Determinants of lemming outbreaks.

abstract：:Banded iron formations (BIFs) record a time of extensive Fe deposition in the Precambrian oceans, but the sources and pathways for metals in BIFs remain controversial. Here, we present Fe- and Nd-isotope data that indicate two sources of Fe for the large BIF units deposited 2.5 billion y ago. High-εNd and -δ(56)Fe sig...

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

authors： Li W,Beard BL,Johnson CM

更新日期：2015-07-07 00:00:00

abstract：:Individual organisms are complex in a special way. The organization and function of their parts seem directed toward a purpose: the survival and reproduction of that individual. Groups of organisms are different. They may also be complex, but that is usually because their parts, the individual organisms, are working a...

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

authors： Strassmann JE,Queller DC

更新日期：2007-05-15 00:00:00

abstract：:We describe a fractionation and purification scheme for the Drosophila RNA polymerase II general transcription factors. Drosophila TFIIE, TFIIF, TFIIH, and RNA polymerase II have been purified to greater than 50% homogeneity from Drosophila embryo nuclear extracts. TFIID has been purified 80-fold and is not significan...

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

authors： Austin RJ,Biggin MD

更新日期：1996-06-11 00:00:00

abstract：:The evolutionary process that occurs when a species colonizes a new environment provides an opportunity to explore the mechanisms underlying genetic adaptation, which is essential knowledge for understanding evolution and the maintenance of biodiversity. Atlantic herring has an estimated total breeding stock of about ...

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

authors： Hill J,Enbody ED,Pettersson ME,Sprehn CG,Bekkevold D,Folkvord A,Laikre L,Kleinau G,Scheerer P,Andersson L

更新日期：2019-09-10 00:00:00

abstract：:Allergies are highly prevalent, and allergic responses can be triggered even in the absence of allergens due to Pavlovian conditioning to a specific cue. Here we show in humans suffering from allergic rhinitis that merely reencountering the environmental context in which an allergen was administered a week earlier is ...

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

authors： Besedovsky L,Benischke M,Fischer J,Yazdi AS,Born J

更新日期：2020-05-19 00:00:00

abstract：:Abnormal tubulofilamentous structures have been identified in electron micrographs of thin sections and negatively stained impression grids prepared from brains of animals with scrapie and other spongiform encephalopathies, and we showed that such tubules contain a core of filamentous structures resembling scrapie-ass...

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

authors： Narang HK,Asher DM,Gajdusek DC

更新日期：1988-05-01 00:00:00

abstract：:A cell of the bacterium Escherichia coli was tethered covalently to a glass coverslip by a single flagellum, and its rotation was stopped by using optical tweezers. The tweezers acted directly on the cell body or indirectly, via a trapped polystyrene bead. The torque generated by the flagellar motor was determined by ...

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

authors： Berry RM,Berg HC

更新日期：1997-12-23 00:00:00

abstract：:Direct conversion of carbon dioxide to multicarbon products remains as a grand challenge in electrochemical CO2 reduction. Various forms of oxidized copper have been demonstrated as electrocatalysts that still require large overpotentials. Here, we show that an ensemble of Cu nanoparticles (NPs) enables selective form...

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

authors： Kim D,Kley CS,Li Y,Yang P

更新日期：2017-10-03 00:00:00

abstract：:Estimates of relative rates of molecular evolution from a DNA-hybridization phylogeny for 26 hummingbird species provide evidence for a negative association between elevation and rate of single-copy genome evolution. This effect of elevation on rate remains significant even after taking into account a significant nega...

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

authors： Bleiweiss R

更新日期：1998-01-20 00:00:00

abstract：:Germinal centers (GCs) are specialized microenvironments in secondary lymphoid organs where high-affinity antibody-producing B cells are selected based on B-cell antigen receptor (BCR) signal strength. BCR signaling required for normal GC selection is uncertain. We have found that protein kinase N1 (PKN1, also known a...

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

authors： Yasui T,Sakakibara-Yada K,Nishimura T,Morita K,Tada S,Mosialos G,Kieff E,Kikutani H

更新日期：2012-12-18 00:00:00

abstract：:Peritoneal macrophages were obtained from DBA/2 mice that were untreated or after the injection of bacillus Calmette-Guerin (BCG), thioglycollate broth, proteose-peptone broth, or gamma-irradiated P-815 tumor cells. These macrophages were "activated" to become cytotoxic for a fibroblast cell line (L 929) by the additi...

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

authors： Blumenthal EJ,Roberts WK,Vasil A,Talmage DW

更新日期：1983-04-01 00:00:00

abstract：:The human renin gene was isolated from a Charon 4A human genomic library and characterized. The gene spans about 11.7 kilobases and consists of 10 exons and 9 introns that map at points that could be variable surface loops of the enzyme. The complete coding regions, the 5'- and 3'-flanking regions, and the exon-intron...

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

authors： Miyazaki H,Fukamizu A,Hirose S,Hayashi T,Hori H,Ohkubo H,Nakanishi S,Murakami K

更新日期：1984-10-01 00:00:00

abstract：:Chromatin boundaries or insulators modulate enhancer-promoter interactions in complex genetic loci. However, the mechanism underlying insulator activity is not known. Previous studies showed that the activity of the Drosophila suHw insulator is abolished by the tandem arrangement (pairing) of the insulator elements, s...

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

authors： Majumder P,Cai HN

更新日期：2003-04-29 00:00:00

abstract：:In this study, we compared the transport of newly synthesized cholesterol with that of influenza virus hemagglutinin (HA) from the endoplasmic reticulum to the plasma membrane. The arrival of cholesterol on the cell surface was monitored by cyclodextrin removal, and HA transport was monitored by surface trypsinization...

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

authors： Heino S,Lusa S,Somerharju P,Ehnholm C,Olkkonen VM,Ikonen E

更新日期：2000-07-18 00:00:00

abstract：:The dissociation and association of an immobilized preparation of the octameric enzyme porphobilinogen synthase [5-aminolevulinate hydro-lyase (adding 5-aminolevulinate and cyclizing), EC 4.2.1.24] is described. On treatment of the immobilized preparation with 4 M urea, four subunits per octamer are removed which can ...

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

authors： Gurne D,Chen J,Shemin D

更新日期：1977-04-01 00:00:00

abstract：:The role of the cerebellar cortex in motor learning was investigated by comparing the paramedian lobule of adult rats given difficult acrobatic training to that of rats that had been given extensive physical exercise or had been inactive. The paramedian lobule is activated during limb movements used in both acrobatic ...

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

authors： Black JE,Isaacs KR,Anderson BJ,Alcantara AA,Greenough WT

更新日期：1990-07-01 00:00:00

abstract：:The type-III secretion (T3S) systems of bacteria are part of self-assembling nanomachines: the bacterial flagellum that enables cells to propel themselves through liquid and across hydrated surfaces, and the injectisome that delivers pathogenic effector proteins into eukaryotic host cells. Although the flagellum and i...

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

authors： Wee DH,Hughes KT

更新日期：2015-03-31 00:00:00

abstract：:Human neutrophils respond to chemoattractants, resulting in their accumulation at an inflammatory site. Chemoattractants such as the C5a peptide, derived from the C5 complement factor, bind to inhibitory guanine nucleotide binding protein (Gi)-coupled seven membrane-spanning receptors expressed in neutrophils. C5a rec...

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

authors： Buhl AM,Avdi N,Worthen GS,Johnson GL

更新日期：1994-09-13 00:00:00

abstract：:Zinniol [1,2-bis(hydroxymethyl)-3-methoxy-4-methyl-5-(3-methyl-2-butenyloxy)benzene], a toxin produced by fungi of the Alternaria group, causes symptoms in plants that resemble those induced by the fungi. The phytotoxin binds to carrot protoplasts and isolated membranes in a saturable and reversible manner. Receptor o...

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

authors： Thuleau P,Graziana A,Rossignol M,Kauss H,Auriol P,Ranjeva R

更新日期：1988-08-01 00:00:00

abstract：:Mutations at position 187 in secreted gelsolin enable aberrant proteolysis at the 172-173 and 243-244 amide bonds, affording the 71-residue amyloidogenic peptide deposited in Familial Amyloidosis of Finnish Type (FAF). Thermodynamic comparisons of two different domain 2 constructs were carried out to study possible ef...

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

authors： Ratnaswamy G,Huff ME,Su AI,Rion S,Kelly JW

更新日期：2001-02-27 00:00:00

abstract：:CooA, the CO-sensing heme protein from Rhodospirillum rubrum, regulates the expression of genes that encode a CO-oxidation system, allowing R. rubrum to use CO as a sole energy source. To better understand the gas-sensing regulation mechanism used by R. rubrum CooA and its homologs in other organisms, we characterized...

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

authors： Clark RW,Lanz ND,Lee AJ,Kerby RL,Roberts GP,Burstyn JN

更新日期：2006-01-24 00:00:00

abstract：:Spinach chloroplasts were found to contain three forms of cytochrome b(559) that have the same alpha-peak at 559 nm, but are distinguished from one another by their oxidation-reduction potentials. The high-potential (H) form (E(m) about 330-350 mV) is reducible by hydroquinone, the middle-potential (M) form (E(m) abou...

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

authors： Wada K,Arnon DI

更新日期：1971-12-01 00:00:00

abstract：:The structures of the major folding intermediate, the transition state for folding, and the folded state of barnase have been previously characterized. We now add a further step toward a complete picture of the folding of barnase by reporting the backbone 15N, 13C, and 1H NMR assignments for barnase unfolded at pH 1.8...

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

authors： Arcus VL,Vuilleumier S,Freund SM,Bycroft M,Fersht AR

更新日期：1994-09-27 00:00:00

abstract：:Leptin acts as a potent inhibitory factor against obesity by regulating energy expenditure, food intake, and adiposity. The obese diabetic db/db mouse, which has defects in leptin receptor, displays enhanced neural responses and elevated behavioral preference to sweet stimuli. Here, we show the effects of leptin on th...

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

authors： Kawai K,Sugimoto K,Nakashima K,Miura H,Ninomiya Y

更新日期：2000-09-26 00:00:00

abstract：:In this note the Weierstrass integral J is taken as L, the Riemann integral of length. Here M(n), n > 1, is a compact, connected manifold of class C(infinity) with a positive definite Riemann structure. Presentations (phi, U(phi)) in M(n) and geodesics (with the aid of the Euler-Riemann equations) are defined in Morse...

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

authors： Morse M

更新日期：1977-06-01 00:00:00

abstract：:MuB is an ATP-dependent nonspecific DNA-binding protein that regulates the activity of the MuA transposase and captures target DNA for transposition. Mechanistic understanding of MuB function has previously been hindered by MuB's poor solubility. Here we combine bioinformatic, mutagenic, biochemical, and electron micr...

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

authors： Mizuno N,Dramićanin M,Mizuuchi M,Adam J,Wang Y,Han YW,Yang W,Steven AC,Mizuuchi K,Ramón-Maiques S

更新日期：2013-07-02 00:00:00

abstract：:Kss1, a yeast mitogen-activated protein kinase (MAPK), in its unphosphorylated (unactivated) state binds directly to and represses Ste12, a transcription factor necessary for expression of genes whose promoters contain filamentous response elements (FREs) and genes whose promoters contain pheromone response elements (...

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

authors： Bardwell L,Cook JG,Zhu-Shimoni JX,Voora D,Thorner J

更新日期：1998-12-22 00:00:00

abstract：:The cytokines interleukin (IL) 4 and IL-13 induce many of the same biological responses, including class switching to IgE and induction of major histocompatibility complex class II antigens and CD23 on human B cells. It has recently been shown that IL-4 induces the tyrosine phosphorylation of a 170-kDa protein, a subs...

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

authors： Keegan AD,Johnston JA,Tortolani PJ,McReynolds LJ,Kinzer C,O'Shea JJ,Paul WE

更新日期：1995-08-15 00:00:00

abstract：:A calmodulin-neomycin-resistance fusion gene was introduced into Trypanosoma brucei by electroporation, and stably transformed cell lines were obtained. In all of the transformants, the fusion gene had integrated into the host genome at the cognate locus, evidently by homologous recombination within flanking calmoduli...

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

authors： Eid J,Sollner-Webb B

更新日期：1991-03-15 00:00:00

abstract：:The serum thymic factor (FTS) utilized in its synthetic or natural form loses its biological activity in a rosette assay after treatment with a metal ion-chelating agent, Chelex 100. This activity is restored by the addition of Zn salts and, to a lesser extent, certain other metal salts. FTS activation is secondary to...

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

authors： Dardenne M,Pléau JM,Nabarra B,Lefrancier P,Derrien M,Choay J,Bach JF

更新日期：1982-09-01 00:00:00