Página 1 dos resultados de 10 itens digitais encontrados em 0.005 segundos

The bldC Developmental Locus of Streptomyces coelicolor Encodes a Member of a Family of Small DNA-Binding Proteins Related to the DNA-Binding Domains of the MerR Family

Hunt, Alison C.; Servín-González, Luis; Kelemen, Gabriella H.; Buttner, Mark J.
Fonte: American Society for Microbiology Publicador: American Society for Microbiology
Tipo: Artigo de Revista Científica
Publicado em /01/2005 Português
Relevância na Pesquisa
26.88851%
The bldC locus, required for formation of aerial hyphae in Streptomyces coelicolor, was localized by map-based cloning to the overlap between cosmids D17 and D25 of a minimal ordered library. Subcloning and sequencing showed that bldC encodes a member of a previously unrecognized family of small (58- to 78-residue) DNA-binding proteins, related to the DNA-binding domains of the MerR family of transcriptional activators. BldC family members are found in a wide range of gram-positive and gram-negative bacteria. Constructed ΔbldC mutants were defective in differentiation and antibiotic production. They failed to form an aerial mycelium on minimal medium and showed severe delays in aerial mycelium formation on rich medium. In addition, they failed to produce the polyketide antibiotic actinorhodin, and bldC was shown to be required for normal and sustained transcription of the pathway-specific activator gene actII-orf4. Although ΔbldC mutants produced the tripyrrole antibiotic undecylprodigiosin, transcripts of the pathway-specific activator gene (redD) were reduced to almost undetectable levels after 48 h in the bldC mutant, in contrast to the bldC+ parent strain in which redD transcription continued during aerial mycelium formation and sporulation. This suggests that bldC may be required for maintenance of redD transcription during differentiation. bldC is expressed from a single promoter. S1 nuclease protection assays and immunoblotting showed that bldC is constitutively expressed and that transcription of bldC does not depend on any of the other known bld genes. The bldC18 mutation that originally defined the locus causes a Y49C substitution that results in instability of the protein.

Infrared spectroscopic investigations of pulmonary surfactant. Surface film transitions at the air-water interface and bulk phase thermotropism.

Dluhy, R. A.; Reilly, K. E.; Hunt, R. D.; Mitchell, M. L.; Mautone, A. J.; Mendelsohn, R.
Fonte: The Biophysical Society Publicador: The Biophysical Society
Tipo: Artigo de Revista Científica
Publicado em /12/1989 Português
Relevância na Pesquisa
26.88851%
The molecular structure of the phospholipid component of intact pulmonary surfactant isolated from bovine lung lavage has been examined by Fourier transform infrared spectroscopy. Two different physical states of the surfactant were examined by means of different infrared spectroscopic sampling techniques. Transmission infrared experiments were used to study the surfactant in the bulk phase. In these experiments, the thermotropic behavior of the bulk surfactant was monitored by temperature-induced variations in the phospholipid acyl chain CH2 stretching frequencies. A broad phase transition (confirmed by differential scanning calorimetry) was noted with an onset temperature near 15 degrees C and a completion temperature near 42 degrees C. In addition to the bulk transmission experiments, external reflection infrared spectroscopy was used to examine surfactant films in situ at the air-water interface. As surface pressure was increased from 0 to 43 dyn/cm, a gradual and continuous decrease in the CH2 stretching frequency was noted for the surfactant. Thus, under surface pressures which correspond to large lung volumes in vivo, the surfactant acyl chains exist mostly in the ordered (trans) configuration. The frequency shift in the CH2 stretching mode is consistent with a continuous ordering of the acyl chains upon compression over the pressure range 0-43 dyn/cm...

Solution Structure of the NaV1.2 C-terminal EF-hand Domain*S⃞

Miloushev, Vesselin Z.; Levine, Joshua A.; Arbing, Mark A.; Hunt, John F.; Pitt, Geoffrey S.; Palmer, Arthur G.
Fonte: American Society for Biochemistry and Molecular Biology Publicador: American Society for Biochemistry and Molecular Biology
Tipo: Artigo de Revista Científica
Publicado em 06/03/2009 Português
Relevância na Pesquisa
26.88851%
Voltage-gated sodium channels initiate the rapid upstroke of action potentials in many excitable tissues. Mutations within intracellular C-terminal sequences of specific channels underlie a diverse set of channelopathies, including cardiac arrhythmias and epilepsy syndromes. The three-dimensional structure of the C-terminal residues 1777-1882 of the human NaV1.2 voltage-gated sodium channel has been determined in solution by NMR spectroscopy at pH 7.4 and 290.5 K. The ordered structure extends from residues Leu-1790 to Glu-1868 and is composed of four α-helices separated by two short anti-parallel β-strands; a less well defined helical region extends from residue Ser-1869 to Arg-1882, and a disordered N-terminal region encompasses residues 1777-1789. Although the structure has the overall architecture of a paired EF-hand domain, the NaV1.2 C-terminal domain does not bind Ca2+ through the canonical EF-hand loops, as evidenced by monitoring 1H,15N chemical shifts during aCa2+ titration. Backbone chemical shift resonance assignments and Ca2+ titration also were performed for the NaV1.5 (1773-1878) isoform, demonstrating similar secondary structure architecture and the absence of Ca2+ binding by the EF-hand loops. Clinically significant mutations identified in the C-terminal region of NaV1 sodium channels cluster in the helix I-IV interface and the helix II-III interhelical segment or in helices III and IV of the NaV1.2 (1777-1882) structure.

Factor Relationships of Metabolic Syndrome and Echocardiographic Phenotypes in the HyperGEN Study

Huang, Pinchia; Kraja, Aldi T.; Tang, Weihong; Hunt, Steven C.; North, Kari E.; Lewis, Cora E.; Devereux, Richard B.; de Simone, Giovanni; Arnett, Donna K.; Rice, Treva; Rao, D.C.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /07/2008 Português
Relevância na Pesquisa
26.88851%
Metabolic Syndrome (MetS) and its risk factors are predictors of cardiovascular events. MetS is also directly associated with echocardiographic (ECHO) phenotypes. The current study is the first to investigate factors associated with both MetS risk factors and echocardiographic phenotypes and to assess their heritability. Multivariate factor analysis (FA) was performed on 15 traits in 1,393 African Americans and 1,133 Caucasians, as well as stratified by type 2 diabetes mellitus (DM) status. FA with Varimax rotation established four to five latent factors across ethnicities and DM stratifications. Among MetS risk factors, BP was most highly correlated with cardiac traits. The factor domains, ordered by the proportion of variance explained, were “LV wall thickness,” “LV geometry,” “BP,” “body mass index-insulin,” and “lipid-insulin.” FA without any rotation identified special (cross domain) MetS-ECHO factors, “BP-LV geometry” and “BP-LV dimension-wall thickness” in Caucasians. Of the total original risk factors variance, 50%–57% of it was explained by the latent factors. Heritabilities were highest for body mass index-insulin (37–53%), lowest for “BP” factors (15–27%) and intermediate for MetS-ECHO factors. These identified latent factors can be utilized as summary phenotypes in epidemiological...

Snapshots of Dynamics in Synthesizing N6-isopentenyladenosine at tRNA Anticodon†,‡

Chimnaronk, Sarin; Forouhar, Farhad; Sakai, Junichi; Yao, Min; Tron, Cecile M.; Atta, Mohamed; Fontecave, Marc; Hunt, John F.; Tanaka, Isao
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em 16/06/2009 Português
Relevância na Pesquisa
26.88851%
Bacterial and eukaryotic transfer RNAs that decode codons starting with uridine have a hydrophobically-hypermodified adenosine at the position 37 (A37) adjacent to the 3′-end of the anticodon, which is essential for efficient and highly accurate protein translation by the ribosome. However, it remains unclear how the corresponding tRNAs are selected to be modified by alkylation at the correct position of the adenosine base. We have determined a series of the crystal structures of bacterial tRNA isopentenyltransferase (MiaA) in apo- and tRNA-bound forms, which completely render snapshots of substrate selections during modification of RNA. A compact evolutionary inserted domain (herein ‘swinging domain’) in MiaA that exhibits as a highly mobile entity moves around the catalytic domain as likely to reach and trap the tRNA substrate. Thereby, MiaA clamps the anticodon stem loop of tRNA substrate between the catalytic and swinging domains, where the two conserved elongated residues from the swinging domain pinch the two flanking A36 and A38 together to squeeze out A37 into the reaction tunnel. The site-specific isopentenylation of RNA is thus ensured by a characteristic pinch-and-flip mechanism and by a reaction tunnel to confine the substrate selection. Furthermore...

Analysis of churn and excess material at the Pearl Harbor Naval Shipyard

Cheshure, Kevin; Hunt, Anthony; Bangert, Lawrence; Cheshure, Kevin
Fonte: Monterey, California. Naval Postgraduate School Publicador: Monterey, California. Naval Postgraduate School
Formato: xii, 30 p : ill. (some col.) ; 28 cm.
Português
Relevância na Pesquisa
27.481914%
MBA Professional Report; Approved for public release; distribution is unlimited.; MBA Professional Report; Approved for public release; distribution is unlimited.; For a Naval Shipyard, the amount of material ordered after beginning an availability (churn) and the amount of material ordered but not used (excess) are key performance indicators. Pearl Harbor Naval Shipyard's metrics indicate that an average of 50% of material ordered during an availability is ordered after the start of the availability and that 15% of material is excess. The NAVSEA goal for both metrics is 5%. We investigate the causes of high rates of material churn and excess at Pearl Harbor Naval Shipyard and provide recommendations for reducing them.; Lieutenant Commander, United States Navy; Lieutenant Commander, United States Navy; Lieutenant, United States Naval Reserve; Lieutenant Commander, United States Navy; Lieutenant Commander, United States Navy; Lieutenant, United States Naval Reserve

Selfishness, fraternity, and other-regarding preference in spatial evolutionary games

Szabo, Gyorgy; Szolnoki, Attila
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 22/03/2011 Português
Relevância na Pesquisa
16.888511%
Spatial evolutionary games are studied with myopic players whose payoff interest, as a personal character, is tuned from selfishness to other-regarding preference via fraternity. The players are located on a square lattice and collect income from symmetric two-person two-strategy (called cooperation and defection) games with their nearest neighbors. During the elementary steps of evolution a randomly chosen player modifies her strategy in order to maximize stochastically her utility function composed from her own and the co-players' income with weight factors $1-Q$ and Q. These models are studied within a wide range of payoff parameters using Monte Carlo simulations for noisy strategy updates and by spatial stability analysis in the low noise limit. For fraternal players ($Q=1/2$) the system evolves into ordered arrangements of strategies in the low noise limit in a way providing optimum payoff for the whole society. Dominance of defectors, representing the "tragedy of the commons", is found within the regions of prisoner's dilemma and stag hunt game for selfish players (Q=0). Due to the symmetry in the effective utility function the system exhibits similar behavior even for Q=1 that can be interpreted as the "lovers' dilemma".; Comment: 7 two-column pages...

Glassy Slowing of Stripe Modulation in (La,Eu,Nd)(2-x)(Sr,Ba)(x)CuO4: A Cu-63 and La-139 NQR Study Down to 350mK

Hunt, A. W.; Singer, P. M.; Cederstrom, A. F.; Imai, T.
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
26.88851%
We report a comprehensive Cu and La NQR study down to 350mK in the stripe phase of the hole-doped high temperature superconductors with hole concentration approximately 1/8. We observe the hyperfine broadened NQR lineshape only below 8-20K for x=1/8, indicating that the ordered moments continue to fluctuate slowly even below the temperature range where they appear static in other measurements. Detailed numerical simulations of the Zeeman perturbed Cu NQR lineshape establish that widely accepted models of periodic modulation of spin density waves with maximum moment approxiamtely 0.3mu_B can not account for the NQR lineshape. These results suggest that significant disorder exists at NQR time scales. By fitting a single model to several sets of experimental data, we deduce the spatial distribution of the spin fluctuation frequency scale and its temperature dependence. Our results indicate that as soon as charge dynamics slow down, the spin fluctuationsbegin to slow dramatically with spin stiffness approximately 200K. However, the motional narrowing feature observed in the Zeeman perturbed NQR measurements suggest that the slowing of the spin fluctuations levels off at frequencies somewhat below the NQR frequency. By extending the analysis to other hole concentrations...

Messersmith, G.S., Vienna. To William Phillips, Washington.

Messersmith, George S. (George Strausser), 1883-1960.
Fonte: Special Collections, University of Delaware Library Publicador: Special Collections, University of Delaware Library
Tipo: Outros Formato: Typed Letter Copy, 13 p.
Português
Relevância na Pesquisa
16.888511%
Situation quiet in Austria; less organized opposition to Government; Socialists and Communists lack leadership; Austrian social insurance system in serious difficulty; may be necessary to reduce payments, to increase taxes, or put budget out of balance; Austrian Nazis disorganized and leaders discouraged; no prospect of more money from Germany; further blows to Austrian Nazis were [Fritz von] Tschirschky incident and dissolution of Nazi organization in Upper Austria; von Tschirschky [und Boegendorff], special attach?? at German Legation, no Nazi and open in his criticism of Nazi policy, was instructed to return to Berlin; instead he went to Switzerland, where his family is expected to join him; [Franz] von Papen ordered to hunt von Tschirschky and see that he return to Berlin; von Tschirschky had contact with Austrian Legitimists; he favored return of Hohenzollerns in Germany; execution in Germany of two women [Baroness Benita von Falkenhayn and Frau Renate von Natzmer] as "spies" has not helped Nazi cause; believes visit of Chancellor and Foreign Minister to Paris and London has given them increased confidence; both were prepared to talk about Hapsburg question; Schuschnigg a fine man, but does not like his job, and like most of the men in his government...

Ordered Hunt Schemes for Overlaid CDMA Cellular Systems

Castañeda-Camacho,J.; Lara-Rodríguez,D.
Fonte: Facultad de Ingeniería, UNAM Publicador: Facultad de Ingeniería, UNAM
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/09/2010 Português
Relevância na Pesquisa
67.96766%
The CDMA overlay concept, has been proposed as one alternative to take advantage of the bandwidth available in narrowband systems. In fact, the basic idea of the CDMA overlay is to allow to wideband CDMA wave forms, to share a common spectrum with narrowband conventional wave forms. In this work, we have focused in the analysis of the performance of the forward link of the CDMA and TDMA systems when they are overlaid. In our model, in order to limit the interference into the CDMA layer caused by the TDMA system, the use of notch filters has been considered. However, one drawback of the filters is that it rejects only one part of the interference generated by the TDMA system. Therefore, we have proposed two new ideas of reduction of the interference which can not be eliminated by filters; ordered hunt and real location of the slots. Finally, we present an analytical evaluation of the forward link capacity of the systems involved in the overlaid process, due to this is the limiting link and as a function of the outage probabilities. Practical considerations such as power requirements, power control, handoff, the offered load for different services and scenarios are also addressed.