSD (TDSD) or ovotesticular DSD (OTDSD), testicular tissue is present in the gonad. Although the...

journal_title：Proceedings of the National Academy of Sciences of the United States of America

authors： Eozenou C,Gonen N,Touzon MS,Jorgensen A,Yatsenko SA,Fusee L,Kamel AK,Gellen B,Guercio G,Singh P,Witchel S,Berman AJ,Mainpal R,Totonchi M,Mohseni Meybodi A,Askari M,Merel-Chali T,Bignon-Topalovic J,Migale R,Costanzo

更新日期：2020-06-16 00:00:00