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Sample records for 4fe-4s clusters fa

  1. Formation of [4Fe-4S] clusters in the mitochondrial iron-sulfur cluster assembly machinery.

    PubMed

    Brancaccio, Diego; Gallo, Angelo; Mikolajczyk, Maciej; Zovo, Kairit; Palumaa, Peep; Novellino, Ettore; Piccioli, Mario; Ciofi-Baffoni, Simone; Banci, Lucia

    2014-11-19

    The generation of [4Fe-4S] clusters in mitochondria critically depends, in both yeast and human cells, on two A-type ISC proteins (in mammals named ISCA1 and ISCA2), which perform a nonredundant functional role forming in vivo a heterocomplex. The molecular function of ISCA1 and ISCA2 proteins, i.e., how these proteins help in generating [4Fe-4S] clusters, is still unknown. In this work we have structurally characterized the Fe/S cluster binding properties of human ISCA2 and investigated in vitro whether and how a [4Fe-4S] cluster is assembled when human ISCA1 and ISCA2 interact with the physiological [2Fe-2S](2+) cluster-donor human GRX5. We found that (i) ISCA2 binds either [2Fe-2S] or [4Fe-4S] cluster in a dimeric state, and (ii) two molecules of [2Fe-2S](2+) GRX5 donate their cluster to a heterodimeric ISCA1/ISCA2 complex. This complex acts as an "assembler" of [4Fe-4S] clusters; i.e., the two GRX5-donated [2Fe-2S](2+) clusters generate a [4Fe-4S](2+) cluster. The formation of the same [4Fe-4S](2+) cluster-bound heterodimeric species is also observed by having first one [2Fe-2S](2+) cluster transferred from GRX5 to each individual ISCA1 and ISCA2 proteins to form [2Fe-2S](2+) ISCA2 and [2Fe-2S](2+) ISCA1, and then mixing them together. These findings imply that such heterodimeric complex is the functional unit in mitochondria receiving [2Fe-2S] clusters from hGRX5 and assembling [4Fe-4S] clusters before their transfer to the final target apo proteins.

  2. Identification of two [4Fe-4S]-cluster-containing hydro-lyases from Pyrococcus furiosus.

    PubMed

    van Vugt-Lussenburg, Barbara M A; van der Weel, Laura; Hagen, Wilfred R; Hagedoorn, Peter-Leon

    2009-09-01

    The hyperthermophilic archaeon Pyrococcus furiosus is a strict anaerobe. It is therefore not expected to use the oxidative tricarboxylic acid (TCA) cycle for energy transduction. Nonetheless, its genome encodes more putative TCA cycle enzymes than the closely related Pyrococcus horikoshii and Pyrococcus abyssi, including an aconitase (PF0201). Furthermore, a two-subunit fumarase (PF1755 and PF1754) is encoded on the Pyr. furiosus genome. In the present study, these three genes were heterologously overexpressed in Escherichia coli to enable characterization of the enzymes. PF1755 and PF1754 were shown to form a [4Fe-4S]-cluster-containing heterodimeric enzyme, able to catalyse the reversible hydratation of fumarate. The aconitase PF0201 also contained an Fe-S cluster, and catalysed the conversion from citrate to isocitrate. The fumarase belongs to the class of two-subunit, [4Fe-4S]-cluster-containing fumarate hydratases exemplified by MmcBC from Pelotomaculum thermopropionicum; the aconitase belongs to the aconitase A family. Aconitase probably plays a role in amino acid synthesis when the organism grows on carbohydrates. However, the function of the seemingly metabolically isolated fumarase in Pyr. furiosus has yet to be established.

  3. Protonation and Proton-Coupled Electron Transfer at S-Ligated [4Fe-4S] Clusters

    PubMed Central

    Morris, Wesley D.; Darcy, Julia W.; Mayer, James M.

    2015-01-01

    Biological [Fe-S] clusters are increasingly recognized to undergo proton-coupled electron transfer (PCET), but the site of protonation, mechanism, and role for PCET remains largely unknown. Here we explore this reactivity with synthetic model clusters. Protonation of the arylthiolate-ligated [4Fe-4S] cluster [Fe4S4(SAr)4]2- (1, SAr = S-2,4-6-(iPr)3C6H2) leads to thiol dissociation, reversibly forming [Fe4S4(SAr)3L]1- (2) + ArSH (L = solvent, and/or conjugate base). Solutions of 2 + ArSH react with the nitroxyl radical TEMPO to give [Fe4S4(SAr)4]1- (1ox) and TEMPOH. This reaction involves PCET coupled to thiolate association and may proceed via the unobserved protonated cluster [Fe4S4(SAr)3(HSAr)]1-(1-H). Similar reactions with this and related clusters proceed comparably. An understanding of the PCET thermochemistry of this cluster system has been developed, encompassing three different redox levels and two protonation states. PMID:25965413

  4. Protonation and Proton-Coupled Electron Transfer at S-Ligated [4Fe-4S] Clusters.

    PubMed

    Saouma, Caroline T; Morris, Wesley D; Darcy, Julia W; Mayer, James M

    2015-06-15

    Biological [Fe-S] clusters are increasingly recognized to undergo proton-coupled electron transfer (PCET), but the site of protonation, mechanism, and role for PCET remains largely unknown. Here we explore this reactivity with synthetic model clusters. Protonation of the arylthiolate-ligated [4Fe-4S] cluster [Fe4 S4 (SAr)4 ](2-) (1, SAr=S-2,4-6-(iPr)3 C6 H2 ) leads to thiol dissociation, reversibly forming [Fe4 S4 (SAr)3 L](1-) (2) and ArSH (L=solvent, and/or conjugate base). Solutions of 2+ArSH react with the nitroxyl radical TEMPO to give [Fe4 S4 (SAr)4 ](1-) (1ox ) and TEMPOH. This reaction involves PCET coupled to thiolate association and may proceed via the unobserved protonated cluster [Fe4 S4 (SAr)3 (HSAr)](1-) (1-H). Similar reactions with this and related clusters proceed comparably. An understanding of the PCET thermochemistry of this cluster system has been developed, encompassing three different redox levels and two protonation states. PMID:25965413

  5. Arabidopsis thaliana Nfu2 accommodates [2Fe-2S] or [4Fe-4S] clusters and is competent for in vitro maturation of chloroplast [2Fe-2S] and [4Fe-4S] cluster-containing proteins†

    PubMed Central

    Gao, Huanyao; Subramanian, Sowmya; Couturier, Jérémy; Naik, Sunil; Kim, Sung-Kun; Leustek, Thomas; Knaff, David B.; Wu, Hui-Chen; Vignols, Florence; Huynh, Boi Hanh; Rouhier, Nicolas; Johnson, Michael K.

    2013-01-01

    Nfu-type proteins are essential in the biogenesis of iron-sulfur (Fe-S) clusters in numerous organisms. A number of phenotypes including low levels of Fe-S cluster incorporation are associated with deletion of the gene encoding a chloroplast-specific Nfu-type protein, Nfu2 from Arabidopsis thaliana (AtNfu2). Here we report that recombinant AtNfu2 is able to assemble both [2Fe-2S] and [4Fe-4S] clusters. Analytical data and gel filtration studies support cluster/protein stoichiometries of one [2Fe-2S] cluster/homotetramer and one [4Fe-4S] cluster/homodimer. The combination of UV-visible absorption and circular dichroism, resonance Raman and Mössbauer spectroscopies has been employed to investigate the nature, properties and transfer of the clusters assembled on Nfu2. The results are consistent with subunit-bridging [2Fe-2S]2+ and [4Fe-4S]2+ clusters coordinated by the cysteines in the conserved CXXC motif. The results also provided insight into the specificity of Nfu2 for maturation of chloroplastic Fe-S proteins via intact, rapid and quantitative cluster transfer. [2Fe-2S] cluster-bound Nfu2 is shown to be an effective [2Fe-2S]2+ cluster donor for glutaredoxin S16, but not glutaredoxin S14. Moreover, [4Fe-4S] cluster-bound Nfu2 is shown to be a very rapid and efficient [4Fe-4S]2+ cluster donor for adenosine 5′-phosphosulfate reductase (APR1) and yeast two-hybrid studies indicate that APR1 forms a complex with Nfu2, but not with Nfu1 and Nfu3, the two other chloroplastic Nfu proteins. This cluster transfer is likely to be physiologically relevant and is particularly significant for plant metabolism as APR1 catalyzes the second step in reductive sulfur assimilation which ultimately results in the biosynthesis of cysteine, methionine, glutathione, and Fe-S clusters. PMID:24032747

  6. Identification of FX in the heliobacterial reaction center as a [4Fe-4S] cluster with an S = 3/2 ground spin state.

    PubMed

    Heinnickel, Mark; Agalarov, Rufat; Svensen, Nina; Krebs, Carsten; Golbeck, John H

    2006-05-30

    Type I homodimeric reaction centers, particularly the class present in heliobacteria, are not well understood. Even though the primary amino acid sequence of PshA in Heliobacillus mobilis has been shown to contain an F(X) binding site, a functional Fe-S cluster has not been detected by EPR spectroscopy. Recently, we reported that PshB, which contains F(A)- and F(B)-like Fe-S clusters, could be removed from the Heliobacterium modesticaldum reaction center (HbRC), resulting in 15 ms lifetime charge recombination between P798(+) and an unidentified electron acceptor [Heinnickel, M., Shen, G., Agalarov, R., and Golbeck, J. H. (2005) Biochemistry 44, 9950-9960]. We report here that when a HbRC core is incubated with sodium dithionite in the presence of light, the 15 ms charge recombination is replaced with a kinetic transient in the sub-microsecond time domain, consistent with the reduction of this electron acceptor. Concomitantly, a broad and intense EPR signal arises around g = 5 along with a minor set of resonances around g = 2 similar to the spectrum of the [4Fe-4S](+) cluster in the Fe protein of Azotobacter vinelandii nitrogenase, which exists in two conformations having S = (3)/(2) and S = (1)/(2) ground spin states. The Mössbauer spectrum in the as-isolated HbRC core shows that all of the Fe is present in the form of a [4Fe-4S](2+) cluster. After reduction with sodium dithionite in the presence of light, approximately 65% of the Fe appears in the form of a [4Fe-4S](+) cluster; the remainder is in the [4Fe-4S](2+) state. Analysis of the non-heme iron content of HbRC cores indicates an antenna size of 21.6 +/- 1.1 BChl g molecules/P798. The evidence indicates that the HbRC contains a [4Fe-4S] cluster identified as F(X) that is coordinated between the PshA homodimer; in contrast to F(X) in other type I reaction centers, this [4Fe-4S] cluster exhibits an S = (3)/(2) ground spin state. PMID:16716087

  7. Characterization of [4Fe-4S]-containing and cluster-free forms of Streptomyces WhiD

    PubMed Central

    Crack, Jason C.; den Hengst, Chris D.; Jakimowicz, Piotr; Subramanian, Sowmya; Johnson, Michael K.; Buttner, Mark J.; Thomson, Andrew J.; Le Brun, Nick E.

    2009-01-01

    WhiD, a member of the WhiB-like (Wbl) family of iron-sulfur proteins found exclusively within the actinomycetes, is required for the late stages of sporulation in Streptomyces coelicolor. Like all other Wbl proteins, WhiD has not so far been purified in a soluble form that contains a significant amount of cluster and characterization has relied on cluster-reconstituted protein. Thus, a major goal in Wbl research is to obtain and characterize native protein containing iron-sulfur clusters. Here we report the analysis of S. coelicolor WhiD purified anaerobically from E. coli as a soluble protein containing a single [4Fe-4S]2+ cluster ligated by four cysteines. Upon exposure to oxygen, spectral features associated with the [4Fe-4S] cluster were lost in a slow reaction that unusually yielded apo-WhiD directly without significant concentrations of cluster intermediates. This process was found to be highly pH dependent with an optimal stability observed between pH 7.0 and 8.0. Low molecular weight thiols, including a mycothiol analogue and thioredoxin, exerted a small but significant protective effect against WhiD cluster loss, an activity that could be of physiological importance. [4Fe-4S]2+ WhiD was found to react much more rapidly with superoxide than with either oxygen or hydrogen peroxide, which may also be of physiological significance. Loss of the [4Fe-4S] cluster to form apo-protein destabilized the protein fold significantly, but did not lead to complete unfolding. Finally, apo-WhiD exhibited negligible activity in an insulin-based disulfide reductase assay demonstrating that it does not function as a general protein disulfide reductase. PMID:19954209

  8. Reactions of synthetic [2Fe-2S] and [4Fe-4S] clusters with nitric oxide and nitrosothiols.

    PubMed

    Harrop, Todd C; Tonzetich, Zachary J; Reisner, Erwin; Lippard, Stephen J

    2008-11-19

    The interaction of nitric oxide (NO) with iron-sulfur cluster proteins results in degradation and breakdown of the cluster to generate dinitrosyl iron complexes (DNICs). In some cases the formation of DNICs from such cluster systems can lead to activation of a regulatory pathway or the loss of enzyme activity. In order to understand the basic chemistry underlying these processes, we have investigated the reactions of NO with synthetic [2Fe-2S] and [4Fe-4S] clusters. Reaction of excess NO(g) with solutions of [Fe2S2(SR)4](2-) (R = Ph, p-tolyl (4-MeC6H4), or 1/2 (CH2)2-o-C6H4) cleanly affords the respective DNIC, [Fe(NO)2(SR)2](-), with concomitant reductive elimination of the bridging sulfide ligands as elemental sulfur. The structure of (Et4N)[Fe(NO)2(S-p-tolyl)2] was verified by X-ray crystallography. Reactions of the [4Fe-4S] clusters, [Fe4S4(SR)4](2-) (R = Ph, CH2Ph, (t)Bu, or 1/2 (CH2)-m-C6H4) proceed in the absence of added thiolate to yield Roussin's black salt, [Fe4S3(NO)7](-). In contrast, (Et4N)2[Fe4S4(SPh)4] reacts with NO(g) in the presence of 4 equiv of (Et4N)(SPh) to yield the expected DNIC. For all reactions, we could reproduce the chemistry effected by NO(g) with the use of trityl-S-nitrosothiol (Ph3CSNO) as the nitric oxide source. These results demonstrate possible pathways for the reaction of iron-sulfur clusters with nitric oxide in biological systems and highlight the importance of thiolate-to-iron ratios in stabilizing DNICs.

  9. A PAS domain with an oxygen labile [4Fe-4S](2+) cluster in the oxygen sensor kinase NreB of Staphylococcus carnosus.

    PubMed

    Müllner, Martin; Hammel, Oliver; Mienert, Bernd; Schlag, Steffen; Bill, Eckhard; Unden, Gottfried

    2008-12-30

    The cytoplasmic histidine sensor kinase NreB of Staphylococcus carnosus responds to O(2) and controls together with the response regulator NreC the expression of genes of nitrate/nitrite respiration. nreBC homologous genes were found in Staphylococcus strains and Bacillus clausii, and a modified form was found in some Lactobacillus strains. NreB contains a sensory domain with similarity to heme B binding PAS domains. Anaerobically prepared NreB of S. carnosus exhibited a (diamagnetic) [4Fe-4S](2+) cluster when assessed by Mossbauer spectroscopy. Upon reaction with air, the cluster was degraded with a half-life of approximately 2.5 min. No significant amounts of Mossbauer or EPR detectable intermediates were found during the decay, but magnetic Mossbauer spectra revealed formation of diamagnetic [2Fe-2S](2+) clusters. After extended exposure to air, NreB was devoid of a FeS cluster. Photoreduction with deazaflavin produced small amounts of [4Fe-4S](+), which were degraded subsequently. The magnetically perturbed Mossbauer spectrum of the [4Fe-4S](2+) cluster corroborated the S = 0 spin state and revealed uniform electric field gradient tensors of the iron sites, suggesting full delocalization of the valence electrons and binding of each of the Fe ions by four S ligands, including the ligand to the protein. Mutation of each of the four Cys residues inactivated NreB function in vivo in accordance with their role as ligands. [4Fe-4S](2+) cluster-containing NreB had high kinase activity. Exposure to air decreased the kinase activity and content of the [4Fe-4S](2+) cluster with similar half-lives. We conclude that the sensory domain of NreB represents a new type of PAS domain containing a [4Fe-4S](2+) cluster for sensing and function. PMID:19102705

  10. Probing Ligand Effects on the Redox Energies of [4Fe-4S] Clusters Using Broken-Symmetry Density Functional Theory

    SciTech Connect

    Niu, Shuqiang; Ichiye, Toshiko

    2009-05-14

    A central issue in understanding redox properties of iron-sulfur proteins is determining the factors that tune the reduction potentials of the Fe-S clusters. Recently, Solomon and coworkers have shown that the Fe-S bond covalency of protein analogs measured by %L, the percent ligand character of the Fe 3d orbitals, from ligand K-edge X-ray absorption spectroscopy (XAS) correlates with the electrochemical redox potentials. Also, Wang and coworkers have measured electron detachment energies for iron-sulfur clusters without environmental perturbations by gas-phase photoelectron spectroscopy (PES). Here the correlations of the ligand character with redox energy and %L character are examined in [Fe₄S₄L₄]2⁻ clusters with different ligands by broken symmetry density functional theory (BS-DFT) calculations using the B3LYP functional together with PES and XAS experimental results. These gas-phase studies assess ligand effects independently of environmental perturbations and thus provide essential information for computational studies of iron-sulfur proteins. The B3LYP oxidation energies agree well with PES data, and the %L character obtained from natural bond orbital analysis correlates with XAS values, although it systematically underestimates them because of basis set effects. The results show that stronger electron-donating terminal ligands increase %Lt, the percent ligand character from terminal ligands, but decrease %Sb, the percent ligand character from the bridging sulfurs. Because the oxidized orbital has significant Fe-Lt antibonding character, the oxidation energy correlates well with %Lt. However, because the reduced orbital has varying contributions of both Fe-Lt and Fe-Sb antibonding character, the reduction energy does not correlate with either %Lt or %Sb. Overall, BSDFT calculations together with XAS and PES experiments can unravel the complex underlying factors in the redox energy and chemical bonding of the [4Fe-4S] clusters in iron-sulfur proteins.

  11. Probing the intrinsic electronic structure of the cubane [4Fe-4S] cluster: nature's favorite cluster for electron transfer and storage.

    PubMed

    Wang, Xue-Bin; Niu, Shuqiang; Yang, Xin; Ibrahim, Saad K; Pickett, Christopher J; Ichiye, Toshiko; Wang, Lai-Sheng

    2003-11-19

    The cubane [4Fe-4S] is the most common multinuclear metal center in nature for electron transfer and storage. Using electrospray, we produced a series of gaseous doubly charged cubane-type complexes, [Fe4S4L4]2- (L = -SC2H5, -SH, -Cl, -Br, -I) and the Se-analogues [Fe4Se4L4]2- (L = -SC2H5, -Cl), and probed their electronic structures with photoelectron spectroscopy and density functional calculations. The photoelectron spectral features are similar among all the seven species investigated, revealing a weak threshold feature due to the minority spins on the Fe centers and confirming the low-spin two-layer model for the [4Fe-4S](2+) core and its "inverted level scheme". The measured adiabatic detachment energies, which are sensitive to the terminal ligand substitution, provide the intrinsic oxidation potentials of the [Fe4S4L4]2- complexes. The calculations revealed a simple correlation between the electron donor property of the terminal thiolate as well as the bridging sulfide with the variation of the intrinsic redox potentials. Our data provide intrinsic electronic structure information of the [4Fe-4S] cluster and the molecular basis for understanding the protein and solvent effects on the redox properties of the [4Fe-4S] active sites.

  12. The conserved protein Dre2 uses essential [2Fe-2S] and [4Fe-4S] clusters for its function in cytosolic iron-sulfur protein assembly.

    PubMed

    Netz, Daili J A; Genau, Heide M; Weiler, Benjamin D; Bill, Eckhard; Pierik, Antonio J; Lill, Roland

    2016-07-15

    The cytosolic iron-sulfur (Fe-S) protein assembly (CIA) machinery comprises 11 essential components and matures Fe-S proteins involved in translation and genome maintenance. Maturation is initiated by the electron transfer chain NADPH-diflavin reductase Tah18-Fe-S protein Dre2 that facilitates the de novo assembly of a [4Fe-4S] cluster on the scaffold complex Cfd1-Nbp35. Tah18-Dre2 also play a critical role in the assembly of the diferric tyrosyl radical cofactor of ribonucleotide reductase. Dre2 contains eight conserved cysteine residues as potential co-ordinating ligands for Fe-S clusters but their functional importance and the type of bound clusters is unclear. In the present study, we use a combination of mutagenesis, cell biological and biochemical as well as UV-visible, EPR and Mössbauer spectroscopic approaches to show that the yeast Dre2 cysteine residues Cys(252), Cys(263), Cys(266) and Cys(268) (motif I) bind a [2Fe-2S] cluster, whereas cysteine residues Cys(311), Cys(314), Cys(322) and Cys(325) (motif II) co-ordinate a [4Fe-4S] cluster. All of these residues with the exception of Cys(252) are essential for cell viability, cytosolic Fe-S protein activity and in vivo (55)Fe-S cluster incorporation. The N-terminal methyltransferase-like domain of Dre2 is important for proper Fe-S cluster assembly at motifs I and II, which occurs in an interdependent fashion. Our findings further resolve why recombinant Dre2 from Arabidopsis, Trypanosoma or humans has previously been isolated with a single [2Fe-2S] instead of native [2Fe-2S] plus [4Fe-4S] clusters. In the presence of oxygen, the motif I-bound [2Fe-2S] cluster is labile and the motif II-bound [4Fe-4S] cluster is readily converted into a [2Fe-2S] cluster.

  13. NsrR from Streptomyces coelicolor Is a Nitric Oxide-sensing [4Fe-4S] Cluster Protein with a Specialized Regulatory Function*

    PubMed Central

    Crack, Jason C.; Munnoch, John; Dodd, Erin L.; Knowles, Felicity; Al Bassam, Mahmoud M.; Kamali, Saeed; Holland, Ashley A.; Cramer, Stephen P.; Hamilton, Chris J.; Johnson, Michael K.; Thomson, Andrew J.; Hutchings, Matthew I.; Le Brun, Nick E.

    2015-01-01

    The Rrf2 family transcription factor NsrR controls expression of genes in a wide range of bacteria in response to nitric oxide (NO). The precise form of the NO-sensing module of NsrR is the subject of controversy because NsrR proteins containing either [2Fe-2S] or [4Fe-4S] clusters have been observed previously. Optical, Mössbauer, resonance Raman spectroscopies and native mass spectrometry demonstrate that Streptomyces coelicolor NsrR (ScNsrR), previously reported to contain a [2Fe-2S] cluster, can be isolated containing a [4Fe-4S] cluster. ChIP-seq experiments indicated that the ScNsrR regulon is small, consisting of only hmpA1, hmpA2, and nsrR itself. The hmpA genes encode NO-detoxifying flavohemoglobins, indicating that ScNsrR has a specialized regulatory function focused on NO detoxification and is not a global regulator like some NsrR orthologues. EMSAs and DNase I footprinting showed that the [4Fe-4S] form of ScNsrR binds specifically and tightly to an 11-bp inverted repeat sequence in the promoter regions of the identified target genes and that DNA binding is abolished following reaction with NO. Resonance Raman data were consistent with cluster coordination by three Cys residues and one oxygen-containing residue, and analysis of ScNsrR variants suggested that highly conserved Glu-85 may be the fourth ligand. Finally, we demonstrate that some low molecular weight thiols, but importantly not physiologically relevant thiols, such as cysteine and an analogue of mycothiol, bind weakly to the [4Fe-4S] cluster, and exposure of this bound form to O2 results in cluster conversion to the [2Fe-2S] form, which does not bind to DNA. These data help to account for the observation of [2Fe-2S] forms of NsrR. PMID:25771538

  14. Mutational analysis of the [4Fe-4S]-cluster converting iron regulatory factor from its RNA-binding form to cytoplasmic aconitase.

    PubMed Central

    Hirling, H; Henderson, B R; Kühn, L C

    1994-01-01

    The control of cellular iron homeostasis involves the coordinate post-transcriptional regulation of ferritin mRNA translation and transferring receptor mRNA stability. These regulatory events are mediated by a soluble cytoplasmic protein, iron regulatory factor (IRF), which binds specifically to mRNA hairpin structures, termed iron-responsive elements (IREs), in the respective mRNAs. IRF is modulated by variations of cellular iron levels and exists as either an apo-protein or a [4Fe-4S]-cluster protein. The two conformations show distinct, mutually exclusive functions. High-affinity IRE binding is observed with the apo-form induced by iron deprivation, but is lost under high iron conditions when IRF is converted to the [4Fe-4S]-cluster form which shows cytoplasmic aconitase activity. Moreover, IRE binding is inactivated by the sulfhydryl-oxidizing agent diamide and fully activated in vitro by 2% 2-mercapto-ethanol, whereas alkylation of IRF inhibits IRE binding. In the present study, we analyzed each of the above features using site-directed mutants of recombinant human IRF. The results support the bifunctional nature of IRF. We conclude that cysteines 437, 503 and 506 anchor the [4Fe-4S]-cluster, and are essential to the aconitase activity. Mutagenesis changing any of the cysteines to serine leads to constitutive RNA binding in 0.02% 2-mercaptoethanol. Cysteine 437 is particularly critical to the RNA-protein interaction. The spontaneous or diamide-induced formation of disulfide bonds between cysteines 437 and 503 or 437 and 506, in apo-IRF, as well as its alkylation by N-ethylmaleimide, inhibit binding to the IRE.(ABSTRACT TRUNCATED AT 250 WORDS) Images PMID:7508861

  15. Transformation of dinitrosyl iron complexes [(NO)2Fe(SR)2]- (R = Et, Ph) into [4Fe-4S] Clusters [Fe4S4(SPh)4]2-: relevance to the repair of the nitric oxide-modified ferredoxin [4Fe-4S] clusters.

    PubMed

    Tsou, Chih-Chin; Lin, Zong-Sian; Lu, Tsai-Te; Liaw, Wen-Feng

    2008-12-17

    Transformation of dinitrosyl iron complexes (DNICs) [(NO)(2)Fe(SR)(2)](-) (R = Et, Ph) into [4Fe-4S] clusters [Fe(4)S(4)(SPh)(4)](2-) in the presence of [Fe(SPh)(4)](2-/1-) and S-donor species S(8) via the reassembling process ([(NO)(2)Fe(SR)(2)](-) --> [Fe(4)S(3)(NO)(7)](-) (1)/[Fe(4)S(3)(NO)(7)](2-) (2) --> [Fe(4)S(4)(NO)(4)](2-) (3) --> [Fe(4)S(4)(SPh)(4)](2-) (5)) was demonstrated. Reaction of [(NO)(2)Fe(SR)(2)](-) (R = Et, Ph) with S(8) in THF, followed by the addition of HBF(4) into the mixture solution, yielded complex [Fe(4)S(3)(NO)(7)](-) (1). Complex [Fe(4)S(3)(NO)(7)](2-) (2), obtained from reduction of complex 1 by [Na][biphenyl], was converted into complex [Fe(4)S(4)(NO)(4)](2-) (3) along with byproduct [(NO)(2)Fe(SR)(2)](-) via the proposed [Fe(4)S(3)(SPh)(NO)(4)](2-) intermediate upon treating complex 2 with 1.5 equiv of [Fe(SPh)(4)](2-) and the subsequent addition of 1/8 equiv of S(8) in CH(3)CN at ambient temperature. Complex 3 was characterized by IR, UV-vis, and single-crystal X-ray diffraction. Upon addition of complex 3 to the CH(3)CN solution of [Fe(SPh)(4)](-) in a 1:2 molar ratio at ambient temperature, the rapid NO radical-thiyl radical exchange reaction between complex 3 and the biomimetic oxidized form of rubredoxin [Fe(SPh)(4)](-) occurred, leading to the simultaneous formation of [4Fe-4S] cluster [Fe(4)S(4)(SPh)(4)](2-) (5) and DNIC [(NO)(2)Fe(SPh)(2)](-). This result demonstrates a successful biomimetic reassembly of [4Fe-4S] cluster [Fe(4)S(4)(SPh)(4)](2-) from NO-modified [Fe-S] clusters, relevant to the repair of DNICs derived from nitrosylation of [4Fe-4S] clusters of endonuclease III back to [4Fe-4S] clusters upon addition of ferrous ion, cysteine, and IscS.

  16. Role of the [4Fe-4S] cluster in reductive activation of the cobalt center of the corrinoid iron-sulfur protein from Clostridium thermoaceticum during acetate biosynthesis.

    PubMed

    Menon, S; Ragsdale, S W

    1998-04-21

    The corrinoid iron-sulfur protein (CFeSP) from Clostridium thermoaceticum functions as a methyl carrier in the Wood-Ljungdahl pathway of acetyl-CoA synthesis. The small subunit (33 kDa) contains cobalt in a corrinoid cofactor, and the large subunit (55 kDa) contains a [4Fe-4S] cluster. The cobalt center is methylated by methyltetrahydrofolate (CH3-H4folate) to form a methylcobalt intermediate and, subsequently, is demethylated by carbon monoxide dehydrogenase/acetyl-CoA synthase (CODH/ACS). The work described here demonstrates that the [4Fe-4S] cluster is required to facilitate the reactivation of oxidatively inactivated Cob(II)amide to the active Co(I) state. Site-directed mutagenesis of the large subunit gene was used to change residue 20 from cysteine to alanine, which resulted in formation of a cluster with EPR and redox properties consistent with those of [3Fe-4S] clusters. The midpoint potential of the cluster in the C20A variant was approximately 500 mV more positive than that of the [4Fe-4S] cluster in the native enzyme. Accordingly, it was found that the Co center in the C20A mutant protein could be reduced artificially but was severely crippled in its ability to be reduced by physiological electron donors. This is probably because the reduced cluster of the C20A protein cannot provide the driving force needed to reduce Co(II) to Co(I), since the Co(II/I) midpoint potential is -504 mV. The C20A variant also was unable to catalyze the steady-state synthesis of acetyl-CoA when CH3-H4folate or methyl iodide were provided as methyl donors and CO and CODH/ACS as reductants. Addition of chemical reductants rescued the catalytically crippled variant form in both of these reactions. On the other hand, in single-turnover reactions, the methyl-Co state of the altered protein was fully active in methylating H4folate and in synthesizing acetyl-CoA in the presence of CO and CoA. The combined results strongly indicate that the FeS cluster of the CFeSP is necessary for

  17. Two [4Fe-4S] clusters containing radical SAM enzyme SkfB catalyze thioether bond formation during the maturation of the sporulation killing factor.

    PubMed

    Flühe, Leif; Burghaus, Olaf; Wieckowski, Beata M; Giessen, Tobias W; Linne, Uwe; Marahiel, Mohamed A

    2013-01-23

    The sporulation killing factor (SKF) is a 26-residue ribosomally assembled and posttranslationally modified sactipeptide. It is produced by Bacillus subtilis 168 and plays a key role in its sporulation. Like all sactipeptides, SKF contains a thioether bond, which links the cysteine residue Cys4 with the α-carbon of the methionine residue Met12. In this study we demonstrate that this bond is generated by the two [4Fe-4S] clusters containing radical SAM enzyme SkfB, which is encoded in the skf operon. By mutational analysis of both cluster-binding sites, we were able to postulate a mechanism for thioether generation which is in agreement with that of AlbA. Furthermore, we were able to show that thioether bond formation is specific toward hydrophobic amino acids at the acceptor site. Additionally we demonstrate that generation of the thioether linkage is leader-peptide-dependent, suggesting that this reaction is the first step in SKF maturation. PMID:23282011

  18. Insights into eukaryotic DNA priming from the structure and functional interactions of the 4Fe-4S cluster domain of human DNA primase

    SciTech Connect

    Vaithiyalingam, Sivaraja; Warren, Eric M.; Eichman, Brandt F.; Chazin, Walter J.

    2010-10-19

    DNA replication requires priming of DNA templates by enzymes known as primases. Although DNA primase structures are available from archaea and bacteria, the mechanism of DNA priming in higher eukaryotes remains poorly understood in large part due to the absence of the structure of the unique, highly conserved C-terminal regulatory domain of the large subunit (p58C). Here, we present the structure of this domain determined to 1.7-{angstrom} resolution by X-ray crystallography. The p58C structure reveals a novel arrangement of an evolutionarily conserved 4Fe-4S cluster buried deeply within the protein core and is not similar to any known protein structure. Analysis of the binding of DNA to p58C by fluorescence anisotropy measurements revealed a strong preference for ss/dsDNA junction substrates. This approach was combined with site-directed mutagenesis to confirm that the binding of DNA occurs to a distinctively basic surface on p58C. A specific interaction of p58C with the C-terminal domain of the intermediate subunit of replication protein A (RPA32C) was identified and characterized by isothermal titration calorimetry and NMR. Restraints from NMR experiments were used to drive computational docking of the two domains and generate a model of the p58C-RPA32C complex. Together, our results explain functional defects in human DNA primase mutants and provide insights into primosome loading on RPA-coated ssDNA and regulation of primase activity.

  19. Structure of C42D Azotobacter vinelandii FdI. A Cys-X-X-Asp-X-X-Cys motif ligates an air-stable [4Fe-4S]2+/+ cluster.

    PubMed

    Jung, Y S; Bonagura, C A; Tilley, G J; Gao-Sheridan, H S; Armstrong, F A; Stout, C D; Burgess, B K

    2000-11-24

    All naturally occurring ferredoxins that have Cys-X-X-Asp-X-X-Cys motifs contain [4Fe-4S](2+/+) clusters that can be easily and reversibly converted to [3Fe-4S](+/0) clusters. In contrast, ferredoxins with unmodified Cys-X-X-Cys-X-X-Cys motifs assemble [4Fe-4S](2+/+) clusters that cannot be easily interconverted with [3Fe-4S](+/0) clusters. In this study we changed the central cysteine of the Cys(39)-X-X-Cys(42)-X-X-Cys(45) of Azotobacter vinelandii FdI, which coordinates its [4Fe-4S](2+/+) cluster, into an aspartate. UV-visible, EPR, and CD spectroscopies, metal analysis, and x-ray crystallography show that, like native FdI, aerobically purified C42D FdI is a seven-iron protein retaining its [4Fe-4S](2+/+) cluster with monodentate aspartate ligation to one iron. Unlike known clusters of this type the reduced [4Fe-4S](+) cluster of C42D FdI exhibits only an S = 1/2 EPR with no higher spin signals detected. The cluster shows only a minor change in reduction potential relative to the native protein. All attempts to convert the cluster to a 3Fe cluster using conventional methods of oxygen or ferricyanide oxidation or thiol exchange were not successful. The cluster conversion was ultimately accomplished using a new electrochemical method. Hydrophobic and electrostatic interaction and the lack of Gly residues adjacent to the Asp ligand explain the remarkable stability of this cluster.

  20. A Geometric and Electrostatic Study of the [4Fe-4S] Cluster of Adenosine-5´-Phosphosulfate Reductase from Broken Symmetry Density Functional Calculations and Extended X-ray Absorption Fine Structure Spectroscopy

    PubMed Central

    Bhave, Devayani P.; Han, Wen-Ge; Pazicni, Samuel; Penner-Hahn, James E.; Carroll, Kate S.; Noodleman, Louis

    2011-01-01

    Adenosine-5’-phosphosulfate reductase (APSR) is an iron-sulfur protein that catalyses the reduction of adenosine-5’-phosphosulfate (APS) to sulfite. APSR coordinates to a [4Fe-4S] cluster via a conserved CC-X~80-CXXC motif and the cluster is essential for catalysis. Despite extensive functional, structural and spectroscopic studies, the exact role of the iron-sulfur cluster in APS reduction remains unknown. To gain an understanding into the role of the cluster, density functional theory (DFT) analysis and extended X-ray fine structure spectroscopy (EXAFS) have been performed to reveal insights into the coordination, geometry and electrostatics of the [4Fe-4S] cluster. XANES data confirms that the cluster is in the [4Fe-4S]2+ state in both native and substrate-bound APSR while EXAFS data recorded at ~0.1 Å resolution indicates that there is no significant change in the structure of the [4Fe-4S] cluster between the native and substrate-bound forms of the protein. On the other hand, DFT calculations provide an insight into the subtle differences between the geometry of the cluster in the native and APS-bound forms of APSR. A comparison between models with and without the tandem cysteine pair coordination of the cluster suggests a role for the unique coordination in facilitating a compact geometric structure and ‘fine-tuning’ the electronic structure to prevent reduction of the cluster. Further, calculations using models in which residue Lys144 is mutated to Ala confirm the finding that Lys144 serves as a crucial link in the interactions involving the [4Fe-4S] cluster and APS. PMID:21678934

  1. 4-Demethylwyosine Synthase from Pyrococcus abyssi Is a Radical-S-adenosyl-l-methionine Enzyme with an Additional [4Fe-4S]+2 Cluster That Interacts with the Pyruvate Co-substrate*

    PubMed Central

    Perche-Letuvée, Phanélie; Kathirvelu, Velavan; Berggren, Gustav; Clemancey, Martin; Latour, Jean-Marc; Maurel, Vincent; Douki, Thierry; Armengaud, Jean; Mulliez, Etienne; Fontecave, Marc; Garcia-Serres, Ricardo; Gambarelli, Serge; Atta, Mohamed

    2012-01-01

    Wybutosine and its derivatives are found in position 37 of tRNA encoding Phe in eukaryotes and archaea. They are believed to play a key role in the decoding function of the ribosome. The second step in the biosynthesis of wybutosine is catalyzed by TYW1 protein, which is a member of the well established class of metalloenzymes called “Radical-SAM.” These enzymes use a [4Fe-4S] cluster, chelated by three cysteines in a CX3CX2C motif, and S-adenosyl-l-methionine (SAM) to generate a 5′-deoxyadenosyl radical that initiates various chemically challenging reactions. Sequence analysis of TYW1 proteins revealed, in the N-terminal half of the enzyme beside the Radical-SAM cysteine triad, an additional highly conserved cysteine motif. In this study we show by combining analytical and spectroscopic methods including UV-visible absorption, Mössbauer, EPR, and HYSCORE spectroscopies that these additional cysteines are involved in the coordination of a second [4Fe-4S] cluster displaying a free coordination site that interacts with pyruvate, the second substrate of the reaction. The presence of two distinct iron-sulfur clusters on TYW1 is reminiscent of MiaB, another tRNA-modifying metalloenzyme whose active form was shown to bind two iron-sulfur clusters. A possible role for the second [4Fe-4S] cluster in the enzyme activity is discussed. PMID:23043105

  2. A Cysteine-Rich CCG Domain Contains a Novel [4Fe-4S] Cluster Binding Motif As Deduced From Studies With Subunit B of Heterodisulfide Reductase From Methanothermobacter Marburgensis

    SciTech Connect

    Hamann, N.; Mander, G.J.; Shokes, J.E.; Scott, R.A.; Bennati, M.; Hedderich, R.

    2009-06-01

    Heterodisulfide reductase (HDR) of methanogenic archaea with its active-site [4Fe-4S] cluster catalyzes the reversible reduction of the heterodisulfide (CoM-S-S-CoB) of the methanogenic coenzyme M (CoM-SH) and coenzyme B (CoB-SH). CoM-HDR, a mechanistic-based paramagnetic intermediate generated upon half-reaction of the oxidized enzyme with CoM-SH, is a novel type of [4Fe-4S]{sup 3+} cluster with CoM-SH as a ligand. Subunit HdrB of the Methanothermobacter marburgensis HdrABC holoenzyme contains two cysteine-rich sequence motifs (CX{sub 31-39}CCX{sub 35-36}CXXC), designated as CCG domain in the Pfam database and conserved in many proteins. Here we present experimental evidence that the C-terminal CCG domain of HdrB binds this unusual [4Fe-4S] cluster. HdrB was produced in Escherichia coli, and an iron-sulfur cluster was subsequently inserted by in vitro reconstitution. In the oxidized state the cluster without the substrate exhibited a rhombic EPR signal (g{sub zyx} = 2.015, 1.995, and 1.950) reminiscent of the CoM-HDR signal. {sup 57}Fe ENDOR spectroscopy revealed that this paramagnetic species is a [4Fe-4S] cluster with {sup 57}Fe hyperfine couplings very similar to that of CoM-HDR. CoM-{sup 33}SH resulted in a broadening of the EPR signal, and upon addition of CoM-SH the midpoint potential of the cluster was shifted to values observed for CoM-HDR, both indicating binding of CoM-SH to the cluster. Site-directed mutagenesis of all 12 cysteine residues in HdrB identified four cysteines of the C-terminal CCG domain as cluster ligands. Combined with the previous detection of CoM-HDR-like EPR signals in other CCG domain-containing proteins our data indicate a general role of the C-terminal CCG domain in coordination of this novel [4Fe-4S] cluster. In addition, Zn K-edge X-ray absorption spectroscopy identified an isolated Zn site with an S{sub 3}(O/N){sub 1} geometry in HdrB and the HDR holoenzyme. The N-terminal CCG domain is suggested to provide ligands to the Zn

  3. Dynamics of the [4Fe-4S] Cluster in Pyrococcus furiosus D14C Ferredoxin via Nuclear Resonance Vibrational and Resonance Raman Spectroscopies, Force Field Simulations, and Density Functional Theory Calculations

    PubMed Central

    Mitra, Devrani; Pelmenschikov, Vladimir; Guo, Yisong; Case, David A.; Wang, Hongxin; Dong, Weibing; Tan, Ming-Liang; Ichiye, Toshiko; Jenney, Francis E.; Adams, Michael W. W.; Yoda, Yoshitaka; Zhao, Jiyong; Cramer, Stephen P.

    2011-01-01

    We have used 57Fe nuclear resonance vibrational spectroscopy (NRVS) to study oxidized and reduced forms of the [4Fe-4S] cluster in the D14C variant ferredoxin from Pyrococcus furiosus (Pf D14C Fd). To assist the normal mode assignments, we recorded the NRVS of D14C ferredoxin samples with 36S substituted into the [4Fe-4S] cluster bridging sulfide positions, and a model compound without ligand side chains: (Ph4P)2[Fe4S4Cl4]. Several distinct regions of NRVS intensity are identified, ranging from `protein' and torsional modes below 100 cm−1, through bending and breathing modes near 150 cm−1, to strong bands from Fe-S stretching modes between 250 cm−1 and ~400 cm−1. The oxidized ferredoxin samples were also investigated by resonance Raman (RR) spectroscopy. We found good agreement between NRVS and RR frequencies, but because of different selection rules, the intensities vary dramatically between the two types of spectra. The 57Fe partial vibrational densities of states (PVDOS) for the oxidized samples were interpreted by normal mode analysis with optimization of Urey-Bradley force fields for local models of the [4Fe-4S] clusters. Full protein model calculations were also conducted using a supplemented CHARMM force field, and these calculations revealed low frequency modes that may be relevant to electron transfer with Pf Fd partners. Density functional theory (DFT) calculations complemented these empirical analyses, and DFT was used to estimate the reorganization energy associated with the [Fe4S4]2+/1+ redox cycle. Overall, the NRVS technique demonstrates great promise for the observation and quantitative interpretation of the dynamical properties of Fe-S proteins. PMID:21500788

  4. Rhodobacter sphaeroides rdxA, a homolog of Rhizobium meliloti fixG, encodes a membrane protein which may bind cytoplasmic [4Fe-4S] clusters.

    PubMed Central

    Neidle, E L; Kaplan, S

    1992-01-01

    In the photosynthetic bacterium Rhodobacter sphaeroides, a chromosomal gene, rdxA, which encodes a 52-kDa protein, was found to be homologous to fixG, the first gene of a Rhizobium meliloti nitrogen fixation operon on the pSym plasmid (D. Kahn, M. David, O. Domergue, M.-L. Daveran, J. Ghai, P. R. Hirsch, and J. Batut, J. Bacteriol. 171:929-939, 1989). The deduced amino acid sequences of RdxA and FixG are 53% identical and 73% similar; sequence analyses suggested that each has five transmembrane helices and a central region resembling bacterial-type ferredoxins. Translational fusion proteins with an alkaline phosphatase reporter group were expressed in both R. sphaeroides and Escherichia coli and were used to assess the membrane topology of RdxA. Its ferredoxinlike sequence, which may bind two [4Fe-4S] centers, was found to be cytoplasmically located. Genetic disruptions showed that rdxA is not essential for nitrogen fixation in R. sphaeroides. Immediately downstream of rdxA, an open reading frame (ORFT2) that encoded a 48-kDa protein was found. This DNA sequence was not homologous to any region of the R. meliloti fixG operon. The N-terminal sequence of the ORFT2 gene product resembled amino acid sequences found in members of the GntR family of regulatory proteins (D. J. Haydon and J. R. Guest, FEMS Microbiol. Lett. 79:291-296, 1991). The rdxA gene was localized to the smaller of two R. sphaeroides chromosomes, upstream of and divergently transcribed from hemT, which encodes one of two 5-aminolevulinate synthase isozymes. The rdxA and hemT genes may share a transcriptional regulatory region. Southern hybridization analysis demonstrated the presence of an rdxA homolog on the R. sphaeroides large chromosome. The functions of this homolog, like those of rdxA, remain to be determined, but roles in oxidation-reduction processes are likely. Images PMID:1400197

  5. Collision Induced Dissociation of [4Fe-4S] Cubane Cluster Complexes: [Fe4S4C14-x(SC2H5)x]2-/1- (x=0-4)

    SciTech Connect

    Fu, Youjun; Laskin, Julia; Wang, Lai S.

    2006-09-01

    Collision-induced dissociation (CID) experiments on a series of [4Fe-4S] cluster ions, [Fe4S4Cl4-x(SC2H5)x]2-/1- (x = 0 - 4), revealed that their fragmentation channels change with the coordination environment. Among the three Coulomb repulsion related channels for the doubly charged species, the collision induced electron detachment channel was found to become more significant from x = 0 to 4 due to the decreasing electron binding energies and the magnitude of the repulsion Coulomb barrier, while both the ligand detachment of Cl- and the fission of the [Fe4S4]2+ core became more and more significant with the increase of the Cl- coordination, and eventually became the dominant channel at x = 0. From the parents containing the -SC2H5 ligand, neutral losses of HSC2H5 (62) and/or HSCH=CH2 (60) were observed. It was proposed that inter- and intra-ligand proton transfer could happen during the CID process, resulting in hydrogen coordination to the [4Fe-4S] cluster. In the presence of O2, [Fe4S4Cl3(SC2H5)]2- and [Fe4S4Cl4]2- can form the O2-substituted products [Fe4S4Cl2(SC2H5)O2]- and [Fe4S4Cl3O2]-, respectively. It was shown that the O2 complexation occurs by coordination to the empty iron site of the [4Fe-4S] cubane core after dissociation of one Cl- ligand.

  6. Position of the ATP-binding site of the Fe-protein relative to the iron-sulfur clusters 4Fe-4S and the iron-molybdenum-containing cofactor

    SciTech Connect

    Kondrat'eva, T.A.; Gvozdev, R.I.; Mitsova, I.Z.

    1986-06-10

    Nitrogenase was affinity labeled with epsilon-ATP at the ATP-binding sites and separated into protein components by ion exchange chromatography. In spectrofluorometric titration of the labeled Fe-protein with the native MoFe-protein from the wild strain of Azotobacter and the MoFe-protein not containing iron-sulfur clusters 4Fe-4S, a 4-6-fold quenching of the fluorescence of immobilized epsilon-ATP was observed. When the labeled Fe-protein was titrated with MoFe-protein from the Azotobacter mutant UW-45, on the contrary, there was a four-fold increase in the fluorescence of immobilized epsilon-ATP. Since the MoFe-protein of the Azotobacter mutant UW-45 differs from the MoFe-protein from the wild strain of Azotobacter only by the absence of an iron-molybdenum-containing cofactor (Fe-Mo-cofactor), it is suggested that the ATP-binding site of the Fe-protein is situated next to the FeMo-cofactor and at a distance from the iron-sulfur clusters 4Fe-4S when a complex is formed with the MoFe-protein. The formation of a complex is accompanied by a change in the conformation of the Fe-protein.

  7. Mechanistic Insight into the Symmetric Fission of [4Fe-4S] Analogue Complexes and Implications for Cluster Conversions in Iron-Sulfur Proteins

    SciTech Connect

    Niu, Shuqiang; Wang, Xue B.; Yang, Xin; Wang, Lai-Sheng; Ichiye, Toshiko

    2004-08-12

    Assembly and disassembly of protein-bound iron-sulfur clusters are involved in a wide variety of vital biological processes, ranging from stabilization of protein structures to signaling and sensing of environmental conditions such as changes of Fe or O2 concentrations.

  8. ChlR Protein of Synechococcus sp. PCC 7002 Is a Transcription Activator That Uses an Oxygen-sensitive [4Fe-4S] Cluster to Control Genes involved in Pigment Biosynthesis*

    PubMed Central

    Ludwig, Marcus; Pandelia, Maria-Eirini; Chew, Chyue Yie; Zhang, Bo; Golbeck, John H.; Krebs, Carsten; Bryant, Donald A.

    2014-01-01

    Synechococcus sp. PCC 7002 and many other cyanobacteria have two genes that encode key enzymes involved in chlorophyll a, biliverdin, and heme biosynthesis: acsFI/acsFII, ho1/ho2, and hemF/hemN. Under atmospheric O2 levels, AcsFI synthesizes 3,8-divinyl protochlorophyllide from Mg-protoporphyrin IX monomethyl ester, Ho1 oxidatively cleaves heme to form biliverdin, and HemF oxidizes coproporphyrinogen III to protoporphyrinogen IX. Under microoxic conditions, another set of genes directs the synthesis of alternative enzymes AcsFII, Ho2, and HemN. In Synechococcus sp. PCC 7002, open reading frame SynPCC7002_A1993 encodes a MarR family transcriptional regulator, which is located immediately upstream from the operon comprising acsFII, ho2, hemN, and desF (the latter encodes a putative fatty acid desaturase). Deletion and complementation analyses showed that this gene, denoted chlR, is a transcriptional activator that is essential for transcription of the acsFII-ho2-hemN-desF operon under microoxic conditions. Global transcriptome analyses showed that ChlR controls the expression of only these four genes. Co-expression of chlR with a yfp reporter gene under the control of the acsFII promoter from Synechocystis sp. PCC 6803 in Escherichia coli demonstrated that no other cyanobacterium-specific components are required for proper functioning of this regulatory circuit. A combination of analytical methods and Mössbauer and EPR spectroscopies showed that reconstituted, recombinant ChlR forms homodimers that harbor one oxygen-sensitive [4Fe-4S] cluster. We conclude that ChlR is a transcriptional activator that uses a [4Fe-4S] cluster to sense O2 levels and thereby control the expression of the acsFII-ho2-hemN-desF operon. PMID:24782315

  9. Structure and Function of Four Classes of the 4Fe-4S Protein, IspH.

    PubMed

    Rao, Guodong; Oldfield, Eric

    2016-07-26

    IspH, (E)-1-hydroxy-2-methyl-but-2-enyl 4-diphosphate reductase, is an essential enzyme in isoprenoid biosynthesis and an important drug/herbicide target. Using X-ray crystallographic, bioinformatics, mutagenesis/kinetics/stability, and electron paramagnetic resonance (EPR) results, we show that organisms from different environments ultilize one of four main IspH classes. The classes are based on the arrangement of the aromatic residues near the 4Fe-4S cluster and the presence or absence of N- and C-terminal extensions. Class A enzymes are found primarily in anaerobic and microaerophilic bacteria. Class B enzymes are found in aerobic bacteria. Class C enzymes are found in cyanobacteria and plants. Class D enzymes are found in apicomplexan parasites. Using mutagenesis, we show that the cluster-associated aromatic groups in class A and class B IspHs enhance cluster oxidative stability. Y198A, F302A, and a C-terminal truncation mutant of the class B (Escherichia coli) IspH have catalytic activity lower than that of the wild-type protein when using methyl viologen as the electron donor, but higher activity with dithionite as the electron donor, due to ready access of the small reductant to the cluster, consistent with their increased oxygen and H2O2 sensitivity. F302A has the largest effect on the reaction rates, and EPR studies indicate this residue affects Fe-S cluster structure. Similar effects on cluster stability are seen with class A (F14A and Y98A) mutants; however, effects on ET rates are smaller, and there are no differences between the EPR spectra of mutant and wild-type proteins. Overall, the results are of general interest because they show, for the first time, that there are multiple IspH classes that have evolved to allow organisms to survive in diverse oxidative-stress environments. PMID:27357244

  10. The O2 sensitivity of the transcription factor FNR is controlled by Ser24 modulating the kinetics of [4Fe-4S] to [2Fe-2S] conversion.

    PubMed

    Jervis, Adrian J; Crack, Jason C; White, Gaye; Artymiuk, Peter J; Cheesman, Myles R; Thomson, Andrew J; Le Brun, Nick E; Green, Jeffrey

    2009-03-24

    Fumarate and nitrate reduction regulatory (FNR) proteins are bacterial transcription factors that coordinate the switch between aerobic and anaerobic metabolism. In the absence of O(2), FNR binds a [4Fe-4S](2+) cluster (ligated by Cys-20, 23, 29, 122) promoting the formation of a transcriptionally active dimer. In the presence of O(2), FNR is converted into a monomeric, non-DNA-binding form containing a [2Fe-2S](2+) cluster. The reaction of the [4Fe-4S](2+) cluster with O(2) has been shown to proceed via a 2-step process, an O(2)-dependent 1-electron oxidation to yield a [3Fe-4S](+) intermediate with release of 1 Fe(2+) ion, followed by spontaneous rearrangement to the [2Fe-2S](2+) form with release of 1 Fe(3+) and 2 S(2-) ions. Here, we show that replacement of Ser-24 by Arg, His, Phe, Trp, or Tyr enhances aerobic activity of FNR in vivo. The FNR-S24F protein incorporates a [4Fe-4S](2+) cluster with spectroscopic properties similar to those of FNR. However, the substitution enhances the stability of the [4Fe-4S](2+) cluster in the presence of O(2). Kinetic analysis shows that both steps 1 and 2 are slower for FNR-S24F than for FNR. A molecular model suggests that step 1 of the FNR-S24F iron-sulfur cluster reaction with O(2) is inhibited by shielding of the iron ligand Cys-23, suggesting that Cys-23 or the cluster iron bound to it is a primary site of O(2) interaction. These data lead to a simple model of the FNR switch with physiological implications for the ability of FNR proteins to operate over different ranges of in vivo O(2) concentrations. PMID:19261852

  11. Cloning, expression, and molecular characterization of the gene encoding an extremely thermostable [4Fe-4S] ferredoxin from the hyperthermophilic archaeon Pyrococcus furiosus.

    PubMed Central

    Heltzel, A; Smith, E T; Zhou, Z H; Blamey, J M; Adams, M W

    1994-01-01

    The gene for ferredoxin from the hyperthermophilic archaeon Pyrococcus furiosus was cloned, sequenced, and expressed in Escherichia coli. The coding region confirmed the determined amino acid sequence. Putative archaeon-type transcriptional regulatory elements were identified. The fdxA gene appears to be an independent transcriptional unit. Recombinant ferredoxin was indistinguishable from the protein purified from P. furiosus in its thermal stability and in the potentiometric and spectroscopic properties of its [4Fe-4S] cluster. PMID:8045914

  12. Sequence determination of reduction potentials by cysteinyl hydrogen bonds and peptide pipoles in [4Fe-4S] ferredoxins.

    PubMed Central

    Beck, B W; Xie, Q; Ichiye, T

    2001-01-01

    A sequence determinant of reduction potentials is reported for bacterial [4Fe-4S]-type ferredoxins. The residue that is four residues C-terminal to the fourth ligand of either cluster is generally an alanine or a cysteine. In five experimental ferredoxin structures, the cysteine has the same structural orientation relative to the nearest cluster, which is stabilized by the SH...S bond. Although such bonds are generally considered weak, indications that Fe-S redox site sulfurs are better hydrogen-bond acceptors than most sulfurs include the numerous amide NH...S bonds noted by Adman and our quantum mechanical calculations. Furthermore, electrostatic potential calculations of 11 experimental ferredoxin structures indicate that the extra cysteine decreases the reduction potential relative to an alanine by approximately 60 mV, in agreement with experimental mutational studies. Moreover, the decrease in potential is due to a shift in the polar backbone stabilized by the SH...S bond rather than to the slightly polar cysteinyl side chain. Thus, these cysteines can "tune" the reduction potential, which could optimize electron flow in an electron transport chain. More generally, hydrogen bonds involving sulfur can be important in protein structure/function, and mutations causing polar backbone shifts can alter electrostatics and thus affect redox properties or even enzymatic activity of a protein. PMID:11463610

  13. Heterologous overproduction of 2[4Fe4S]- and [2Fe2S]-type clostridial ferredoxins and [2Fe2S]-type agrobacterial ferredoxin.

    PubMed

    Huang, Haiyan; Hu, Liejie; Yu, Wenjun; Li, Huili; Tao, Fei; Xie, Huijun; Wang, Shuning

    2016-05-01

    Ferredoxins are small, acidic proteins containing iron-sulfur clusters that are widespread in living organisms. They play key roles as electron carriers in various metabolic processes, including respiration, photosynthesis, fermentation, nitrogen fixation, carbon dioxide fixation, and hydrogen production. However, only several kinds of ferredoxins are commercially available now, greatly limiting the investigation of ferredoxin-related enzymes and metabolic processes. Here we describe the heterologous overproduction of 2[4Fe4S]- and [2Fe2S]-type clostridial ferredoxins and [2Fe2S]-type agrobacterial ferredoxin. Adding extra iron and sulfur sources to the medium in combination with using Escherichia coli C41(DE3) harboring pCodonplus and pRKISC plasmids as host greatly enhanced iron-sulfur cluster synthesis in the three ferredoxins. After induction for 12 h in terrific broth and purification by affinity chromatography and anion exchange chromatography, approximately 3.4 mg of streptavidin (Strep)-tagged and 3.7 mg of polyhistidine (His)-tagged clostridial 2[4Fe4S] ferredoxins were obtained from 1 l of culture. Excitingly, after induction for 24 h in terrific broth, around 40 mg of His-tagged clostridial [2Fe2S] and 23 mg of His-tagged agrobacterial [2Fe2S] ferredoxins were purified from 1 l of culture. The recombinant ferredoxins apparently exhibited identical properties and physiological function to native ferredoxins. No negative impact of two different affinity tags on ferredoxin activity was found. In conclusion, we successfully developed a convenient method for heterologous overproduction of the three kinds of ferredoxins with satisfactory yields and activities, which would be very helpful for the ferredoxin-related researches. PMID:26748213

  14. Structural principles for computational and de novo design of 4Fe-4S metalloproteins.

    PubMed

    Nanda, Vikas; Senn, Stefan; Pike, Douglas H; Rodriguez-Granillo, Agustina; Hansen, Will A; Khare, Sagar D; Noy, Dror

    2016-05-01

    Iron-sulfur centers in metalloproteins can access multiple oxidation states over a broad range of potentials, allowing them to participate in a variety of electron transfer reactions and serving as catalysts for high-energy redox processes. The nitrogenase FeMoCO cluster converts di-nitrogen to ammonia in an eight-electron transfer step. The 2(Fe4S4) containing bacterial ferredoxin is an evolutionarily ancient metalloprotein fold and is thought to be a primordial progenitor of extant oxidoreductases. Controlling chemical transformations mediated by iron-sulfur centers such as nitrogen fixation, hydrogen production as well as electron transfer reactions involved in photosynthesis are of tremendous importance for sustainable chemistry and energy production initiatives. As such, there is significant interest in the design of iron-sulfur proteins as minimal models to gain fundamental understanding of complex natural systems and as lead-molecules for industrial and energy applications. Herein, we discuss salient structural characteristics of natural iron-sulfur proteins and how they guide principles for design. Model structures of past designs are analyzed in the context of these principles and potential directions for enhanced designs are presented, and new areas of iron-sulfur protein design are proposed. This article is part of a Special issue entitled Biodesign for Bioenergetics--the design and engineering of electronic transfer cofactors, protein networks, edited by Ronald L. Koder and J.L Ross Anderson.

  15. Structural principles for computational and de novo design of 4Fe-4S metalloproteins.

    PubMed

    Nanda, Vikas; Senn, Stefan; Pike, Douglas H; Rodriguez-Granillo, Agustina; Hansen, Will A; Khare, Sagar D; Noy, Dror

    2016-05-01

    Iron-sulfur centers in metalloproteins can access multiple oxidation states over a broad range of potentials, allowing them to participate in a variety of electron transfer reactions and serving as catalysts for high-energy redox processes. The nitrogenase FeMoCO cluster converts di-nitrogen to ammonia in an eight-electron transfer step. The 2(Fe4S4) containing bacterial ferredoxin is an evolutionarily ancient metalloprotein fold and is thought to be a primordial progenitor of extant oxidoreductases. Controlling chemical transformations mediated by iron-sulfur centers such as nitrogen fixation, hydrogen production as well as electron transfer reactions involved in photosynthesis are of tremendous importance for sustainable chemistry and energy production initiatives. As such, there is significant interest in the design of iron-sulfur proteins as minimal models to gain fundamental understanding of complex natural systems and as lead-molecules for industrial and energy applications. Herein, we discuss salient structural characteristics of natural iron-sulfur proteins and how they guide principles for design. Model structures of past designs are analyzed in the context of these principles and potential directions for enhanced designs are presented, and new areas of iron-sulfur protein design are proposed. This article is part of a Special issue entitled Biodesign for Bioenergetics--the design and engineering of electronic transfer cofactors, protein networks, edited by Ronald L. Koder and J.L Ross Anderson. PMID:26449207

  16. Direct measurement of the hydrogen-bonding effect on the intrinsic redox potentials of [4Fe-4S] cubane complexes.

    PubMed

    Yang, Xin; Niu, Shuqiang; Ichiye, Toshiko; Wang, Lai-Sheng

    2004-12-01

    To probe how H-bonding effects the redox potential changes in Fe-S proteins, we produced and studied a series of gaseous cubane-type analogue complexes, [Fe(4)S(4)(SEt)(3)(SC(n)H(2n+1))](2-) and [Fe(4)S(4)(SEt)(3)(SC(n)H(2n)OH)](2-) (n = 4, 6, 11; Et = C(2)H(5)). Intrinsic redox potentials for the [Fe(4)S(4)](2+/3+) redox couple involved in these complexes were measured by photoelectron spectroscopy. The oxidation energies from [Fe(4)S(4)(SEt)(3)(SC(n)H(2n)OH)](2-) to [Fe(4)S(4)(SEt)(3)(SC(n)H(2n)OH)](-) were determined directly from the photoelectron spectra to be approximately 130 meV higher than those for the corresponding [Fe(4)S(4)(SEt)(3)(SC(n)H(2n+1))](2-) systems, because of the OH...S hydrogen bond in the former. Preliminary Monte Carlo and density functional calculations showed that the H-bonding takes place between the -OH group and the S on the terminal ligand in [Fe(4)S(4)(SEt)(3)(SC(6)H(12)OH)](2-). The current data provide a direct experimental measure of a net H-bonding effect on the redox potential of [Fe(4)S(4)] clusters without the perturbation of other environmental effects.

  17. Clustering PPI data by combining FA and SHC method

    PubMed Central

    2015-01-01

    Clustering is one of main methods to identify functional modules from protein-protein interaction (PPI) data. Nevertheless traditional clustering methods may not be effective for clustering PPI data. In this paper, we proposed a novel method for clustering PPI data by combining firefly algorithm (FA) and synchronization-based hierarchical clustering (SHC) algorithm. Firstly, the PPI data are preprocessed via spectral clustering (SC) which transforms the high-dimensional similarity matrix into a low dimension matrix. Then the SHC algorithm is used to perform clustering. In SHC algorithm, hierarchical clustering is achieved by enlarging the neighborhood radius of synchronized objects continuously, while the hierarchical search is very difficult to find the optimal neighborhood radius of synchronization and the efficiency is not high. So we adopt the firefly algorithm to determine the optimal threshold of the neighborhood radius of synchronization automatically. The proposed algorithm is tested on the MIPS PPI dataset. The results show that our proposed algorithm is better than the traditional algorithms in precision, recall and f-measure value. PMID:25707632

  18. A T14C variant of Azotobacter vinelandii ferredoxin I undergoes facile [3Fe-4S]0 to [4Fe-4S]2+ conversion in vitro but not in vivo.

    PubMed

    Gao-Sheridan, H S; Kemper, M A; Khayat, R; Tilley, G J; Armstrong, F A; Sridhar, V; Prasad, G S; Stout, C D; Burgess, B K

    1998-12-11

    [4Fe-4S]2+/+ clusters that are ligated by Cys-X-X-Cys-X-X-Cys sequence motifs share the general feature of being hard to convert to [3Fe-4S]+/0 clusters, whereas those that contain a Cys-X-X-Asp-X-X-Cys motif undergo facile and reversible cluster interconversion. Little is known about the factors that control the in vivo assembly and conversion of these clusters. In this study we have designed and constructed a 3Fe to 4Fe cluster conversion variant of Azotobacter vinelandii ferredoxin I (FdI) in which the sequence that ligates the [3Fe-4S] cluster in native FdI was altered by converting a nearby residue, Thr-14, to Cys. Spectroscopic and electrochemical characterization shows that when purified in the presence of dithionite, T14C FdI is an O2-sensitive 8Fe protein. Both the new and the indigenous clusters have reduction potentials that are significantly shifted compared with those in native FdI, strongly suggesting a significantly altered environment around the clusters. Interestingly, whole cell EPR have revealed that T14C FdI exists as a 7Fe protein in vivo. This 7Fe form of T14C FdI is extremely similar to native FdI in its spectroscopic, electrochemical, and structural features. However, unlike native FdI which does not undergo facile cluster conversion, the 7Fe form T14C FdI quickly converts to the 8Fe form with a high efficiency under reducing conditions.

  19. Probing The Electronic Structure of Fe-S Clusters: Ubiquitous Electron Transfer Centers in Metalloproteins Using Anion Photoelectron Spectroscopy in the Gas Phase

    SciTech Connect

    Yang, Xin; Wang, Xue B.; FU, You-Jun; Wang, Lai S.

    2006-10-06

    Iron-Sulfur clusters are found in all forms of life, which constitute the active sites of a growing list of proteins in such essential life-sustaining processes as respiration, nitrogen fixation, and photosynthesis (Spiro 1982). The most prototypical and ubiquitous Fe-S cluster is the cubane-type [4Fe-4S] cluster, which, in addition to its catalytic and regulatory roles, appears to be nature’s favorite agent for electron transfer and storage, such as in ferrodoxins (Fds), high-potential iron proteins (HiPIPs), and the integral machineries of hydrogenases and nitrogenases (Bernnert et al. 1997; Einsle etal. 2002; Peters et al. 1998). In proteins, the cubane [4Fe-4S] unit is usually coordinated by the amino acid cysteine. The [4Fe-4S] core functions as electron transfer agent usually between the following oxidation states: [4Fe-4S]1+ ↔ [4Fe-4S]2+ ↔ [4Fe-4S]3+ . A fourth state, the all-ferrous species [4Fe-4S]0, was also detected in the iron protein of nitrogenase.

  20. Orientations of Iron-Sulfur Clusters FA and FB in the Homodimeric Type-I Photosynthetic Reaction Center of Heliobacterium modesticaldum.

    PubMed

    Kondo, Toru; Matsuoka, Masahiro; Azai, Chihiro; Itoh, Shigeru; Oh-Oka, Hirozo

    2016-05-12

    Orientations of the FA and FB iron-sulfur (FeS) clusters in a structure-unknown type-I homodimeric heriobacterial reaction center (hRC) were studied in oriented membranes of the thermophilic anaerobic photosynthetic bacterium Heliobacterium modesticaldum by electron paramagnetic resonance (EPR), and compared with those in heterodimeric photosystem I (PS I). The Rieske-type FeS center in the cytochrome b/c complex showed a well-oriented EPR signal. Illumination at 14 K induced an FB(-) signal with g-axes of gz = 2.066, gy = 1.937, and gx = 1.890, tilted at angles of 60°, 60°, and 45°, respectively, with respect to the membrane normal. Chemical reduction with dithionite produced an additional signal of FA(-), which magnetically interacted with FB(-), with gz = 2.046, gy = 1.942, and gx = 1.911 at 30°, 60°, and 90°, respectively. The angles and redox properties of FA(-) and FB(-) in hRC resemble those of FB(-) and FA(-), respectively, in PS I. Therefore, FA and FB in hRC, named after their g-value similarities, seem to be located like FB and FA, not like FA and FB, respectively, in PS I. The reducing side of hRC could resemble those in PS I, if the names of FA and FB are interchanged with each other.

  1. Spectroscopic and functional characterization of iron-sulfur cluster-bound forms of Azotobacter vinelandii (Nif)IscA.

    PubMed

    Mapolelo, Daphne T; Zhang, Bo; Naik, Sunil G; Huynh, Boi Hanh; Johnson, Michael K

    2012-10-16

    The mechanism of [4Fe-4S] cluster assembly on A-type Fe-S cluster assembly proteins, in general, and the specific role of (Nif)IscA in the maturation of nitrogen fixation proteins are currently unknown. To address these questions, in vitro spectroscopic studies (UV-visible absorption/CD, resonance Raman and Mössbauer) have been used to investigate the mechanism of [4Fe-4S] cluster assembly on Azotobacter vinelandii(Nif)IscA, and the ability of (Nif)IscA to accept clusters from NifU and to donate clusters to the apo form of the nitrogenase Fe-protein. The results show that (Nif)IscA can rapidly and reversibly cycle between forms containing one [2Fe-2S](2+) and one [4Fe-4S](2+) cluster per homodimer via DTT-induced two-electron reductive coupling of two [2Fe-2S](2+) clusters and O(2)-induced [4Fe-4S](2+) oxidative cleavage. This unique type of cluster interconversion in response to cellular redox status and oxygen levels is likely to be important for the specific role of A-type proteins in the maturation of [4Fe-4S] cluster-containing proteins under aerobic growth or oxidative stress conditions. Only the [4Fe-4S](2+)-(Nif)IscA was competent for rapid activation of apo-nitrogenase Fe protein under anaerobic conditions. Apo-(Nif)IscA was shown to accept clusters from [4Fe-4S] cluster-bound NifU via rapid intact cluster transfer, indicating a potential role as a cluster carrier for delivery of clusters assembled on NifU. Overall the results support the proposal that A-type proteins can function as carrier proteins for clusters assembled on U-type proteins and suggest that they are likely to supply [2Fe-2S] clusters rather than [4Fe-4S] for the maturation of [4Fe-4S] cluster-containing proteins under aerobic or oxidative stress growth conditions.

  2. Characterization of the iron-sulfur clusters in ferredoxin from acetate-grown Methanosarcina thermophila.

    PubMed Central

    Clements, A P; Kilpatrick, L; Lu, W P; Ragsdale, S W; Ferry, J G

    1994-01-01

    Ferredoxin from Methanosarcina thermophila is an electron acceptor for the CO dehydrogenase complex which decarbonylates acetyl-coenzyme A and oxidizes the carbonyl group to carbon dioxide in the pathway for conversion of the methyl group of acetate to methane (K. C. Terlesky and J. G. Ferry, J. Biol. Chem. 263:4080-4082, 1988). Resonance Raman spectroscopy and electron paramagnetic resonance spectroelectrochemistry indicated that the ferredoxin contained two [4Fe-4S] clusters per monomer of 6,790 Da, each with a midpoint potential of -407 mV. A [3Fe-4S] species, with a midpoint potential of +103 mV, was also detected in the protein at high redox potentials. Quantitation of the [3Fe-4S] and [4Fe-4S] centers revealed 0.4 and 2.1 spins per monomer, respectively. The iron-sulfur clusters were unstable in the presence of air, and the rate of cluster loss increased with increasing temperature. A ferredoxin preparation, with a low spin quantitation of [4Fe-4S] centers, was treated with Fe2+ and S2-, which resulted in an increase in [4Fe-4S] and a decrease in [3Fe-4S] clusters. The results of these studies suggest the [3Fe-4S] species may be an artifact formed from degradation of [4Fe-4S] clusters. PMID:8169218

  3. Active photosynthesis in cyanobacterial mutants with directed modifications in the ligands for two iron-sulfur clusters on the PsaC protein of photosystem I.

    PubMed Central

    Mannan, R M; He, W Z; Metzger, S U; Whitmarsh, J; Malkin, R; Pakrasi, H B

    1996-01-01

    The PsaC protein of the Photosystem I (PSI) complex in thylakoid membranes coordinates two [4Fe-4S] clusters, FA and FB. Although it is known that PsaC participates in electron transfer to ferredoxin, the pathway of electrons through this protein is unknown. To elucidate the roles of FA and FB, we created two site-directed mutant strains of the cyanobacterium Anabaena variabilis ATCC 29413. In one mutant, cysteine 13, a ligand for FB was replaced by an aspartic acid (C13D); in the other mutant, cysteine 50, a ligand for FA was modified similarly (C50D). Low-temperature electron paramagnetic resonance studies demonstrated that the C50D mutant has a normal FB center and a modified FA center. In contrast, the C13D strain has normal FA, but failed to reveal any signal from FB. Room-temperature optical studies showed that C13D has only one functional electron acceptor in PsaC, whereas two such acceptors are functional in the C50D and wild-type strains. Although both mutants grow under photoautotrophic conditions, the rate of PSI-mediated electron transfer in C13D under low light levels is about half that of C50D or wild type. These data show that (i) FB is not essential for the assembly of the PsaC protein in PSI and (ii) FB is not absolutely required for electron transfer from the PSI reaction center to ferredoxin. PMID:8617228

  4. Role of Nfu1 and Bol3 in iron-sulfur cluster transfer to mitochondrial clients.

    PubMed

    Melber, Andrew; Na, Un; Vashisht, Ajay; Weiler, Benjamin D; Lill, Roland; Wohlschlegel, James A; Winge, Dennis R

    2016-01-01

    Iron-sulfur (Fe-S) clusters are essential for many cellular processes, ranging from aerobic respiration, metabolite biosynthesis, ribosome assembly and DNA repair. Mutations in NFU1 and BOLA3 have been linked to genetic diseases with defects in mitochondrial Fe-S centers. Through genetic studies in yeast, we demonstrate that Nfu1 functions in a late step of [4Fe-4S] cluster biogenesis that is of heightened importance during oxidative metabolism. Proteomic studies revealed Nfu1 physical interacts with components of the ISA [4Fe-4S] assembly complex and client proteins that need [4Fe-4S] clusters to function. Additional studies focused on the mitochondrial BolA proteins, Bol1 and Bol3 (yeast homolog to human BOLA3), revealing that Bol1 functions earlier in Fe-S biogenesis with the monothiol glutaredoxin, Grx5, and Bol3 functions late with Nfu1. Given these observations, we propose that Nfu1, assisted by Bol3, functions to facilitate Fe-S transfer from the biosynthetic apparatus to the client proteins preventing oxidative damage to [4Fe-4S] clusters. PMID:27532773

  5. Role of Nfu1 and Bol3 in iron-sulfur cluster transfer to mitochondrial clients

    PubMed Central

    Melber, Andrew; Na, Un; Vashisht, Ajay; Weiler, Benjamin D; Lill, Roland; Wohlschlegel, James A; Winge, Dennis R

    2016-01-01

    Iron-sulfur (Fe-S) clusters are essential for many cellular processes, ranging from aerobic respiration, metabolite biosynthesis, ribosome assembly and DNA repair. Mutations in NFU1 and BOLA3 have been linked to genetic diseases with defects in mitochondrial Fe-S centers. Through genetic studies in yeast, we demonstrate that Nfu1 functions in a late step of [4Fe-4S] cluster biogenesis that is of heightened importance during oxidative metabolism. Proteomic studies revealed Nfu1 physical interacts with components of the ISA [4Fe-4S] assembly complex and client proteins that need [4Fe-4S] clusters to function. Additional studies focused on the mitochondrial BolA proteins, Bol1 and Bol3 (yeast homolog to human BOLA3), revealing that Bol1 functions earlier in Fe-S biogenesis with the monothiol glutaredoxin, Grx5, and Bol3 functions late with Nfu1. Given these observations, we propose that Nfu1, assisted by Bol3, functions to facilitate Fe-S transfer from the biosynthetic apparatus to the client proteins preventing oxidative damage to [4Fe-4S] clusters. DOI: http://dx.doi.org/10.7554/eLife.15991.001 PMID:27532773

  6. Role of Nfu1 and Bol3 in iron-sulfur cluster transfer to mitochondrial clients.

    PubMed

    Melber, Andrew; Na, Un; Vashisht, Ajay; Weiler, Benjamin D; Lill, Roland; Wohlschlegel, James A; Winge, Dennis R

    2016-08-17

    Iron-sulfur (Fe-S) clusters are essential for many cellular processes, ranging from aerobic respiration, metabolite biosynthesis, ribosome assembly and DNA repair. Mutations in NFU1 and BOLA3 have been linked to genetic diseases with defects in mitochondrial Fe-S centers. Through genetic studies in yeast, we demonstrate that Nfu1 functions in a late step of [4Fe-4S] cluster biogenesis that is of heightened importance during oxidative metabolism. Proteomic studies revealed Nfu1 physical interacts with components of the ISA [4Fe-4S] assembly complex and client proteins that need [4Fe-4S] clusters to function. Additional studies focused on the mitochondrial BolA proteins, Bol1 and Bol3 (yeast homolog to human BOLA3), revealing that Bol1 functions earlier in Fe-S biogenesis with the monothiol glutaredoxin, Grx5, and Bol3 functions late with Nfu1. Given these observations, we propose that Nfu1, assisted by Bol3, functions to facilitate Fe-S transfer from the biosynthetic apparatus to the client proteins preventing oxidative damage to [4Fe-4S] clusters.

  7. Characterization of a unique [FeS] cluster in the electron transfer chain of the oxygen tolerant [NiFe] hydrogenase from Aquifex aeolicus.

    PubMed

    Pandelia, Maria-Eirini; Nitschke, Wolfgang; Infossi, Pascale; Giudici-Orticoni, Marie-Thérèse; Bill, Eckhard; Lubitz, Wolfgang

    2011-04-12

    Iron-sulfur clusters are versatile electron transfer cofactors, ubiquitous in metalloenzymes such as hydrogenases. In the oxygen-tolerant Hydrogenase I from Aquifex aeolicus such electron "wires" form a relay to a diheme cytb, an integral part of a respiration pathway for the reduction of O(2) to water. Amino acid sequence comparison with oxygen-sensitive hydrogenases showed conserved binding motifs for three iron-sulfur clusters, the nature and properties of which were unknown so far. Electron paramagnetic resonance spectra exhibited complex signals that disclose interesting features and spin-coupling patterns; by redox titrations three iron-sulfur clusters were identified in their usual redox states, a [3Fe4S] and two [4Fe4S], but also a unique high-potential (HP) state was found. On the basis of (57)Fe Mössbauer spectroscopy we attribute this HP form to a superoxidized state of the [4Fe4S] center proximal to the [NiFe] site. The unique environment of this cluster, characterized by a surplus cysteine coordination, is able to tune the redox potentials and make it compliant with the [4Fe4S](3+) state. It is actually the first example of a biological [4Fe4S] center that physiologically switches between 3+, 2+, and 1+ oxidation states within a very small potential range. We suggest that the (1 + /2+) redox couple serves the classical electron transfer reaction, whereas the superoxidation step is associated with a redox switch against oxidative stress.

  8. New redox states observed in [FeFe] hydrogenases reveal redox coupling within the H-cluster.

    PubMed

    Adamska-Venkatesh, Agnieszka; Krawietz, Danuta; Siebel, Judith; Weber, Katharina; Happe, Thomas; Reijerse, Edward; Lubitz, Wolfgang

    2014-08-13

    Active [FeFe] hydrogenases can be obtained by expressing the unmaturated enzyme in Escherichia coli followed by incubation with a synthetic precursor of the binuclear [2Fe] subcluster, namely: [NEt4]2[Fe2(adt)(CO)4(CN)2] (adt = [S-CH2-NH-CH2-S](2-)). The binuclear subsite Fe2(adt)(CO)3(CN)2 is attached through a bridging cysteine side chain to a [4Fe-4S] subcluster already present in the unmaturated enzyme thus yielding the intact native "H-cluster". We present FTIR electrochemical studies of the [FeFe] hydrogenase from Chlamydomonas reinhardtii, CrHydA1, maturated with the precursor of the native cofactor [Fe2(adt)(CO)4(CN)2](2-) as well as a non-natural variant [Fe2(pdt)(CO)4(CN)2](2-) in which the bridging amine functionality is replaced by CH2. The obtained active enzyme CrHydA1(adt) shows the same redox states in the respective potential range as observed for the native system (E(ox/red) = -400 mV, E(red/sred) = -470 mV). For the Hox → Hred transition the reducing equivalent is stored on the binuclear part, ([4Fe-4S](2+)Fe(II)Fe(I) → [4Fe-4S](2+)Fe(I)Fe(I)), while the Hred → Hsred transition is characterized by a reduction of the [4Fe-4S] part of the H-cluster ([4Fe-4S](2+)Fe(I)Fe(I) → [4Fe-4S](+)Fe(I)Fe(I)). A similar transition is reported here for the CO inhibited state of the H-cluster: ([4Fe-4S](2+)Fe(I)Fe(II)CO → [4Fe-4S](+)Fe(I)Fe(II)CO). An FTIR electrochemical study of the inactive variant with the pdt ligand, CrHydA1(pdt), identified two redox states H(pdt)-ox and H(pdt)-"red". Both EPR and FTIR spectra of H(pdt)-ox are virtually identical to those of the H(adt)-ox and the native Hox state. The H(pdt)-"red" state is also characterized by a reduced [4Fe-4S] subcluster. In contrast to CrHydA1(adt), the H(pdt)-ox state of CrHydA1(pdt) is stable up to rather high potentials (+200 mV). This study demonstrates the distinct redox coupling between the two parts of the H-cluster and confirms that the [4Fe-4S]H subsite is also redox active and as

  9. The role and properties of the iron-sulfur cluster in Escherichia coli dihydroxy-acid dehydratase.

    PubMed

    Flint, D H; Emptage, M H; Finnegan, M G; Fu, W; Johnson, M K

    1993-07-15

    Dihydroxy-acid dehydratase has been purified from Escherichia coli and characterized as a homodimer with a subunit molecular weight of 66,000. The combination of UV visible absorption, EPR, magnetic circular dichroism, and resonance Raman spectroscopies indicates that the native enzyme contains a [4Fe-4S]2+,+ cluster, in contrast to spinach dihydroxy-acid dehydratase which contains a [2Fe-2S]2+,+ cluster (Flint, D. H., and Emptage, M. H. (1988) J. Biol. Chem. 263, 3558-3564). In frozen solution, the reduced [4Fe-4S]+ cluster has a S = 3/2 ground state with minor contributions from forms with S = 1/2 and possibly S = 5/2 ground states. Resonance Raman studies of the [4Fe-4S]2+ cluster in E. coli dihydroxy-acid dehydratase indicate non-cysteinyl coordination of a specific iron, which suggests that it is likely to be directly involved in catalysis as is the case with aconitase (Emptage, M. H., Kent, T. A., Kennedy, M. C., Beinert, H., and Münck, E. (1983) Proc. Natl. Acad. Sci. U.S.A. 80, 4674-4678). Dihydroxy-acid dehydratase from E. coli is inactivated by O2 in vitro and in vivo as a result of oxidative degradation of the [4Fe-4S]cluster. Compared to aconitase, the oxidized cluster of E. coli dihydroxy-acid dehydratase appears to be less stable as either a cubic or linear [3Fe-4S] cluster or a [2Fe-2S] cluster. Oxidative degradation appears to lead to a complete breakdown of the Fe-S cluster, and the resulting protein cannot be reactivated with Fe2+ and thiol reducing agents.

  10. FA-SIFT study of reactions of protonated water and ethanol clusters with [alpha]-pinene and linalool in view of their selective detection by CIMS

    NASA Astrophysics Data System (ADS)

    Dhooghe, F.; Amelynck, C.; Rimetz-Planchon, J.; Schoon, N.; Vanhaecke, F.

    2010-02-01

    The use of protonated water clusters and protonated ethanol clusters as reagent ions has been evaluated for the resolution of an interference encountered in CIMS when measuring monoterpenes (C10H16) and linalool (C10H18O) simultaneously. To this end, the reactions of H3O+.(H2O)n (n = 1-3), (C2H5OH)mH+ (m = 1-3) and (C2H5OH.H2O)H+ with [alpha]-pinene and linalool have been characterized in a flowing afterglow-selected ion flow tube (FA-SIFT) instrument at a SIFT He buffer gas pressure of 1.43 hPa and a temperature of 298 K. All reactions with linalool were found to occur at the collision limit. The reaction of (C2H5OH)2H+ with [alpha]-pinene proceeds at half the collision rate and both the reactions of (C2H5OH)3H+ and H3O+.(H2O)3 with [alpha]-pinene have a very low rate constant. All other reactions involving [alpha]-pinene proceed at the collision rate. The reactions of H3O+.H2O, H3O+.(H2O)2, C2H5OH2+, (C2H5OH.H2O)H+ and (C2H5OH)2H+ with [alpha]-pinene mainly proceed by proton transfer. Additionally, ligand switching channels have been observed for the reactions of (C2H5OH)2H+ and H3O+.(H2O)2 with [alpha]-pinene. Protonated linalool was observed as a minor product for the reactions of (C2H5OH.H2O)H+ and H3O+.(H2O)n (n = 1-3) with linalool. For all linalool reactions, a contribution of the dissociative proton transfer product at m/z 137 was found and this ion was the main product ion for the reactions with H3O+.H2O, C2H5OH2+ and (C2H5OH.H2O)H+. For the (C2H5OH.H2O)H+/linalool reaction, ligand switching with both water and ethanol has been observed. Major ligand switching channels were observed for the reactions of (C2H5OH)2H+, (C2H5OH)3H+ and H3O+.(H2O)2 with linalool. Also, for the H3O+.(H2O)3/linalool reaction, several ligand switching channels have been observed. These results are discussed in view of their applicability for the selective detection of monoterpenes and linalool with CIMS instrumentation such as SIFT-MS, PTR-MS and APCI-MS.

  11. Pseudomonas aeruginosa IscR-Regulated Ferredoxin NADP(+) Reductase Gene (fprB) Functions in Iron-Sulfur Cluster Biogenesis and Multiple Stress Response.

    PubMed

    Romsang, Adisak; Duang-Nkern, Jintana; Wirathorn, Wilaiwan; Vattanaviboon, Paiboon; Mongkolsuk, Skorn

    2015-01-01

    P. aeruginosa (PAO1) has two putative genes encoding ferredoxin NADP(+) reductases, denoted fprA and fprB. Here, the regulation of fprB expression and the protein's physiological roles in [4Fe-4S] cluster biogenesis and stress protection are characterized. The fprB mutant has defects in [4Fe-4S] cluster biogenesis, as shown by reduced activities of [4Fe-4S] cluster-containing enzymes. Inactivation of the gene resulted in increased sensitivity to oxidative, thiol, osmotic and metal stresses compared with the PAO1 wild type. The increased sensitivity could be partially or completely suppressed by high expression of genes from the isc operon, which are involved in [Fe-S] cluster biogenesis, indicating that stress sensitivity in the fprB mutant is partially caused by a reduction in levels of [4Fe-4S] clusters. The pattern and regulation of fprB expression are in agreement with the gene physiological roles; fprB expression was highly induced by redox cycling drugs and diamide and was moderately induced by peroxides, an iron chelator and salt stress. The stress-induced expression of fprB was abolished by a deletion of the iscR gene. An IscR DNA-binding site close to fprB promoter elements was identified and confirmed by specific binding of purified IscR. Analysis of the regulation of fprB expression supports the role of IscR in directly regulating fprB transcription as a transcription activator. The combination of IscR-regulated expression of fprB and the fprB roles in response to multiple stressors emphasizes the importance of [Fe-S] cluster homeostasis in both gene regulation and stress protection.

  12. The FX iron-sulfur cluster serves as the terminal bound electron acceptor in heliobacterial reaction centers.

    PubMed

    Romberger, Steven P; Golbeck, John H

    2012-03-01

    Phototrophs of the family Heliobacteriaceae contain the simplest known Type I reaction center (RC), consisting of a homodimeric (PshA)(2) core devoid of bound cytochromes and antenna proteins. Unlike plant and cyanobacterial Photosystem I in which the F(A)/F(B) protein, PsaC, is tightly bound to P(700)-F(X) cores, the RCs of Heliobacterium modesticaldum contain two F(A)/F(B) proteins, PshBI and PshBII, which are loosely bound to P(800)-F(X) cores. These two 2[4Fe-4S] ferredoxins have been proposed to function as mobile redox proteins, reducing downstream metabolic partners much in the same manner as does [2Fe-2S] ferredoxin or flavodoxin (Fld) in PS I. Using P(800)-F(X) cores devoid of PshBI and PshBII, we show that iron-sulfur cluster F(X) directly reduces Fld without the involvement of F(A) or F(B) (Fld is used as a proxy for soluble redox proteins even though a gene encoding Fld is not identified in the H. modesticaldum genome). The reduction of Fld is suppressed by the addition of PshBI or PshBII, an effect explained by competition for the electron on F(X). In contrast, P(700)-F(X) cores require the presence of the PsaC, and hence, the F(A)/F(B) clusters for Fld (or ferredoxin) reduction. Thus, in H. modesticaldum, the interpolypeptide F(X) cluster serves as the terminal bound electron acceptor. This finding implies that the homodimeric (PshA)(2) cores should be capable of donating electrons to a wide variety of yet-to-be characterized soluble redox partners. PMID:22297911

  13. Crystal structure of an Fe-S cluster-containing fumarate hydratase enzyme from Leishmania major reveals a unique protein fold.

    PubMed

    Feliciano, Patricia R; Drennan, Catherine L; Nonato, M Cristina

    2016-08-30

    Fumarate hydratases (FHs) are essential metabolic enzymes grouped into two classes. Here, we present the crystal structure of a class I FH, the cytosolic FH from Leishmania major, which reveals a previously undiscovered protein fold that coordinates a catalytically essential [4Fe-4S] cluster. Our 2.05 Å resolution data further reveal a dimeric architecture for this FH that resembles a heart, with each lobe comprised of two domains that are arranged around the active site. Besides the active site, where the substrate S-malate is bound bidentate to the unique iron of the [4Fe-4S] cluster, other binding pockets are found near the dimeric enzyme interface, some of which are occupied by malonate, shown here to be a weak inhibitor of this enzyme. Taken together, these data provide a framework both for investigations of the class I FH catalytic mechanism and for drug design aimed at fighting neglected tropical diseases.

  14. Crystal structure of an Fe-S cluster-containing fumarate hydratase enzyme from Leishmania major reveals a unique protein fold.

    PubMed

    Feliciano, Patricia R; Drennan, Catherine L; Nonato, M Cristina

    2016-08-30

    Fumarate hydratases (FHs) are essential metabolic enzymes grouped into two classes. Here, we present the crystal structure of a class I FH, the cytosolic FH from Leishmania major, which reveals a previously undiscovered protein fold that coordinates a catalytically essential [4Fe-4S] cluster. Our 2.05 Å resolution data further reveal a dimeric architecture for this FH that resembles a heart, with each lobe comprised of two domains that are arranged around the active site. Besides the active site, where the substrate S-malate is bound bidentate to the unique iron of the [4Fe-4S] cluster, other binding pockets are found near the dimeric enzyme interface, some of which are occupied by malonate, shown here to be a weak inhibitor of this enzyme. Taken together, these data provide a framework both for investigations of the class I FH catalytic mechanism and for drug design aimed at fighting neglected tropical diseases. PMID:27528683

  15. Spectroscopic changes during a single turnover of biotin synthase: destruction of a [2Fe-2S] cluster accompanies sulfur insertion.

    PubMed

    Ugulava, N B; Sacanell, C J; Jarrett, J T

    2001-07-27

    Biotin synthase catalyzes the insertion of a sulfur atom between the saturated C6 and C9 carbons of dethiobiotin. Catalysis requires AdoMet and flavodoxin and generates 5'-deoxyadenosine and methionine, suggesting that biotin synthase is an AdoMet-dependent radical enzyme. Biotin synthase (BioB) is aerobically purified as a dimer of 38.4 kDa monomers that contains 1-1.5 [2Fe-2S](2+) clusters per monomer and can be reconstituted with exogenous iron, sulfide, and reductants to contain up to two [4Fe-4S] clusters per monomer. The iron-sulfur clusters may play a dual role in biotin synthase: a reduced iron-sulfur cluster is probably involved in radical generation by mediating the reductive cleavage of AdoMet, while recent in vitro labeling studies suggest that an iron-sulfur cluster also serves as the immediate source of sulfur for the biotin thioether ring. Consistent with this dual role for iron-sulfur clusters in biotin synthase, we have found that the protein is stable, containing one [2Fe-2S](2+) cluster and one [4Fe-4S](2+) cluster per monomer. In the present study, we demonstrate that this mixed cluster state is essential for optimal activity. We follow changes in the Fe and S content and UV/visible and EPR spectra of the enzyme during a single turnover and conclude that during catalysis the [4Fe-4S](2+) cluster is preserved while the [2Fe-2S](2+) cluster is destroyed. We propose a mechanism for incorporation of sulfur into dethiobiotin in which a sulfur atom is oxidatively extracted from the [2Fe-2S](2+) cluster. PMID:11444982

  16. The function and properties of the iron-sulfur center in spinach ferredoxin: thioredoxin reductase: a new biological role for iron-sulfur clusters.

    PubMed

    Staples, C R; Ameyibor, E; Fu, W; Gardet-Salvi, L; Stritt-Etter, A L; Schürmann, P; Knaff, D B; Johnson, M K

    1996-09-01

    Thioredoxin reduction in chloroplasts is catalyzed by a unique class of disulfide reductases which use a [2Fe-2S]2+/+ ferredoxin as the electron donor and contain an Fe-S cluster as the sole prosthetic group in addition to the active-site disulfide. The nature, properties, and function of the Fe-S cluster in spinach ferredoxin:thioredoxin reductase (FTR) have been investigated by the combination of UV/visible absorption, variable-temperature magnetic circular dichroism (MCD), EPR, and resonance Raman (RR) spectroscopies. The results indicate the presence of an S = 0 [4Fe-4S]2+ cluster with complete cysteinyl-S coordination that cannot be reduced at potentials down to -650 mV, but can be oxidized by ferricyanide to an S = 1/2 [4Fe-4S]3+ state (g = 2.09, 2.04, 2.02). The midpoint potential for the [4Fe-4S]3+/2+ couple is estimated to be +420 mV (versus NHE). These results argue against a role for the cluster in mediating electron transport from ferredoxin (Em = -420 mV) to the active-site disulfide (Em = -230 mV, n = 2). An alternative role for the cluster in stabilizing the one-electron-reduced intermediate is suggested by parallel spectroscopic studies of a modified form of the enzyme in which one of the cysteines of the active-site dithiol has been alkylated with N-ethylmaleimide (NEM). NEM-modified FTR is paramagnetic as prepared and exhibits a slow relaxing, S = 1/2 EPR signal, g = 2.11, 2.00, 1.98, that is observable without significant broadening up to 150 K. While the relaxation properties are characteristic of a radical species, MCD, RR, and absorption studies indicate at least partial cluster oxidation to the [4Fe-4S]3+ state. Dye-mediated EPR redox titrations indicate a midpoint potential of -210 mV for the one-electron reduction to a diamagnetic state. By analogy with the properties of the ferricyanide-oxidized [4Fe-4S] cluster in Azotobacter vinelandii 7Fe ferredoxin [Hu, Z., Jollie, D., Burgess, B. K., Stephens, P. J., & Münck, E. (1994) Biochemistry

  17. The Human Iron-Sulfur Assembly Complex Catalyzes the Synthesis of [2Fe-2S] Clusters on ISCU2 That Can Be Transferred to Acceptor Molecules.

    PubMed

    Fox, Nicholas G; Chakrabarti, Mrinmoy; McCormick, Sean P; Lindahl, Paul A; Barondeau, David P

    2015-06-30

    Iron-sulfur (Fe-S) clusters are essential protein cofactors for most life forms. In human mitochondria, the core Fe-S biosynthetic enzymatic complex (called SDUF) consists of NFS1, ISD11, ISCU2, and frataxin (FXN) protein components. Few mechanistic details about how this complex synthesizes Fe-S clusters and how these clusters are delivered to targets are known. Here circular dichroism and Mössbauer spectroscopies were used to reveal details of the Fe-S cluster assembly reaction on the SDUF complex. SDUF reactions generated [2Fe-2S] cluster intermediates that readily converted to stable [2Fe-2S] clusters bound to uncomplexed ISCU2. Similar reactions that included the apo Fe-S acceptor protein human ferredoxin (FDX1) resulted in formation of [2Fe-2S]-ISCU2 rather than [2Fe-2S]-FDX1. Subsequent addition of dithiothreitol (DTT) induced transfer of the cluster from ISCU2 to FDX1, suggesting that [2Fe-2S]-ISCU2 is an intermediate. Reactions that initially included DTT rapidly generated [2Fe-2S]-FDX1 and bypassed formation of [2Fe-2S]-ISCU2. In the absence of apo-FDX1, incubation of [2Fe-2S]-ISCU2 with DTT generated [4Fe-4S]-ISCU2 species. Together, these results conflict with a recent report of stable [4Fe-4S] cluster formation on the SDUF complex. Rather, they support a model in which SDUF builds transient [2Fe-2S] cluster intermediates that generate clusters on sulfur-containing molecules, including uncomplexed ISCU2. Additional small molecule or protein factors are required for the transfer of these clusters to Fe-S acceptor proteins or the synthesis of [4Fe-4S] clusters.

  18. Modulation of cluster incorporation specificity in a de novo iron-sulfur cluster binding peptide.

    PubMed

    Sommer, Dayn Joseph; Roy, Anindya; Astashkin, Andrei; Ghirlanda, Giovanna

    2015-07-01

    iron-sulfur cluster binding proteins perform an astounding variety of functions, and represent one of the most abundant classes of metalloproteins. Most often, they constitute pairs or chains and act as electron transfer modules either within complex redox enzymes or within small diffusible proteins. We have previously described the design of a three-helix bundle that can bind two clusters within its hydrophobic core. Here, we use single-point mutations to exchange one of the Cys ligands coordinating the cluster to either Leu or Ser. We show that the mutants modulate the redox potential of the clusters and stabilize the [3Fe-4S] form over the [4Fe-4S] form, supporting the use of model iron-sulfur cluster proteins as modules in the design of complex redox enzymes.

  19. X-ray crystallographic and EPR spectroscopic analysis of HydG, a maturase in [FeFe]-hydrogenase H-cluster assembly.

    PubMed

    Dinis, Pedro; Suess, Daniel L M; Fox, Stephen J; Harmer, Jenny E; Driesener, Rebecca C; De La Paz, Liliana; Swartz, James R; Essex, Jonathan W; Britt, R David; Roach, Peter L

    2015-02-01

    Hydrogenases use complex metal cofactors to catalyze the reversible formation of hydrogen. In [FeFe]-hydrogenases, the H-cluster cofactor includes a diiron subcluster containing azadithiolate, three CO, and two CN(-) ligands. During the assembly of the H cluster, the radical S-adenosyl methionine (SAM) enzyme HydG lyses the substrate tyrosine to yield the diatomic ligands. These diatomic products form an enzyme-bound Fe(CO)x(CN)y synthon that serves as a precursor for eventual H-cluster assembly. To further elucidate the mechanism of this complex reaction, we report the crystal structure and EPR analysis of HydG. At one end of the HydG (βα)8 triosephosphate isomerase (TIM) barrel, a canonical [4Fe-4S] cluster binds SAM in close proximity to the proposed tyrosine binding site. At the opposite end of the active-site cavity, the structure reveals the auxiliary Fe-S cluster in two states: one monomer contains a [4Fe-5S] cluster, and the other monomer contains a [5Fe-5S] cluster consisting of a [4Fe-4S] cubane bridged by a μ2-sulfide ion to a mononuclear Fe(2+) center. This fifth iron is held in place by a single highly conserved protein-derived ligand: histidine 265. EPR analysis confirms the presence of the [5Fe-5S] cluster, which on incubation with cyanide, undergoes loss of the labile iron to yield a [4Fe-4S] cluster. We hypothesize that the labile iron of the [5Fe-5S] cluster is the site of Fe(CO)x(CN)y synthon formation and that the limited bonding between this iron and HydG may facilitate transfer of the intact synthon to its cognate acceptor for subsequent H-cluster assembly.

  20. X-ray crystallographic and EPR spectroscopic analysis of HydG, a maturase in [FeFe]-hydrogenase H-cluster assembly

    PubMed Central

    Dinis, Pedro; Suess, Daniel L. M.; Fox, Stephen J.; Harmer, Jenny E.; Driesener, Rebecca C.; De La Paz, Liliana; Swartz, James R.; Essex, Jonathan W.; Britt, R. David; Roach, Peter L.

    2015-01-01

    Hydrogenases use complex metal cofactors to catalyze the reversible formation of hydrogen. In [FeFe]-hydrogenases, the H-cluster cofactor includes a diiron subcluster containing azadithiolate, three CO, and two CN− ligands. During the assembly of the H cluster, the radical S-adenosyl methionine (SAM) enzyme HydG lyses the substrate tyrosine to yield the diatomic ligands. These diatomic products form an enzyme-bound Fe(CO)x(CN)y synthon that serves as a precursor for eventual H-cluster assembly. To further elucidate the mechanism of this complex reaction, we report the crystal structure and EPR analysis of HydG. At one end of the HydG (βα)8 triosephosphate isomerase (TIM) barrel, a canonical [4Fe-4S] cluster binds SAM in close proximity to the proposed tyrosine binding site. At the opposite end of the active-site cavity, the structure reveals the auxiliary Fe-S cluster in two states: one monomer contains a [4Fe-5S] cluster, and the other monomer contains a [5Fe-5S] cluster consisting of a [4Fe-4S] cubane bridged by a μ2-sulfide ion to a mononuclear Fe2+ center. This fifth iron is held in place by a single highly conserved protein-derived ligand: histidine 265. EPR analysis confirms the presence of the [5Fe-5S] cluster, which on incubation with cyanide, undergoes loss of the labile iron to yield a [4Fe-4S] cluster. We hypothesize that the labile iron of the [5Fe-5S] cluster is the site of Fe(CO)x(CN)y synthon formation and that the limited bonding between this iron and HydG may facilitate transfer of the intact synthon to its cognate acceptor for subsequent H-cluster assembly. PMID:25605932

  1. Iron-sulfur cluster-dependent catalysis of chlorophyllide a oxidoreductase from Roseobacter denitrificans.

    PubMed

    Kiesel, Svenja; Wätzlich, Denise; Lange, Christiane; Reijerse, Edward; Bröcker, Markus J; Rüdiger, Wolfhart; Lubitz, Wolfgang; Scheer, Hugo; Moser, Jürgen; Jahn, Dieter

    2015-01-01

    Bacteriochlorophyll a biosynthesis requires the stereo- and regiospecific two electron reduction of the C7-C8 double bond of chlorophyllide a by the nitrogenase-like multisubunit metalloenzyme, chlorophyllide a oxidoreductase (COR). ATP-dependent COR catalysis requires interaction of the protein subcomplex (BchX)2 with the catalytic (BchY/BchZ)2 protein to facilitate substrate reduction via two redox active iron-sulfur centers. The ternary COR enzyme holocomplex comprising subunits BchX, BchY, and BchZ from the purple bacterium Roseobacter denitrificans was trapped in the presence of the ATP transition state analog ADP·AlF4(-). Electron paramagnetic resonance experiments revealed a [4Fe-4S] cluster of subcomplex (BchX)2. A second [4Fe-4S] cluster was identified on (BchY/BchZ)2. Mutagenesis experiments indicated that the latter is ligated by four cysteines, which is in contrast to the three cysteine/one aspartate ligation pattern of the closely related dark-operative protochlorophyllide a oxidoreductase (DPOR). In subsequent mutagenesis experiments a DPOR-like aspartate ligation pattern was implemented for the catalytic [4Fe-4S] cluster of COR. Artificial cluster formation for this inactive COR variant was demonstrated spectroscopically. A series of chemically modified substrate molecules with altered substituents on the individual pyrrole rings and the isocyclic ring were tested as COR substrates. The COR enzyme was still able to reduce the B ring of substrates carrying modified substituents on ring systems A, C, and E. However, substrates with a modification of the distantly located propionate side chain were not accepted. A tentative substrate binding mode was concluded in analogy to the related DPOR system.

  2. Bacterial iron-sulfur cluster sensors in mammalian pathogens

    PubMed Central

    Miller, Halie K.; Auerbuch, Victoria

    2015-01-01

    Iron-sulfur clusters act as important cofactors for a number of transcriptional regulators in bacteria, including many mammalian pathogens. The sensitivity of iron-sulfur clusters to iron availability, oxygen tension, and reactive oxygen and nitrogen species enables bacteria to use such regulators to adapt their gene expression profiles rapidly in response to changing environmental conditions. In this review, we discuss how the [4Fe-4S] or [2Fe-2S] cluster-containing regulators FNR, Wbl, aconitase, IscR, NsrR, SoxR, and AirSR contribute to bacterial pathogenesis through control of both metabolism and classical virulence factors. In addition, we briefly review mammalian iron homeostasis as well as oxidative/nitrosative stress to provide context for understanding the function of bacterial iron-sulfur cluster sensors in different niches within the host. PMID:25738802

  3. Bacterial iron-sulfur cluster sensors in mammalian pathogens.

    PubMed

    Miller, Halie K; Auerbuch, Victoria

    2015-06-01

    Iron-sulfur clusters act as important cofactors for a number of transcriptional regulators in bacteria, including many mammalian pathogens. The sensitivity of iron-sulfur clusters to iron availability, oxygen tension, and reactive oxygen and nitrogen species enables bacteria to use such regulators to adapt their gene expression profiles rapidly in response to changing environmental conditions. In this review, we discuss how the [4Fe-4S] or [2Fe-2S] cluster-containing regulators FNR, Wbl, aconitase, IscR, NsrR, SoxR, and AirSR contribute to bacterial pathogenesis through control of both metabolism and classical virulence factors. In addition, we briefly review mammalian iron homeostasis as well as oxidative/nitrosative stress to provide context for understanding the function of bacterial iron-sulfur cluster sensors in different niches within the host.

  4. Iron-sulfur clusters as biological sensors: the chemistry of reactions with molecular oxygen and nitric oxide.

    PubMed

    Crack, Jason C; Green, Jeffrey; Thomson, Andrew J; Le Brun, Nick E

    2014-10-21

    Iron-sulfur cluster proteins exhibit a range of physicochemical properties that underpin their functional diversity in biology, which includes roles in electron transfer, catalysis, and gene regulation. Transcriptional regulators that utilize iron-sulfur clusters are a growing group that exploit the redox and coordination properties of the clusters to act as sensors of environmental conditions including O2, oxidative and nitrosative stress, and metabolic nutritional status. To understand the mechanism by which a cluster detects such analytes and then generates modulation of DNA-binding affinity, we have undertaken a combined strategy of in vivo and in vitro studies of a range of regulators. In vitro studies of iron-sulfur cluster proteins are particularly challenging because of the inherent reactivity and fragility of the cluster, often necessitating strict anaerobic conditions for all manipulations. Nevertheless, and as discussed in this Account, significant progress has been made over the past decade in studies of O2-sensing by the fumarate and nitrate reduction (FNR) regulator and, more recently, nitric oxide (NO)-sensing by WhiB-like (Wbl) and FNR proteins. Escherichia coli FNR binds a [4Fe-4S] cluster under anaerobic conditions leading to a DNA-binding dimeric form. Exposure to O2 converts the cluster to a [2Fe-2S] form, leading to protein monomerization and hence loss of DNA binding ability. Spectroscopic and kinetic studies have shown that the conversion proceeds via at least two steps and involves a [3Fe-4S](1+) intermediate. The second step involves the release of two bridging sulfide ions from the cluster that, unusually, are not released into solution but rather undergo oxidation to sulfane (S(0)) subsequently forming cysteine persulfides that then coordinate the [2Fe-2S] cluster. Studies of other [4Fe-4S] cluster proteins that undergo oxidative cluster conversion indicate that persulfide formation and coordination may be more common than previously

  5. Silver(I), Mercury(II), Cadmium(II), and Zinc(II) Target Exposed Enzymic Iron-Sulfur Clusters when They Toxify Escherichia coli

    PubMed Central

    Xu, Fang Fang

    2012-01-01

    The toxicity of soft metals is of broad interest to microbiologists, both because such metals influence the community structures in natural environments and because several metals are used as antimicrobial agents. Their potency roughly parallels their thiophilicity, suggesting that their primary biological targets are likely to be enzymes that contain key sulfhydryl moieties. A recent study determined that copper poisons Escherichia coli in part by attacking the exposed [4Fe-4S] clusters of dehydratases. The present investigation sought to test whether other soft metals also target these enzymes. In vitro experiments revealed that low-micromolar concentrations of Ag(I) and Hg(II) directly inactivated purified fumarase A, a member of the dehydratase family. The enzyme was also poisoned by higher levels of Cd(II) and Zn(II), but it was unaffected by even millimolar concentrations of Mn(II), Co(II), Ni(II), and Pb(II). Electron paramagnetic resonance analysis and measurements of released iron confirmed that damage was associated with destruction of the [4Fe-4S] cluster, and indeed, the reconstruction of the cluster fully restored activity. Growth studies were then performed to test whether dehydratase damage might underlie toxicity in vivo. Barely toxic doses of Ag(I), Hg(II), Cd(II), and Zn(II) inactivated all tested members of the [4Fe-4S] dehydratase family. Again, activity was recovered when the clusters were rebuilt. The metals did not diminish the activities of other sampled enzymes, including NADH dehydrogenase I, an iron-sulfur protein whose clusters are shielded by polypeptide. Thus, the data indicate that dehydratases are damaged by the concentrations of metals that initiate bacteriostasis. PMID:22344668

  6. A Redox Active [2Fe-2S] Cluster on the Hydrogenase Maturase HydF.

    PubMed

    Shepard, Eric M; Byer, Amanda S; Betz, Jeremiah N; Peters, John W; Broderick, Joan B

    2016-06-28

    [FeFe]-hydrogenases are nature's most prolific hydrogen catalysts, excelling at facilely interconverting H2 and protons. The catalytic core common to all [FeFe]-hydrogenases is a complex metallocofactor, referred to as the H-cluster, which is composed of a standard [4Fe-4S] cluster linked through a bridging thiolate to a 2Fe subcluster harboring dithiomethylamine, carbon monoxide, and cyanide ligands. This 2Fe subcluster is synthesized and inserted into [FeFe]-hydrogenase by three maturase enzymes denoted HydE, HydF, and HydG. HydE and HydG are radical S-adenosylmethionine enzymes and synthesize the nonprotein ligands of the H-cluster. HydF is a GTPase that functions as a scaffold or carrier for 2Fe subcluster production. Herein, we utilize UV-visible, circular dichroism, and electron paramagnetic resonance spectroscopic studies to establish the existence of redox active [4Fe-4S] and [2Fe-2S] clusters bound to HydF. We have used spectroelectrochemical titrations to assign iron-sulfur cluster midpoint potentials, have shown that HydF purifies with a reduced [2Fe-2S] cluster in the absence of exogenous reducing agents, and have tracked iron-sulfur cluster spectroscopic changes with quaternary structural perturbations. Our results provide an important foundation for understanding the maturation process by defining the iron-sulfur cluster content of HydF prior to its interaction with HydE and HydG. We speculate that the [2Fe-2S] cluster of HydF either acts as a placeholder for HydG-derived Fe(CO)2CN species or serves as a scaffold for 2Fe subcluster assembly. PMID:27232385

  7. Electron Paramagnetic Resonance Characterization of Three Iron-Sulfur Clusters Present in the Nitrogenase Cofactor Maturase NifB from Methanocaldococcus infernus.

    PubMed

    Wilcoxen, Jarett; Arragain, Simon; Scandurra, Alessandro A; Jimenez-Vicente, Emilio; Echavarri-Erasun, Carlos; Pollmann, Stephan; Britt, R David; Rubio, Luis M

    2016-06-22

    NifB utilizes two equivalents of S-adenosyl methionine (SAM) to insert a carbide atom and fuse two substrate [Fe-S] clusters forming the NifB cofactor (NifB-co), which is then passed to NifEN for further modification to form the iron-molybdenum cofactor (FeMo-co) of nitrogenase. Here, we demonstrate that NifB from the methanogen Methanocaldococcus infernus is a radical SAM enzyme able to reductively cleave SAM to 5'-deoxyadenosine radical and is competent in FeMo-co maturation. Using electron paramagnetic resonance spectroscopy we have characterized three [4Fe-4S] clusters, one SAM binding cluster, and two auxiliary clusters probably acting as substrates for NifB-co formation. Nitrogen coordination to one or more of the auxiliary clusters in NifB was observed, and its mechanistic implications for NifB-co dissociation from the maturase are discussed. PMID:27268267

  8. GPM Video of In-fa

    NASA Video Gallery

    On Nov. 19 GPM saw a few towering storms in In-fa's eye wall were reaching heights of up to 17.3 km (10.7 miles). The most intense precipitation was measured in In-fa's eye wall by DPR where it was...

  9. Nuclear resonance vibrational spectroscopy reveals the FeS cluster composition and active site vibrational properties of an O2-tolerant NAD+-reducing [NiFe] hydrogenase

    DOE PAGES

    Lauterbach, Lars; Wang, Hongxin; Horch, Marius; Gee, Leland B.; Yoda, Yoshitaka; Tanaka, Yoshihito; Zebger, Ingo; Lenz, Oliver; Cramer, Stephen P.

    2014-10-30

    Hydrogenases are complex metalloenzymes that catalyze the reversible splitting of molecular hydrogen into protons and electrons essentially without overpotential. The NAD+-reducing soluble hydrogenase (SH) from Ralstonia eutropha is capable of H2 conversion even in the presence of usually toxic dioxygen. The molecular details of the underlying reactions are largely unknown, mainly because of limited knowledge of the structure and function of the various metal cofactors present in the enzyme. Here, all iron-containing cofactors of the SH were investigated by 57Fe specific nuclear resonance vibrational spectroscopy (NRVS). Our data provide experimental evidence for one [2Fe2S] center and four [4Fe4S] clusters, whichmore » is consistent with the amino acid sequence composition. Only the [2Fe2S] cluster and one of the four [4Fe4S] clusters were reduced upon incubation of the SH with NADH. This finding explains the discrepancy between the large number of FeS clusters and the small amount of FeS cluster-related signals as detected by electron paramagnetic resonance spectroscopic analysis of several NAD+-reducing hydrogenases. For the first time, Fe–CO and Fe–CN modes derived from the [NiFe] active site could be distinguished by NRVS through selective 13C labeling of the CO ligand. This strategy also revealed the molecular coordinates that dominate the individual Fe–CO modes. The present approach explores the complex vibrational signature of the Fe–S clusters and the hydrogenase active site, thereby showing that NRVS represents a powerful tool for the elucidation of complex biocatalysts containing multiple cofactors.« less

  10. The structure of genetically modified iron-sulfur cluster F(x) in photosystem I as determined by X-ray absorption spectroscopy.

    PubMed

    Gong, Xiao-Min; Hochman, Yehoshua; Lev, Tal; Bunker, Grant; Carmeli, Chanoch

    2009-02-01

    Photosystem I (PS I) mediates light-induced electron transfer from P700 through a chlorophyll a, a quinone and a [4Fe-4S] iron-sulfur cluster F(X), located on the core subunits PsaA/B to iron-sulfur clusters F(A/B) on subunit PsaC. Structure function relations in the native and in the mutant (psaB-C565S/D566E) of the cysteine ligand of F(X) cluster were studied by X-ray absorption spectroscopy (EXAFS) and transient spectroscopy. The structure of F(X) was determined in PS I lacking clusters F(A/B) by interruption of the psaC2 gene of PS I in the cyanobacterium Synechocystis sp PCC 6803. PsaC-deficient mutant cells assembled the core subunits of PS I which mediated electron transfer mostly to the phylloquinone. EXAFS analysis of the iron resolved a [4Fe-4S] cluster in the native PsaC-deficient PS I. Each iron had 4 sulfur and 3 iron atoms in the first and second shells with average Fe-S and Fe-Fe distances of 2.27 A and 2.69 A, respectively. In the C565S/D566E serine mutant, one of the irons of the cluster was ligated to three oxygen atoms with Fe-O distance of 1.81 A. The possibility that the structural changes induced an increase in the reorganization energy that consequently decreased the rate of electron transfer from the phylloquinone to F(X) is discussed.

  11. Key players and their role during mitochondrial iron-sulfur cluster biosynthesis.

    PubMed

    Rawat, Swati; Stemmler, Timothy L

    2011-01-17

    Iron-sulfur clusters are multifaceted iron-containing cofactors coordinated and utilized by numerous proteins in nearly all biological systems. Fe-S-cluster-containing proteins help direct pathways essential for cell viability and participate in biological applications ranging from nucleotide biosynthesis and stability, protein translation, enzyme catalysis, and mitochondrial metabolism. Fe-S-containing proteins function by utilizing the unique electronic and chemical properties inherent in the Fe containing cofactor. Fe-S clusters are constructed of inorganic iron and sulfide arranged in a distinct caged structural makeup ranging from [Fe(2) -S(2) ], [Fe(3) -S(4) ], [Fe(4) -S(4) ], up to [Fe(8) -S(8) ] clusters. In eukaryotes, cluster activity is controlled in part at the assembly level and the major pathway for cluster production exists within the mitochondria. Recent insight into the pathway of mitochondrial cluster assembly has come from new in vivo and in vitro reports that provided direct insight into how all protein partners within the assembly pathway interact. However, we are only just beginning to understand the role of each protein within this complex pageant that is mitochondrial Fe-S cluster assembly. In this report we present results, using the yeast model for mitochondrial assembly, to describe the molecular details of how important proteins in the pathway coordinate for cluster assembly. PMID:21226084

  12. The FeMoco-deficient MoFe protein produced by a nifH deletion strain of Azotobacter vinelandii shows unusual P-cluster features.

    PubMed

    Ribbe, Markus W; Hu, Yilin; Guo, Maolin; Schmid, Benedikt; Burgess, Barbara K

    2002-06-28

    The His-tag MoFe protein expressed by the nifH deletion strain Azotobacter vinelandii DJ1165 (Delta(nifH) MoFe protein) was purified in large quantity. The alpha(2)beta(2) tetrameric Delta(nifH) MoFe protein is FeMoco-deficient based on metal analysis and the absence of the S = 3/2 EPR signal, which arises from the FeMo cofactor center in wild-type MoFe protein. The Delta(nifH) MoFe protein contains 18.6 mol Fe/mol and, upon reduction with dithionite, exhibits an unusually strong S = 1/2 EPR signal in the g approximately 2 region. The indigo disulfonate-oxidized Delta(nifH) MoFe protein does not show features of the P(2+) state of the P-cluster of the Delta(nifB) MoFe protein. The oxidized Delta(nifH) MoFe protein is able to form a specific complex with the Fe protein containing the [4Fe-4S](1+) cluster and facilitates the hydrolysis of MgATP within this complex. However, it is not able to accept electrons from the [4Fe-4S](1+) cluster of the Fe protein. Furthermore, the dithionite-reduced Delta(nifH) MoFe can be further reduced by Ti(III) citrate, which is quite unexpected. These unusual catalytic and spectroscopic properties might indicate the presence of a P-cluster precursor or a P-cluster trapped in an unusual conformation or oxidation state. PMID:11978793

  13. GPM Video of In-fa

    NASA Video Gallery

    On Nov. 23, GPM saw In-fa dropping rain at an extreme rate of over 266 mm (10.5 inches) per hour in storms just to the northwest of the typhoon's eye where thunderstorms reached altitudes of over 1...

  14. Spectroscopic investigation of selective cluster conversion of archaeal zinc-containing ferredoxin from Sulfolobus sp. strain 7.

    PubMed

    Iwasaki, T; Watanabe, E; Ohmori, D; Imai, T; Urushiyama, A; Akiyama, M; Hayashi-Iwasaki, Y; Cosper, N J; Scott, R A

    2000-08-18

    Archaeal zinc-containing ferredoxin from Sulfolobus sp. strain 7 contains one [3Fe-4S] cluster (cluster I), one [4Fe-4S] cluster (cluster II), and one isolated zinc center. Oxidative degradation of this ferredoxin led to the formation of a stable intermediate with 1 zinc and approximately 6 iron atoms. The metal centers of this intermediate were analyzed by electron paramagnetic resonance (EPR), low temperature resonance Raman, x-ray absorption, and (1)H NMR spectroscopies. The spectroscopic data suggest that (i) cluster II was selectively converted to a cubane [3Fe-4S](1+) cluster in the intermediate, without forming a stable radical species, and that (ii) the local metric environments of cluster I and the isolated zinc site did not change significantly in the intermediate. It is concluded that the initial step of oxidative degradation of the archaeal zinc-containing ferredoxin is selective conversion of cluster II, generating a novel intermediate containing two [3Fe-4S] clusters and an isolated zinc center. At this stage, significant structural rearrangement of the protein does not occur. We propose a new scheme for oxidative degradation of dicluster ferredoxins in which each cluster converts in a stepwise manner, prior to apoprotein formation, and discuss its structural and evolutionary implications.

  15. Nuclear resonance vibrational spectroscopy reveals the FeS cluster composition and active site vibrational properties of an O2-tolerant NAD+-reducing [NiFe] hydrogenase

    SciTech Connect

    Lauterbach, Lars; Wang, Hongxin; Horch, Marius; Gee, Leland B.; Yoda, Yoshitaka; Tanaka, Yoshihito; Zebger, Ingo; Lenz, Oliver; Cramer, Stephen P.

    2014-10-30

    Hydrogenases are complex metalloenzymes that catalyze the reversible splitting of molecular hydrogen into protons and electrons essentially without overpotential. The NAD+-reducing soluble hydrogenase (SH) from Ralstonia eutropha is capable of H2 conversion even in the presence of usually toxic dioxygen. The molecular details of the underlying reactions are largely unknown, mainly because of limited knowledge of the structure and function of the various metal cofactors present in the enzyme. Here, all iron-containing cofactors of the SH were investigated by 57Fe specific nuclear resonance vibrational spectroscopy (NRVS). Our data provide experimental evidence for one [2Fe2S] center and four [4Fe4S] clusters, which is consistent with the amino acid sequence composition. Only the [2Fe2S] cluster and one of the four [4Fe4S] clusters were reduced upon incubation of the SH with NADH. This finding explains the discrepancy between the large number of FeS clusters and the small amount of FeS cluster-related signals as detected by electron paramagnetic resonance spectroscopic analysis of several NAD+-reducing hydrogenases. For the first time, Fe–CO and Fe–CN modes derived from the [NiFe] active site could be distinguished by NRVS through selective 13C labeling of the CO ligand. This strategy also revealed the molecular coordinates that dominate the individual Fe–CO modes. The present approach explores the complex vibrational signature of the Fe–S clusters and the hydrogenase active site, thereby showing that NRVS represents a powerful tool for the elucidation of complex biocatalysts containing multiple cofactors.

  16. Characterization of iron-sulfur cluster assembly protein IscA from Acidithiobacillus ferrooxidans.

    PubMed

    Qian, Lin; Zheng, Chunli; Liu, Jianshe

    2013-03-01

    IscA is a key member of the iron-sulfur cluster assembly machinery found in bacteria and eukaryotes, but the mechanism of its function in the biogenesis of iron-sulfur cluster remains elusive. In this paper, we demonstrate that Acidithiobacillus ferrooxidans IscA is a [4Fe-4S] cluster binding protein, and it can bind iron in the presence of DTT with an apparent iron association constant of 4·10(20) M(-1). The iron binding in IscA can be promoted by oxygen through oxidizing ferrous iron to ferric iron. Furthermore, we show that the iron bound form of IscA can be converted to iron-sulfur cluster bound form in the presence of IscS and L-cysteine in vitro. Substitution of the invariant cysteine residues Cys35, Cys99, or Cys101 in IscA abolishes the iron binding activity of the protein; the IscA mutants that fail to bind iron are unable to assemble the iron-sulfur clusters. Further studies indicate that the iron-loaded IscA could act as an iron donor for the assembly of iron-sulfur clusters in the scaffold protein IscU in vitro. Taken together, these findings suggest that A. ferrooxidans IscA is not only an iron-sulfur protein, but also an iron binding protein that can act as an iron donor for biogenesis of iron-sulfur clusters. PMID:23586717

  17. Iron-sulfur cluster damage by the superoxide radical in neural tissues of the SOD1(G93A) ALS rat model.

    PubMed

    Popović-Bijelić, Ana; Mojović, Miloš; Stamenković, Stefan; Jovanović, Miloš; Selaković, Vesna; Andjus, Pavle; Bačić, Goran

    2016-07-01

    Extensive clinical investigations, in hand with biochemical and biophysical research, have associated brain iron accumulation with the pathogenesis of the amyotrophic lateral sclerosis (ALS) disease. The origin of iron is still not identified, but it is proposed that it forms redox active complexes that can participate in the Fenton reaction generating the toxic hydroxyl radical. In this paper, the state of iron in the neural tissues isolated from SOD1(G93A) transgenic rats was investigated using low temperature EPR spectroscopy and is compared with that of nontransgenic (NTg) littermates. The results showed that iron in neural tissues is present as high- and low-spin, heme and non-heme iron. It appears that the SOD1(G93A) rat neural tissues were most likely exposed in vivo to higher amounts of reactive oxygen species when compared to the corresponding NTg tissues, as they showed increased oxidized [3Fe-4S](1+) cluster content relative to [4Fe-4S](1+). Also, the activity of cytochrome c oxidase (CcO) was found to be reduced in these tissues, which may be associated with the observed uncoupling of heme a3 Fe and CuB in the O2-reduction site of the enzyme. Furthermore, the SOD1(G93A) rat spinal cords and brainstems contained more manganese, presumably from MnSOD, than those of NTg rats. The addition of potassium superoxide to all neural tissues ex vivo, led to the [4Fe-4S]→[3Fe-4S] cluster conversion and concurrent release of Fe. These results suggest that the superoxide anion may be the cause of the observed oxidative damage to SOD1(G93A) rat neural tissues and that the iron-sulfur clusters may be the source of poorly liganded redox active iron implicated in ALS pathogenesis. Low temperature EPR spectroscopy appears to be a valuable tool in assessing the role of metals in neurodegenerative diseases.

  18. The roles of coenzyme A in the pyruvate:ferredoxin oxidoreductase reaction mechanism: rate enhancement of electron transfer from a radical intermediate to an iron-sulfur cluster.

    PubMed

    Furdui, Cristina; Ragsdale, Stephen W

    2002-08-01

    Pyruvate:ferredoxin oxidoreductase (PFOR) catalyzes the coenzyme A (CoA)-dependent oxidative decarboxylation of pyruvate. In many autotrophic anaerobes, PFOR links the Wood-Ljungdahl pathway to glycolysis and to cell carbon synthesis. Herein, we cloned and sequenced the M. thermoacetica PFOR, demonstrating strong structural homology with the structurally characterized D. africanus PFOR, including the presence of three [4Fe-4S] clusters per monomeric unit. The PFOR reaction includes a hydroxyethyl-thiamin pyrophosphate (HE-TPP) radical intermediate, which forms rapidly after PFOR reacts with pyruvate. This step precedes electron transfer from the HE-TPP radical intermediate to an intramolecular [4Fe-4S] cluster. We show that CoA increases the rate of this redox reaction by 10(5)-fold. Analysis by Marcus theory indicates that, in the absence of CoA, this is a true electron-transfer reaction; however, in its presence, electron transfer is gated by an adiabatic event. Analysis by the Eyring equation indicates that entropic effects dominate this rate enhancement. Our results indicate that the energy of binding CoA contributes minimally to the rate increase since the thiol group of CoA lends over 40 kJ/mol to the reaction, whereas components of CoA that afford most of the cofactor's binding energy contribute minimally. Major conformational changes also do not appear to explain the rate enhancement. We propose several ways that CoA can accomplish this rate increase, including formation of a highly reducing adduct with the HE-TPP radical to increase the driving force for electron transfer. We also consider the possibility that CoA itself forms part of the electron-transfer pathway. PMID:12146957

  19. [FeFe]-hydrogenase oxygen inactivation is initiated at the H cluster 2Fe subcluster.

    PubMed

    Swanson, Kevin D; Ratzloff, Michael W; Mulder, David W; Artz, Jacob H; Ghose, Shourjo; Hoffman, Andrew; White, Spencer; Zadvornyy, Oleg A; Broderick, Joan B; Bothner, Brian; King, Paul W; Peters, John W

    2015-02-11

    The [FeFe]-hydrogenase catalytic site H cluster is a complex iron sulfur cofactor that is sensitive to oxygen (O2). The O2 sensitivity is a significant barrier for production of hydrogen as an energy source in water-splitting, oxygenic systems. Oxygen reacts directly with the H cluster, which results in rapid enzyme inactivation and eventual degradation. To investigate the progression of O2-dependent [FeFe]-hydrogenase inactivation and the process of H cluster degradation, the highly O2-sensitive [FeFe]-hydrogenase HydA1 from the green algae Chlamydomonas reinhardtii was exposed to defined concentrations of O2 while monitoring the loss of activity and accompanying changes in H cluster spectroscopic properties. The results indicate that H cluster degradation proceeds through a series of reactions, the extent of which depend on the initial enzyme reduction/oxidation state. The degradation process begins with O2 interacting and reacting with the 2Fe subcluster, leading to degradation of the 2Fe subcluster and leaving an inactive [4Fe-4S] subcluster state. This final inactive degradation product could be reactivated in vitro by incubation with 2Fe subcluster maturation machinery, specifically HydF(EG), which was observed by recovery of enzyme activity.

  20. [FeFe]-hydrogenase oxygen inactivation is initiated at the H cluster 2Fe subcluster.

    PubMed

    Swanson, Kevin D; Ratzloff, Michael W; Mulder, David W; Artz, Jacob H; Ghose, Shourjo; Hoffman, Andrew; White, Spencer; Zadvornyy, Oleg A; Broderick, Joan B; Bothner, Brian; King, Paul W; Peters, John W

    2015-02-11

    The [FeFe]-hydrogenase catalytic site H cluster is a complex iron sulfur cofactor that is sensitive to oxygen (O2). The O2 sensitivity is a significant barrier for production of hydrogen as an energy source in water-splitting, oxygenic systems. Oxygen reacts directly with the H cluster, which results in rapid enzyme inactivation and eventual degradation. To investigate the progression of O2-dependent [FeFe]-hydrogenase inactivation and the process of H cluster degradation, the highly O2-sensitive [FeFe]-hydrogenase HydA1 from the green algae Chlamydomonas reinhardtii was exposed to defined concentrations of O2 while monitoring the loss of activity and accompanying changes in H cluster spectroscopic properties. The results indicate that H cluster degradation proceeds through a series of reactions, the extent of which depend on the initial enzyme reduction/oxidation state. The degradation process begins with O2 interacting and reacting with the 2Fe subcluster, leading to degradation of the 2Fe subcluster and leaving an inactive [4Fe-4S] subcluster state. This final inactive degradation product could be reactivated in vitro by incubation with 2Fe subcluster maturation machinery, specifically HydF(EG), which was observed by recovery of enzyme activity. PMID:25579778

  1. Identification and function of auxiliary iron-sulfur clusters in radical SAM enzymes.

    PubMed

    Lanz, Nicholas D; Booker, Squire J

    2012-11-01

    Radical SAM (RS) enzymes use a 5'-deoxyadenosyl 5'-radical generated from a reductive cleavage of S-adenosyl-l-methionine to catalyze over 40 distinct reaction types. A distinguishing feature of these enzymes is a [4Fe-4S] cluster to which each of three iron ions is ligated by three cysteinyl residues most often located in a Cx(3)Cx(2)C motif. The α-amino and α-carboxylate groups of SAM anchor the molecule to the remaining iron ion, which presumably facilitates its reductive cleavage. A subset of RS enzymes contains additional iron-sulfur clusters, - which we term auxiliary clusters - most of which have unidentified functions. Enzymes in this subset are involved in cofactor biosynthesis and maturation, post-transcriptional and post-translational modification, enzyme activation, and antibiotic biosynthesis. The additional clusters in these enzymes have been proposed to function in sulfur donation, electron transfer, and substrate anchoring. This review will highlight evidence supporting the presence of multiple iron-sulfur clusters in these enzymes as well as their predicted roles in catalysis. This article is part of a special issue entitled: Radical SAM enzymes and radical enzymology.

  2. MAN or FA from n-butane

    SciTech Connect

    Di Cio, A.; Verde, L.

    1985-08-01

    Unsaturated polyester resins were first produced mostly from fumaric acid (FA) rather than from maleic anhydride (MAN). This is perfectly understandable if we consider that, using fumaric acid as raw material, polycondensates with a more homogeneous (less branched) structure are obtained, thus producing resins characterized by a more uniform and reproducible chemical and mechanical properties. Presently, for economical reasons, fumaric acid is used marginally as a MAN substitute in the production of polyester resins. These resins account for a major share (50%) of the overall MAN consumption in the U.S. and in Western Europe.

  3. Excessive Food Intake, Obesity and Inflammation Process in Zucker fa/fa Rat Pancreatic Islets

    PubMed Central

    Chentouf, Myriam; Dubois, Gregor; Jahannaut, Céline; Castex, Françoise; Lajoix, Anne Dominique; Gross, René; Peraldi-Roux, Sylvie

    2011-01-01

    Inappropriate food intake-related obesity and more importantly, visceral adiposity, are major risk factors for the onset of type 2 diabetes. Evidence is emerging that nutriment-induced β-cell dysfunction could be related to indirect induction of a state of low grade inflammation. Our aim was to study whether hyperphagia associated obesity could promote an inflammatory response in pancreatic islets leading to ß-cell dysfunction. In the hyperphagic obese insulin resistant male Zucker rat, we measured the level of circulating pro-inflammatory cytokines and estimated their production as well as the expression of their receptors in pancreatic tissue and β-cells. Our main findings concern intra-islet pro-inflammatory cytokines from fa/fa rats: IL-1β, IL-6 and TNFα expressions were increased; IL-1R1 was also over-expressed with a cellular redistribution also observed for IL-6R. To get insight into the mechanisms involved in phenotypic alterations, abArrays were used to determine the expression profile of proteins implicated in different membrane receptors signaling, apoptosis and cell cycle pathways. Despite JNK overexpression, cell viability was unaffected probably because of decreases in cleaved caspase3 as well as in SMAC/DIABLO and APP, involved in the induction and amplification of apoptosis. Concerning β-cell proliferation, decreases in important cell cycle regulators (Cyclin D1, p35) and increased expression of SMAD4 probably contribute to counteract and restrain hyperplasia in fa/fa rat islets. Finally and probably as a result of IL-1β and IL-1R1 increased expressions with sub-cellular redistribution of the receptor, islets from fa/fa rats were found more sensitive to both stimulating and inhibitory concentrations of the cytokine; this confers some physiopathological relevance to a possible autocrine regulation of β-cell function by IL-1β. These results support the hypothesis that pancreatic islets from prediabetic fa/fa rats undergo an inflammatory

  4. Unanticipated coordination of tris buffer to the Radical SAM cluster of the RimO methylthiotransferase.

    PubMed

    Molle, Thibaut; Clémancey, Martin; Latour, Jean-Marc; Kathirvelu, Velavan; Sicoli, Giuseppe; Forouhar, Farhad; Mulliez, Etienne; Gambarelli, Serge; Atta, Mohamed

    2016-07-01

    Radical SAM enzymes generally contain a [4Fe-4S](2+/1+) (RS cluster) cluster bound to the protein via the three cysteines of a canonical motif CxxxCxxC. The non-cysteinyl iron is used to coordinate SAM via its amino-carboxylate moiety. The coordination-induced proximity between the cluster acting as an electron donor and the adenosyl-sulfonium bond of SAM allows for the homolytic cleavage of the latter leading to the formation of the reactive 5'-deoxyadenosyl radical used for substrate activation. Most of the structures of Radical SAM enzymes have been obtained in the presence of SAM, and therefore, little is known about the situation when SAM is not present. In this report, we show that RimO, a methylthiotransferase belonging to the radical SAM superfamily, binds a Tris molecule in the absence of SAM leading to specific spectroscopic signatures both in Mössbauer and pulsed EPR spectroscopies. These data provide a cautionary note for researchers who work with coordinative unsaturated iron sulfur clusters. PMID:27259294

  5. Low-energy spectrum of iron-sulfur clusters directly from many-particle quantum mechanics

    NASA Astrophysics Data System (ADS)

    Sharma, Sandeep; Sivalingam, Kantharuban; Neese, Frank; Chan, Garnet Kin-Lic

    2014-10-01

    Iron-sulfur clusters are a universal biological motif. They carry out electron transfer, redox chemistry and even oxygen sensing, in diverse processes including nitrogen fixation, respiration and photosynthesis. Their low-lying electronic states are key to their remarkable reactivity, but they cannot be directly observed. Here, we present the first ever quantum calculation of the electronic levels of [2Fe-2S] and [4Fe-4S] clusters free from any model assumptions. Our results highlight the limitations of long-standing models of their electronic structure. In particular, we demonstrate that the widely used Heisenberg double exchange model underestimates the number of states by one to two orders of magnitude, which can conclusively be traced to the absence of Fe dd excitations, thought to be important in these clusters. Furthermore, the electronic energy levels of even the same spin are dense on the scale of vibrational fluctuations and this provides a natural explanation for the ubiquity of these clusters in catalysis in nature.

  6. Fluorescent probes for tracking the transfer of iron-sulfur cluster and other metal cofactors in biosynthetic reaction pathways.

    PubMed

    Vranish, James N; Russell, William K; Yu, Lusa E; Cox, Rachael M; Russell, David H; Barondeau, David P

    2015-01-14

    Iron-sulfur (Fe-S) clusters are protein cofactors that are constructed and delivered to target proteins by elaborate biosynthetic machinery. Mechanistic insights into these processes have been limited by the lack of sensitive probes for tracking Fe-S cluster synthesis and transfer reactions. Here we present fusion protein- and intein-based fluorescent labeling strategies that can probe Fe-S cluster binding. The fluorescence is sensitive to different cluster types ([2Fe-2S] and [4Fe-4S] clusters), ligand environments ([2Fe-2S] clusters on Rieske, ferredoxin (Fdx), and glutaredoxin), and cluster oxidation states. The power of this approach is highlighted with an extreme example in which the kinetics of Fe-S cluster transfer reactions are monitored between two Fdx molecules that have identical Fe-S spectroscopic properties. This exchange reaction between labeled and unlabeled Fdx is catalyzed by dithiothreitol (DTT), a result that was confirmed by mass spectrometry. DTT likely functions in a ligand substitution reaction that generates a [2Fe-2S]-DTT species, which can transfer the cluster to either labeled or unlabeled Fdx. The ability to monitor this challenging cluster exchange reaction indicates that real-time Fe-S cluster incorporation can be tracked for a specific labeled protein in multicomponent assays that include several unlabeled Fe-S binding proteins or other chromophores. Such advanced kinetic experiments are required to untangle the intricate networks of transfer pathways and the factors affecting flux through branch points. High sensitivity and suitability with high-throughput methodology are additional benefits of this approach. We anticipate that this cluster detection methodology will transform the study of Fe-S cluster pathways and potentially other metal cofactor biosynthetic pathways.

  7. Synthesis of the H-Cluster Framework of Iron-Only Hydrogenase

    SciTech Connect

    Tard, Cedric; Liu, Xiaohong; Ibrahim, S K.; Mauizio, Bruschi; De Gioia, Luca; Davies, Sian; Yang, Xin; Wang, Lai S.; Sawers, G; Pickett, Chris J.

    2005-02-10

    The reversible reduction of protons to dihydrogen is deceptively the simplest of reactions but one which requires multi-step catalysis to proceed at practical rates. How the metal-sulfur of the hydrogenases catalyse this interconversion has been the subject has been the subject of intensive structural, spectroscopic and mechanistic studies of the enzymes, of synthetic assemblies and of in silico models. Beyond the intrinsic desire to understand how metallo-sulfur clusters in biology catalyses a range of difficult chemistry, including nitrogen fixation, research on hydrogenase chemistry is particularly driven by the view that understanding active-site structure and function will inform the design of new materials for hydrogen production or uptake, pertinent to energy transduction technology and a hydrogen economy. Herein we report the assembly of the first materials with di-iron sub-sites linked by a thiolate bridge to a (4Fe4S) ? cluster, as found at the active site of the iron-only hydrogenase, the H-cluster.

  8. Iron-sulfur stoichiometry and structure of iron-sulfur clusters in three iron proteins: Evidence for (3Fe-4S) clusters

    SciTech Connect

    Beinert, H.; Emptage, M.H.; Dreyer, J.L.; Scott, R.A.; Hahn, J.E.; Hodgson, K.O.; Thomson, A.J.

    1983-01-01

    Beef heart aconitase contains 3Fe clusters in its inactive and 4Fe clusters in its active form. The fully active form can be restored from the inactive one by insertion of Fe/sup 2 +/, whereas S/sup 2 -/ is not required. Chemical analyses for iron and labile sulfide yield Fe/S/sup 2 -/ ratios of 0.66-0.74 for the inactive and 0.90-1.03 for the active form. Sulfane sulfur (S/sup 0/) was not detected. The authors propose on the basis of these data that the inactive form may arise from the active one by loss of one iron only per cluster with the sulfur remaining as S/sup 2 -/ in a (3Fe-4S) structure. Measurements by extended x-ray absorption fine structure (EXAFS) spectroscopy on the 3Fe form of aconitase yield a Fe..S distance of 2.24 angstrom and a Fe..Fe distance of 2.71 angstrom. This Fe..Fe distance is in agreement with that obtained by EXAFS on ferredoxin II of Desulfovibrio gigas, another 3Fe protein, but disagrees with Fe..Fe distances observed for the 3Fe cluster of Azotobacter vinelandii ferredoxin I by x-ray diffraction--namely, 4.1 angstrom. The authors suggest that this difference may be due to the presence of a (3Fe-3S) structure in the Azotobacter ferredoxin I crystals vs. a (3Fe-4S) structure in liquid or frozen solutions of aconitase. The (3Fe-3S) cluster has been shown to have a relatively flat twist-boat structure, whereas a (3Fe-4S) cluster could be expected to essentially maintain the compact structure of the (4Fe-4S) cluster. This would explain the differences in Fe..Fe distances. Two possible structural models for a (3Fe-4S) cluster are discussed.

  9. Time to Detection with BacT/Alert FA Plus Compared to BacT/Alert FA Blood Culture Media.

    PubMed

    Nutman, A; Fisher Even-Tsur, S; Shapiro, G; Braun, T; Schwartz, D; Carmeli, Y

    2016-09-01

    Rapid identification of the causative pathogen in patients with bacteremia allows adjustment of antibiotic therapy and improves patient outcomes. We compared in vitro and real-life time to detection (TTD) of two blood culture media, BacT/Alert FA (FA) and BacT/Alert FA Plus (FA Plus), for the nine most common species of bacterial pathogens recovered from blood samples. Experimental data from simulated cultures was compared with microbiology records of TTD for both culture media with growth of the species of interest in clinical blood cultures. In the experimental conditions, median TTD was 3.8 hours (23.9 %) shorter using FA Plus media. The magnitude of reduction differed between species. Similarly, in real life data, FA Plus had shorter TTD than FA media; however, the difference between culture media was smaller, and median TTD was only 1 hour (8.5 %) less. We found shorter TTD with BacT/Alert FA Plus culture media, both experimentally and in real-life conditions and unrelated to antibiotic neutralization, highlighting the importance of appropriate blood culture media selection. PMID:27272123

  10. Mass spectrometry of the lithium adducts of diacylglycerols containing hydroxy FA in castor oil and two normal FA

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Castor oil can be used in industry. The molecular species of triacylglycerols containing hydroxy fatty acids (FA) in castor oil have been identified. We report here the identification of twelve diacylglycerols (DAG) containing hydroxy FA in castor oil using positive ion electrospray ionization mass ...

  11. The Nitrogenase FeMo-Cofactor Precursor Formed by NifB Protein: A Diamagnetic Cluster Containing Eight Iron Atoms.

    PubMed

    Guo, Yisong; Echavarri-Erasun, Carlos; Demuez, Marie; Jiménez-Vicente, Emilio; Bominaar, Emile L; Rubio, Luis M

    2016-10-01

    The biological activation of N2 occurs at the FeMo-cofactor, a 7Fe-9S-Mo-C-homocitrate cluster. FeMo-cofactor formation involves assembly of a Fe6-8 -SX -C core precursor, NifB-co, which occurs on the NifB protein. Characterization of NifB-co in NifB is complicated by the dynamic nature of the assembly process and the presence of a permanent [4Fe-4S] cluster associated with the radical SAM chemistry for generating the central carbide. We have used the physiological carrier protein, NifX, which has been proposed to bind NifB-co and deliver it to the NifEN protein, upon which FeMo-cofactor assembly is ultimately completed. Preparation of NifX in a fully NifB-co-loaded form provided an opportunity for Mössbauer analysis of NifB-co. The results indicate that NifB-co is a diamagnetic (S=0) 8-Fe cluster, containing two spectroscopically distinct Fe sites that appear in a 3:1 ratio. DFT analysis of the (57) Fe electric hyperfine interactions deduced from the Mössbauer analysis suggests that NifB-co is either a 4Fe(2+) -4Fe(3+) or 6Fe(2+) -2Fe(3+) cluster having valence-delocalized states.

  12. Epigenetics and development of food allergy (FA) in early childhood.

    PubMed

    Hong, Xiumei; Wang, Xiaobin

    2014-09-01

    This review aims to highlight the latest advance on epigenetics in the development of food allergy (FA) and to offer future perspectives. FA, a condition caused by an immunoglobulin (Ig) E-mediated hypersensitivity reaction to food, has emerged as a major clinical and public health problem worldwide in light of its increasing prevalence, potential fatality, and significant medical and economic impact. Current evidence supports that epigenetic mechanisms are involved in immune regulation and that the epigenome may represent a key "missing piece" of the etiological puzzle for FA. There are a growing number of population-based epigenetic studies on allergy-related phenotypes, mostly focused on DNA methylation. Previous studies mostly applied candidate-gene approaches and have demonstrated that epigenetic marks are associated with multiple allergic diseases and/or with early-life exposures relevant to allergy development (such as early-life smoking exposure, air pollution, farming environment, and dietary fat). Rapid technological advancements have made unbiased genome-wide DNA methylation studies highly feasible, although there are substantial challenge in study design, data analyses, and interpretation of findings. In conclusion, epigenetics represents both an important knowledge gap and a promising research area for FA. Due to the early onset of FA, epigenetic studies of FA in prospective birth cohorts have the potential to better understand gene-environment interactions and underlying biological mechanisms in FA during critical developmental windows (preconception, in utero, and early childhood) and may lead to new paradigms in the diagnosis, prevention, and management of FA and provide novel targets for future drug discovery and therapies for FA. PMID:25096861

  13. NASA Researches the 'FaINT' Side of Sonic Booms

    NASA Video Gallery

    As the latest in a continuing progression of NASA supersonics research projects aimed at reducing or mitigating the effect of sonic booms, the Farfield Investigation of No Boom Threshold, or FaINT,...

  14. F/A-18 FAST Offers Advanced System Test Capability

    NASA Video Gallery

    NASA's Dryden Flight Research Center has modified an F/A-18A Hornet aircraft with additional research flight control computer systems for use as a Full-scale Advanced Systems Test Bed. Previously f...

  15. F/A-18 Automated Aerial Refueling (AAR) Phase 1

    NASA Video Gallery

    Engineers at NASA's Dryden Flight Research Center are evaluating the capability of an F/A-18A aircraft as an in-flight refueling tanker to develop analytical models for an automated aerial refuelin...

  16. Heterozygous FA2H mutations in autism spectrum disorders

    PubMed Central

    2013-01-01

    Background Widespread abnormalities in white matter development are frequently reported in cases of autism spectrum disorders (ASD) and could be involved in the disconnectivity suggested in these disorders. Homozygous mutations in the gene coding for fatty-acid 2-hydroxylase (FA2H), an enzyme involved in myelin synthesis, are associated with complex leukodystrophies, but little is known about the functional impact of heterozygous FA2H mutations. We hypothesized that rare deleterious heterozygous mutations of FA2H might constitute risk factors for ASD. Methods We searched deleterious mutations affecting FA2H, by genotyping 1256 independent patients with ASD genotyped using Genome Wide SNP arrays, and also by sequencing in independent set of 186 subjects with ASD and 353 controls. We then explored the impact of the identified mutations by measuring FA2H enzymatic activity and expression, in transfected COS7 cells. Results One heterozygous deletion within 16q22.3-q23.1 including FA2H was observed in two siblings who share symptoms of autism and severe cognitive impairment, axial T2-FLAIR weighted MRI posterior periventricular white matter lesions. Also, two rare non-synonymous mutations (R113W and R113Q) were reported. Although predictive models suggested that R113W should be a deleterious, we did not find that FA2H activity was affected by expression of the R113W mutation in cultured COS cells. Conclusions While our results do not support a major role for FA2H coding variants in ASD, a screening of other genes related to myelin synthesis would allow us to better understand the role of non-neuronal elements in ASD susceptibility. PMID:24299421

  17. Importance of Hydrogen Bonding in Fine Tuning the [2Fe-2S] Cluster Redox Potential of HydC from Thermotoga maritima.

    PubMed

    Birrell, James A; Laurich, Christoph; Reijerse, Edward J; Ogata, Hideaki; Lubitz, Wolfgang

    2016-08-01

    Iron-sulfur clusters form one of the largest and most diverse classes of enzyme cofactors in nature. They may serve as structural factors, form electron transfer chains between active sites and external redox partners, or form components of enzyme active sites. Their specific role is a consequence of the cluster type and the surrounding protein environment. The relative effects of these factors are not completely understood, and it is not yet possible to predict the properties of iron-sulfur clusters based on amino acid sequences or rationally tune their properties to generate proteins with new desirable functions. Here, we generate mutations in a [2Fe-2S] cluster protein, the TmHydC subunit of the trimeric [FeFe]-hydrogenase from Thermotoga maritima, to study the factors that affect its redox potential. Saturation mutagenesis of Val131 was used to tune the redox potential over a 135 mV range and revealed that cluster redox potential and electronic properties correlate with amino acid hydrophobicity and the ability to form hydrogen bonds to the cluster. Proline scanning mutagenesis between pairs of ligating cysteines was used to remove backbone amide hydrogen bonds to the cluster and decrease the redox potential by up to 132 mV, without large structural changes in most cases. However, substitution of Gly83 with proline caused a change of HydC to a [4Fe-4S] cluster protein with a redox potential of -526 mV. Together, these results confirm the importance of hydrogen bonding in tuning cluster redox potentials and demonstrate the versatility of iron-sulfur cluster protein folds at binding different types of clusters. PMID:27396836

  18. FaPYR1 is involved in strawberry fruit ripening.

    PubMed

    Chai, Ye-Mao; Jia, Hai-Feng; Li, Chun-Li; Dong, Qing-Hua; Shen, Yuan-Yue

    2011-10-01

    Although the plant hormone abscisic acid (ABA) has been suggested to play a role in the ripening of non-climatic fruit, direct genetic/molecular evidence is lacking. In the present study, a strawberry gene homologous to the Arabidopsis ABA receptor gene PYR1, named FaPYR1, was isolated and characterized. The 627 bp cDNA includes an intact open reading frame that encodes a deduced protein of 208 amino acids, in which putative conserved domains were detected by homology analysis. Using tobacco rattle virus-induced gene silencing (VIGS), the FaPYR1 gene was silenced in strawberry fruit. Down-regulation of the FaPYR1 gene not only significantly delayed fruit ripening, but also markedly altered ABA content, ABA sensitivity, and a set of ABA-responsive gene transcripts, including ABI1 and SnRK2. Furthermore, the loss of red colouring in FaPYR1 RNAi (RNA interference) fruits could not be rescued by exogenously applied ABA, which could promote the ripening of wild-type fruits. Collectively, these results demonstrate that the putative ABA receptor FaPYR1 acts as a positive regulator in strawberry fruit ripening. It was also revealed that the application of the VIGS technique in strawberry fruit could be used as a novel tool for studying strawberry fruit development.

  19. Dark-operative protochlorophyllide oxidoreductase generates substrate radicals by an iron-sulphur cluster in bacteriochlorophyll biosynthesis

    PubMed Central

    Nomata, Jiro; Kondo, Toru; Mizoguchi, Tadashi; Tamiaki, Hitoshi; Itoh, Shigeru; Fujita, Yuichi

    2014-01-01

    Photosynthesis converts solar energy to chemical energy using chlorophylls (Chls). In a late stage of biosynthesis of Chls, dark-operative protochlorophyllide (Pchlide) oxidoreductase (DPOR), a nitrogenase-like enzyme, reduces the C17 = C18 double bond of Pchlide and drastically changes the spectral properties suitable for photosynthesis forming the parental chlorin ring for Chl a. We previously proposed that the spatial arrangement of the proton donors determines the stereospecificity of the Pchlide reduction based on the recently resolved structure of the DPOR catalytic component, NB-protein. However, it was not clear how the two-electron and two-proton transfer events are coordinated in the reaction. In this study, we demonstrate that DPOR initiates a single electron transfer reaction from a [4Fe-4S]-cluster (NB-cluster) to Pchlide, generating Pchlide anion radicals followed by a single proton transfer, and then, further electron/proton transfer steps transform the anion radicals into chlorophyllide (Chlide). Thus, DPOR is a unique iron-sulphur enzyme to form substrate radicals followed by sequential proton- and electron-transfer steps with the protein folding very similar to that of nitrogenase. This novel radical-mediated reaction supports the biosynthesis of Chl in a wide variety of photosynthetic organisms. PMID:24965831

  20. Dihydroxy acid dehydratase from spinach contains a [2Fe-2S] cluster.

    PubMed

    Flint, D H; Emptage, M H

    1988-03-15

    Dihydroxy acid dehydratase, the third enzyme in the branched-chain amino acid biosynthetic pathway, has been purified to homogeneity (5000-fold) from spinach leaves. The molecular weights of dihydroxy acid dehydratase as determined by sodium dodecyl sulfate and native gel electrophoresis are 63,000 and 110,000, respectively, suggesting the native enzyme is a dimer. 2 moles of iron were found per mol of protein monomer. Chemical analyses of iron and labile sulfide gave an Fe/S2- ratio of 0.95. The EPR spectrum of dithionite-reduced enzyme (gavg = 1.91) is similar to spectra characteristic of Rieske Fe-S proteins and has a spin concentration of 1 spin/1.9 irons. These results strongly suggest that dihydroxy acid dehydratase contains a [2Fe-2S] cluster, a novel finding for enzymes of the hydrolyase class. In contrast to the Rieske Fe-S proteins, the redox potential of the Fe-S cluster is quite low (-470 mV). Upon addition of substrate, the EPR signal of the reduced enzyme changes to one typical of 2Fe ferredoxins (gavg = 1.95), and the visible absorption spectrum of the native enzyme shows substantial changes between 400 and 600 nm. Reduction of the Fe-S cluster decreases the enzyme activity by 6-fold under Vmax conditions. These results suggest the direct involvement of the [2Fe-2S] cluster of dihydroxy acid dehydratase in catalysis. Similar conclusions have been reached for the catalytic involvement of the [4Fe-4S] cluster of the hydrolyase aconitase (Emptage, M. H., Kent, T. A., Kennedy, M. C., Beinert, H., and Münck, E. (1983) Proc. Natl. Acad. Sci. U. S. A. 80, 4674-4678).

  1. Spectroscopic classification of ASASSN-14ew and ASASSN-14fa

    NASA Astrophysics Data System (ADS)

    Takats, K.; Bufano, F.; Pignata, G.; Prieto, J. L.

    2014-08-01

    We report the spectroscopic classification of ASASSN-14ew (ATel #6367) and ASASSN-14fa (ATel #6372). The optical spectra (range 450-880 nm) were obtained on August 11.2 and 11.3 UT, respectively, with the SOAR telescope (+ Goodman Spectrograph).

  2. "What D'ya Mean, Project SOL-FA?"

    ERIC Educational Resources Information Center

    Hardman, Olga S.

    1981-01-01

    Since 1977, Project Sol-fa, funded with an ESEA Title IV-C grant has provided Harrison County primary teachers with inservice training in the Kodaly method of music education. This article provides information on program funding, costs, and accomplishments. Evaluation forms and the inservice syllabus are appended. (SJL)

  3. Birth order and male androphilia in Samoan fa'afafine

    PubMed Central

    Vasey, Paul L; VanderLaan, Doug P

    2007-01-01

    The manner in which male androphilia is publicly expressed varies cross-culturally. As such, it is unclear whether distinct or common underlying causal processes characterize male androphilia in different cultures. Establishing the existence of cross-cultural universals in male androphilia is one means of ascertaining whether common biological bases underlie this phenomenon despite its culturally distinct forms. The evidence that the number of older biological brothers increases the odds of androphilia in later-born males has been well documented for Western samples (i.e. the fraternal birth order effect); but there is little evidence for this effect in non-Western samples. Here, we compare the birth order of androphilic males (i.e. fa'afafine) and gynephilic males from the politically autonomous Polynesian nation of Independent Samoa. Results indicate that relative to gynephilic males, fa'afafine tend to have more siblings and are generally later born when birth order is quantified using Slater, fraternal and sororal indices. More specifically, fa'afafine tend to have a greater number of older brothers, older sisters and younger brothers. We discuss the observed effects in relation to the differing reproductive patterns exhibited by the mothers of fa'afafine and gynephilic males, and to existing social and biological theories for sexual orientation. PMID:17412683

  4. IRAC F/A-18 RFCS on NASA 853

    NASA Technical Reports Server (NTRS)

    Pahli, Joseph

    2009-01-01

    F/A-18 testbed development and flight research are highlighted in this presentation. The current focus is on stability, specifically adaptive flight control, but soon the focus will move towards stability and maneuverability, examining flight planning and guidance, adaptive flight control, engine control and airframe and structures. Later research will additionally review V and V methods. Current and future IRAC plans are highlighted.

  5. Hemerythrins in the microaerophilic bacterium Campylobacter jejuni help protect key iron–sulphur cluster enzymes from oxidative damage

    PubMed Central

    Kendall, John J; Barrero-Tobon, Angelica M; Hendrixson, David R; Kelly, David J

    2014-01-01

    Microaerophilic bacteria are adapted to low oxygen environments, but the mechanisms by which their growth in air is inhibited are not well understood. The citric acid cycle in the microaerophilic pathogen Campylobacter jejuni is potentially vulnerable, as it employs pyruvate and 2-oxoglutarate:acceptor oxidoreductases (Por and Oor), which contain labile (4Fe-4S) centres. Here, we show that both enzymes are rapidly inactivated after exposure of cells to a fully aerobic environment. We investigated the mechanisms that might protect enzyme activity and identify a role for the hemerythrin HerA (Cj0241). A herA mutant exhibits an aerobic growth defect and reduced Por and Oor activities after exposure to 21% (v/v) oxygen. Slow anaerobic recovery of these activities after oxygen damage was observed, but at similar rates in both wild-type and herA strains, suggesting the role of HerA is to prevent Fe-S cluster damage, rather than promote repair. Another hemerythrin (HerB; Cj1224) also plays a protective role. Purified HerA and HerB exhibited optical absorption, ligand binding and resonance Raman spectra typical of μ-oxo-bridged di-iron containing hemerythrins. We conclude that oxygen lability and poor repair of Por and Oor are major contributors to microaerophily in C. jejuni; hemerythrins help prevent enzyme damage microaerobically or during oxygen transients. PMID:24245612

  6. A thermostable hybrid cluster protein from Pyrococcus furiosus: effects of the loss of a three helix bundle subdomain.

    PubMed

    Overeijnder, Marieke L; Hagen, Wilfred R; Hagedoorn, Peter-Leon

    2009-06-01

    Pyrococcus furiosus hybrid cluster protein (HCP) was expressed in Escherichia coli, purified, and characterized. This is the first archaeal and thermostable HCP to be isolated. Compared with the protein sequences of previously characterized HCPs from mesophiles, the protein sequence of P. furiosus HCP exhibits a deletion of approximately 13 kDa as a single amino acid stretch just after the N-terminal cysteine motif, characteristic for class-III HCPs from (hyper)thermophilic archaea and bacteria. The protein was expressed as a thermostable, soluble homodimeric protein. Hydroxylamine reductase activity of P. furiosus HCP showed a K(m) value of 0.40 mM and a k(cat) value of 3.8 s(-1) at 70 degrees C and pH 9.0. Electron paramagnetic resonance spectroscopy showed evidence for the presence of a spin-admixed, S = 3/2 [4Fe-4S](+) cubane cluster and of the hybrid cluster. The cubane cluster of P. furiosus HCP is presumably coordinated by a CXXC-X(7)-C-X(5)-C motif close to the N-terminus, which is similar to the CXXC-X(8)-C-X(5)-C motif of the Desulfovibrio desulfuricans and Desulfovibrio vulgaris HCPs. Amino acid sequence alignment and homology modeling of P. furiosus HCP reveal that the deletion results in a loss of one of the two three-helix bundles of domain 1. Clearly the loss of one of the three-helix bundles of domain 1 does not diminish the hydroxylamine reduction activity and the incorporation of the iron-sulfur clusters. PMID:19241093

  7. A thermostable hybrid cluster protein from Pyrococcus furiosus: effects of the loss of a three helix bundle subdomain.

    PubMed

    Overeijnder, Marieke L; Hagen, Wilfred R; Hagedoorn, Peter-Leon

    2009-06-01

    Pyrococcus furiosus hybrid cluster protein (HCP) was expressed in Escherichia coli, purified, and characterized. This is the first archaeal and thermostable HCP to be isolated. Compared with the protein sequences of previously characterized HCPs from mesophiles, the protein sequence of P. furiosus HCP exhibits a deletion of approximately 13 kDa as a single amino acid stretch just after the N-terminal cysteine motif, characteristic for class-III HCPs from (hyper)thermophilic archaea and bacteria. The protein was expressed as a thermostable, soluble homodimeric protein. Hydroxylamine reductase activity of P. furiosus HCP showed a K(m) value of 0.40 mM and a k(cat) value of 3.8 s(-1) at 70 degrees C and pH 9.0. Electron paramagnetic resonance spectroscopy showed evidence for the presence of a spin-admixed, S = 3/2 [4Fe-4S](+) cubane cluster and of the hybrid cluster. The cubane cluster of P. furiosus HCP is presumably coordinated by a CXXC-X(7)-C-X(5)-C motif close to the N-terminus, which is similar to the CXXC-X(8)-C-X(5)-C motif of the Desulfovibrio desulfuricans and Desulfovibrio vulgaris HCPs. Amino acid sequence alignment and homology modeling of P. furiosus HCP reveal that the deletion results in a loss of one of the two three-helix bundles of domain 1. Clearly the loss of one of the three-helix bundles of domain 1 does not diminish the hydroxylamine reduction activity and the incorporation of the iron-sulfur clusters.

  8. Structural basis for a [4Fe-3S] cluster in the oxygen-tolerant membrane-bound [NiFe]-hydrogenase.

    PubMed

    Shomura, Yasuhito; Yoon, Ki-Seok; Nishihara, Hirofumi; Higuchi, Yoshiki

    2011-11-10

    Membrane-bound respiratory [NiFe]-hydrogenase (MBH), a H(2)-uptake enzyme found in the periplasmic space of bacteria, catalyses the oxidation of dihydrogen: H(2) → 2H(+) + 2e(-) (ref. 1). In contrast to the well-studied O(2)-sensitive [NiFe]-hydrogenases (referred to as the standard enzymes), MBH has an O(2)-tolerant H(2) oxidation activity; however, the mechanism of O(2) tolerance is unclear. Here we report the crystal structures of Hydrogenovibrio marinus MBH in three different redox conditions at resolutions between 1.18 and 1.32 Å. We find that the proximal iron-sulphur (Fe-S) cluster of MBH has a [4Fe-3S] structure coordinated by six cysteine residues--in contrast to the [4Fe-4S] cubane structure coordinated by four cysteine residues found in the proximal Fe-S cluster of the standard enzymes--and that an amide nitrogen of the polypeptide backbone is deprotonated and additionally coordinates the cluster when chemically oxidized, thus stabilizing the superoxidized state of the cluster. The structure of MBH is very similar to that of the O(2)-sensitive standard enzymes except for the proximal Fe-S cluster. Our results give a reasonable explanation why the O(2) tolerance of MBH is attributable to the unique proximal Fe-S cluster; we propose that the cluster is not only a component of the electron transfer for the catalytic cycle, but that it also donates two electrons and one proton crucial for the appropriate reduction of O(2) in preventing the formation of an unready, inactive state of the enzyme. PMID:22002607

  9. North façade, entrance. The square tower has the remains of ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    North façade, entrance. The square tower has the remains of a sign, Kaiser Foundation Hospital. Horizontal ribbon windows continue on this façade. - Richmond Field Hospital, 1330 Cutting Boulevard, Richmond, Contra Costa County, CA

  10. Ligand Binding to the FA3-FA4 Cleft Inhibits the Esterase-Like Activity of Human Serum Albumin

    PubMed Central

    Ascenzi, Paolo; Leboffe, Loris; di Masi, Alessandra; Trezza, Viviana; Fanali, Gabriella; Gioia, Magda; Coletta, Massimo; Fasano, Mauro

    2015-01-01

    The hydrolysis of 4-nitrophenyl esters of hexanoate (NphOHe) and decanoate (NphODe) by human serum albumin (HSA) at Tyr411, located at the FA3-FA4 site, has been investigated between pH 5.8 and 9.5, at 22.0°C. Values of Ks, k+2, and k+2/Ks obtained at [HSA] ≥ 5×[NphOXx] and [NphOXx] ≥ 5×[HSA] (Xx is NphOHe or NphODe) match very well each other; moreover, the deacylation step turns out to be the rate limiting step in catalysis (i.e., k+3 << k+2). The pH dependence of the kinetic parameters for the hydrolysis of NphOHe and NphODe can be described by the acidic pKa-shift of a single amino acid residue, which varies from 8.9 in the free HSA to 7.6 and 7.0 in the HSA:NphOHe and HSA:NphODe complex, respectively; the pK>a-shift appears to be correlated to the length of the fatty acid tail of the substrate. The inhibition of the HSA-Tyr411-catalyzed hydrolysis of NphOHe, NphODe, and 4-nitrophenyl myristate (NphOMy) by five inhibitors (i.e., diazepam, diflunisal, ibuprofen, 3-indoxyl-sulfate, and propofol) has been investigated at pH 7.5 and 22.0°C, resulting competitive. The affinity of diazepam, diflunisal, ibuprofen, 3-indoxyl-sulfate, and propofol for HSA reflects the selectivity of the FA3-FA4 cleft. Under conditions where Tyr411 is not acylated, the molar fraction of diazepam, diflunisal, ibuprofen, and 3-indoxyl-sulfate bound to HSA is higher than 0.9 whereas the molar fraction of propofol bound to HSA is ca. 0.5. PMID:25790235

  11. Opuntia ficus indica (nopal) attenuates hepatic steatosis and oxidative stress in obese Zucker (fa/fa) rats.

    PubMed

    Morán-Ramos, Sofía; Avila-Nava, Azalia; Tovar, Armando R; Pedraza-Chaverri, José; López-Romero, Patricia; Torres, Nimbe

    2012-11-01

    Nonalcoholic fatty liver disease (NAFLD) is associated with multiple factors such as obesity, insulin resistance, and oxidative stress. Nopal, a cactus plant widely consumed in the Mexican diet, is considered a functional food because of its antioxidant activity and ability to improve biomarkers of metabolic syndrome. The aim of this study was to assess the effect of nopal consumption on the development of hepatic steatosis and hepatic oxidative stress and on the regulation of genes involved in hepatic lipid metabolism. Obese Zucker (fa/fa) rats were fed a control diet or a diet containing 4% nopal for 7 wk. Rats fed the nopal-containing diet had ∼50% lower hepatic TG than the control group as well as a reduction in hepatomegaly and biomarkers of hepatocyte injury such as alanine and aspartate aminotransferases. Attenuation of hepatic steatosis by nopal consumption was accompanied by a higher serum concentration of adiponectin and a greater abundance of mRNA for genes involved in lipid oxidation and lipid export and production of carnitine palmitoyltransferase-1 and microsomal TG transfer proteins in liver. Hepatic reactive oxygen species and lipid peroxidation biomarkers were significantly lower in rats fed nopal compared with the control rats. Furthermore, rats fed the nopal diet had a lower postprandial serum insulin concentration and a greater liver phosphorylated protein kinase B (pAKT):AKT ratio in the postprandial state. This study suggests that nopal consumption attenuates hepatic steatosis by increasing fatty acid oxidation and VLDL synthesis, decreasing oxidative stress, and improving liver insulin signaling in obese Zucker (fa/fa) rats. PMID:23014486

  12. Ligand binding to the FA3-FA4 cleft inhibits the esterase-like activity of human serum albumin.

    PubMed

    Ascenzi, Paolo; Leboffe, Loris; di Masi, Alessandra; Trezza, Viviana; Fanali, Gabriella; Gioia, Magda; Coletta, Massimo; Fasano, Mauro

    2015-01-01

    The hydrolysis of 4-nitrophenyl esters of hexanoate (NphOHe) and decanoate (NphODe) by human serum albumin (HSA) at Tyr411, located at the FA3-FA4 site, has been investigated between pH 5.8 and 9.5, at 22.0°C. Values of Ks, k+2, and k+2/Ks obtained at [HSA] ≥ 5×[NphOXx] and [NphOXx] ≥ 5×[HSA] (Xx is NphOHe or NphODe) match very well each other; moreover, the deacylation step turns out to be the rate limiting step in catalysis (i.e., k+3 < k+2). The pH dependence of the kinetic parameters for the hydrolysis of NphOHe and NphODe can be described by the acidic pKa-shift of a single amino acid residue, which varies from 8.9 in the free HSA to 7.6 and 7.0 in the HSA:NphOHe and HSA:NphODe complex, respectively; the pK>a-shift appears to be correlated to the length of the fatty acid tail of the substrate. The inhibition of the HSA-Tyr411-catalyzed hydrolysis of NphOHe, NphODe, and 4-nitrophenyl myristate (NphOMy) by five inhibitors (i.e., diazepam, diflunisal, ibuprofen, 3-indoxyl-sulfate, and propofol) has been investigated at pH 7.5 and 22.0°C, resulting competitive. The affinity of diazepam, diflunisal, ibuprofen, 3-indoxyl-sulfate, and propofol for HSA reflects the selectivity of the FA3-FA4 cleft. Under conditions where Tyr411 is not acylated, the molar fraction of diazepam, diflunisal, ibuprofen, and 3-indoxyl-sulfate bound to HSA is higher than 0.9 whereas the molar fraction of propofol bound to HSA is ca. 0.5. PMID:25790235

  13. Opuntia ficus indica (nopal) attenuates hepatic steatosis and oxidative stress in obese Zucker (fa/fa) rats.

    PubMed

    Morán-Ramos, Sofía; Avila-Nava, Azalia; Tovar, Armando R; Pedraza-Chaverri, José; López-Romero, Patricia; Torres, Nimbe

    2012-11-01

    Nonalcoholic fatty liver disease (NAFLD) is associated with multiple factors such as obesity, insulin resistance, and oxidative stress. Nopal, a cactus plant widely consumed in the Mexican diet, is considered a functional food because of its antioxidant activity and ability to improve biomarkers of metabolic syndrome. The aim of this study was to assess the effect of nopal consumption on the development of hepatic steatosis and hepatic oxidative stress and on the regulation of genes involved in hepatic lipid metabolism. Obese Zucker (fa/fa) rats were fed a control diet or a diet containing 4% nopal for 7 wk. Rats fed the nopal-containing diet had ∼50% lower hepatic TG than the control group as well as a reduction in hepatomegaly and biomarkers of hepatocyte injury such as alanine and aspartate aminotransferases. Attenuation of hepatic steatosis by nopal consumption was accompanied by a higher serum concentration of adiponectin and a greater abundance of mRNA for genes involved in lipid oxidation and lipid export and production of carnitine palmitoyltransferase-1 and microsomal TG transfer proteins in liver. Hepatic reactive oxygen species and lipid peroxidation biomarkers were significantly lower in rats fed nopal compared with the control rats. Furthermore, rats fed the nopal diet had a lower postprandial serum insulin concentration and a greater liver phosphorylated protein kinase B (pAKT):AKT ratio in the postprandial state. This study suggests that nopal consumption attenuates hepatic steatosis by increasing fatty acid oxidation and VLDL synthesis, decreasing oxidative stress, and improving liver insulin signaling in obese Zucker (fa/fa) rats.

  14. FaGAST2, a strawberry ripening-related gene, acts together with FaGAST1 to determine cell size of the fruit receptacle.

    PubMed

    Moyano-Cañete, Enriqueta; Bellido, María L; García-Caparrós, Nicolás; Medina-Puche, Laura; Amil-Ruiz, Francisco; González-Reyes, José A; Caballero, José L; Muñoz-Blanco, Juan; Blanco-Portales, Rosario

    2013-02-01

    Numerous GAST-like genes have been reported in higher plants, but only one GAST-like gene (FaGAST1) has been described in strawberry so far. Herein, we have identified a novel strawberry FaGAST gene (FaGAST2) whose expression showed an increase throughout fruit receptacle development and ripening, coinciding with those stages where a decrease in fruit expansion processes (G3-W and R-OR stages) occurs. FaGAST2 only shares 31% and 15.7% amino acid and nucleotide sequence homology, respectively, with the previously reported FaGAST1 gene, but both genes contain a signal peptide and a highly conserved GASA domain (cysteine-rich domain) in the C-terminal region. FaGAST2 expression is mainly confined to the fruit receptacle and is not regulated by auxins, GA(3) or ABA, but is regulated by ethephon, an intracellular generator of ethylene. In addition, the expression of the FaGAST2 gene also increased under oxidative stress conditions (H(2)O(2) or Colletotrichum acutatum infection), suggesting a direct role for FaGAST2 protein in reactive oxygen species scavenging during fruit growth and ripening and during fungal infection. On the other hand, the overexpression of the FaGAST2 gene in different transgenic lines analyzed caused a delay in the growth of strawberry plants and a reduction in the size of the transgenic fruits. The histological studies performed in these fruits showed that their parenchymal cells were smaller than those of the controls, supporting a relationship between FaGAST2 gene expression, strawberry fruit cell elongation and fruit size. However, transitory silencing of FaGAST2 gene expression through RNA interference approaches revealed an increase in FaGAST1 expression, but no changes in fruit cell size were observed. These results support the hypothesis that both genes must act synergistically to determine fruit cell size during fruit development and ripening.

  15. FaGAST2, a strawberry ripening-related gene, acts together with FaGAST1 to determine cell size of the fruit receptacle.

    PubMed

    Moyano-Cañete, Enriqueta; Bellido, María L; García-Caparrós, Nicolás; Medina-Puche, Laura; Amil-Ruiz, Francisco; González-Reyes, José A; Caballero, José L; Muñoz-Blanco, Juan; Blanco-Portales, Rosario

    2013-02-01

    Numerous GAST-like genes have been reported in higher plants, but only one GAST-like gene (FaGAST1) has been described in strawberry so far. Herein, we have identified a novel strawberry FaGAST gene (FaGAST2) whose expression showed an increase throughout fruit receptacle development and ripening, coinciding with those stages where a decrease in fruit expansion processes (G3-W and R-OR stages) occurs. FaGAST2 only shares 31% and 15.7% amino acid and nucleotide sequence homology, respectively, with the previously reported FaGAST1 gene, but both genes contain a signal peptide and a highly conserved GASA domain (cysteine-rich domain) in the C-terminal region. FaGAST2 expression is mainly confined to the fruit receptacle and is not regulated by auxins, GA(3) or ABA, but is regulated by ethephon, an intracellular generator of ethylene. In addition, the expression of the FaGAST2 gene also increased under oxidative stress conditions (H(2)O(2) or Colletotrichum acutatum infection), suggesting a direct role for FaGAST2 protein in reactive oxygen species scavenging during fruit growth and ripening and during fungal infection. On the other hand, the overexpression of the FaGAST2 gene in different transgenic lines analyzed caused a delay in the growth of strawberry plants and a reduction in the size of the transgenic fruits. The histological studies performed in these fruits showed that their parenchymal cells were smaller than those of the controls, supporting a relationship between FaGAST2 gene expression, strawberry fruit cell elongation and fruit size. However, transitory silencing of FaGAST2 gene expression through RNA interference approaches revealed an increase in FaGAST1 expression, but no changes in fruit cell size were observed. These results support the hypothesis that both genes must act synergistically to determine fruit cell size during fruit development and ripening. PMID:23231876

  16. This NASA Dryden F/A-18 is participating in the Automated Aerial Refueling (AAR) project. F/A-18 (No

    NASA Technical Reports Server (NTRS)

    2002-01-01

    A NASA Dryden F/A-18 is participating in the Automated Aerial Refueling (AAR) project. F/A-18 (No. 847) is acting as an in-flight refueling tanker in the study to develop analytical models for an automated aerial refueling system for unmanned vehicles. A 300-gallon aerodynamic pod containing air-refueling equipment is seen beneath the fuselage. The hose and refueling basket are extended during an assessment of their dynamics on the F/A-18A.

  17. FaPOD27 functions in the metabolism of polyphenols in strawberry fruit (Fragaria sp.).

    PubMed

    Yeh, Su-Ying; Huang, Fong-Chin; Hoffmann, Thomas; Mayershofer, Mechthild; Schwab, Wilfried

    2014-01-01

    The strawberry (Fragaria × ananassa) is one of the most preferred fresh fruit worldwide, accumulates numerous flavonoids but has limited shelf life due to excessive tissue softening caused by cell wall degradation. Since lignin is one of the polymers that strengthen plant cell walls and might contribute to some extent to fruit firmness monolignol biosynthesis was studied in strawberry fruit. Cinnamoyl-CoA reductase (CCR), cinnamyl alcohol dehydrogenase (CAD), and a peroxidase (POD27) gene were strongly expressed in red, ripe fruit whereas a second POD gene was primarily expressed in green, immature fruit. Moreover, FaPOD27 transcripts were strongly and constitutively induced in fruits exposed to Agrobacterium infection. Gene expression levels and enzymatic activities of FaCCR and FaCAD were efficiently suppressed through RNAi in FaCCR- and FaCAD-silenced strawberries. Besides, significantly elevated FaPOD transcript levels were detected after agroinfiltration of pBI-FaPOD constructs in fruits. At the same time, levels of G-monomers were considerably reduced in FaCCR-silenced fruits whereas the proportion of both G- and S-monomers decisively decreased in FaCAD-silenced and pBI-FaPOD fruits. Development, firmness, and lignin level of the treated fruits were similar to pBI-intron control fruits, presumably attributed to increased expression levels of FaPOD27 upon agroinfiltration. Additionally, enhanced firmness, accompanied with elevated lignin levels, was revealed in chalcone synthase-deficient fruits (CHS(-)), independent of down- or up-regulation of individual and combined FaCCR. FaCAD, and FaPOD genes by agroinfiltration, when compared to CHS(-)/pBI-intron control fruits. These approaches provide further insight into the genetic control of flavonoid and lignin synthesis in strawberries. The results suggest that FaPOD27 is a key gene for lignin biosynthesis in strawberry fruit and thus to improving the firmness of strawberries. PMID:25346738

  18. Whole exome sequencing reveals concomitant mutations of multiple FA genes in individual Fanconi anemia patients

    PubMed Central

    2014-01-01

    Background Fanconi anemia (FA) is a rare inherited genetic syndrome with highly variable clinical manifestations. Fifteen genetic subtypes of FA have been identified. Traditional complementation tests for grouping studies have been used generally in FA patients and in stepwise methods to identify the FA type, which can result in incomplete genetic information from FA patients. Methods We diagnosed five pediatric patients with FA based on clinical manifestations, and we performed exome sequencing of peripheral blood specimens from these patients and their family members. The related sequencing data were then analyzed by bioinformatics, and the FANC gene mutations identified by exome sequencing were confirmed by PCR re-sequencing. Results Homozygous and compound heterozygous mutations of FANC genes were identified in all of the patients. The FA subtypes of the patients included FANCA, FANCM and FANCD2. Interestingly, four FA patients harbored multiple mutations in at least two FA genes, and some of these mutations have not been previously reported. These patients’ clinical manifestations were vastly different from each other, as were their treatment responses to androstanazol and prednisone. This finding suggests that heterozygous mutation(s) in FA genes could also have diverse biological and/or pathophysiological effects on FA patients or FA gene carriers. Interestingly, we were not able to identify de novo mutations in the genes implicated in DNA repair pathways when the sequencing data of patients were compared with those of their parents. Conclusions Our results indicate that Chinese FA patients and carriers might have higher and more complex mutation rates in FANC genes than have been conventionally recognized. Testing of the fifteen FANC genes in FA patients and their family members should be a regular clinical practice to determine the optimal care for the individual patient, to counsel the family and to obtain a better understanding of FA pathophysiology

  19. FaPOD27 functions in the metabolism of polyphenols in strawberry fruit (Fragaria sp.).

    PubMed

    Yeh, Su-Ying; Huang, Fong-Chin; Hoffmann, Thomas; Mayershofer, Mechthild; Schwab, Wilfried

    2014-01-01

    The strawberry (Fragaria × ananassa) is one of the most preferred fresh fruit worldwide, accumulates numerous flavonoids but has limited shelf life due to excessive tissue softening caused by cell wall degradation. Since lignin is one of the polymers that strengthen plant cell walls and might contribute to some extent to fruit firmness monolignol biosynthesis was studied in strawberry fruit. Cinnamoyl-CoA reductase (CCR), cinnamyl alcohol dehydrogenase (CAD), and a peroxidase (POD27) gene were strongly expressed in red, ripe fruit whereas a second POD gene was primarily expressed in green, immature fruit. Moreover, FaPOD27 transcripts were strongly and constitutively induced in fruits exposed to Agrobacterium infection. Gene expression levels and enzymatic activities of FaCCR and FaCAD were efficiently suppressed through RNAi in FaCCR- and FaCAD-silenced strawberries. Besides, significantly elevated FaPOD transcript levels were detected after agroinfiltration of pBI-FaPOD constructs in fruits. At the same time, levels of G-monomers were considerably reduced in FaCCR-silenced fruits whereas the proportion of both G- and S-monomers decisively decreased in FaCAD-silenced and pBI-FaPOD fruits. Development, firmness, and lignin level of the treated fruits were similar to pBI-intron control fruits, presumably attributed to increased expression levels of FaPOD27 upon agroinfiltration. Additionally, enhanced firmness, accompanied with elevated lignin levels, was revealed in chalcone synthase-deficient fruits (CHS(-)), independent of down- or up-regulation of individual and combined FaCCR. FaCAD, and FaPOD genes by agroinfiltration, when compared to CHS(-)/pBI-intron control fruits. These approaches provide further insight into the genetic control of flavonoid and lignin synthesis in strawberries. The results suggest that FaPOD27 is a key gene for lignin biosynthesis in strawberry fruit and thus to improving the firmness of strawberries.

  20. FaPOD27 functions in the metabolism of polyphenols in strawberry fruit (Fragaria sp.)

    PubMed Central

    Yeh, Su-Ying; Huang, Fong-Chin; Hoffmann, Thomas; Mayershofer, Mechthild; Schwab, Wilfried

    2014-01-01

    The strawberry (Fragaria × ananassa) is one of the most preferred fresh fruit worldwide, accumulates numerous flavonoids but has limited shelf life due to excessive tissue softening caused by cell wall degradation. Since lignin is one of the polymers that strengthen plant cell walls and might contribute to some extent to fruit firmness monolignol biosynthesis was studied in strawberry fruit. Cinnamoyl-CoA reductase (CCR), cinnamyl alcohol dehydrogenase (CAD), and a peroxidase (POD27) gene were strongly expressed in red, ripe fruit whereas a second POD gene was primarily expressed in green, immature fruit. Moreover, FaPOD27 transcripts were strongly and constitutively induced in fruits exposed to Agrobacterium infection. Gene expression levels and enzymatic activities of FaCCR and FaCAD were efficiently suppressed through RNAi in FaCCR- and FaCAD-silenced strawberries. Besides, significantly elevated FaPOD transcript levels were detected after agroinfiltration of pBI-FaPOD constructs in fruits. At the same time, levels of G-monomers were considerably reduced in FaCCR-silenced fruits whereas the proportion of both G- and S-monomers decisively decreased in FaCAD-silenced and pBI-FaPOD fruits. Development, firmness, and lignin level of the treated fruits were similar to pBI-intron control fruits, presumably attributed to increased expression levels of FaPOD27 upon agroinfiltration. Additionally, enhanced firmness, accompanied with elevated lignin levels, was revealed in chalcone synthase-deficient fruits (CHS−), independent of down- or up-regulation of individual and combined FaCCR. FaCAD, and FaPOD genes by agroinfiltration, when compared to CHS−/pBI-intron control fruits. These approaches provide further insight into the genetic control of flavonoid and lignin synthesis in strawberries. The results suggest that FaPOD27 is a key gene for lignin biosynthesis in strawberry fruit and thus to improving the firmness of strawberries. PMID:25346738

  1. Characteristics of F/A-18 vertical tail buffeting

    NASA Astrophysics Data System (ADS)

    Sheta, E. F.; Huttsell, L. J.

    2003-03-01

    A time-accurate computational analysis of vertical tail buffeting of full F/A-18 aircraft is conducted at typical flight conditions to identify the buffet characteristics of fighter aircraft. The F/A-18 aircraft is pitched at wide range of high angles of attack at Mach number of 0.243 and Reynolds number of 11 millions. Strong coupling between the fluid and structure is considered in this investigation. Strong coupling occurs when the inertial effect of the motion of the vertical tail is fed back into the flow field. The aerodynamic flow field around the F/A-18 aircraft is computed using the Reynolds-averaged full Navier-Stokes equations. The dynamical structural response of the vertical tail is predicted using direct finite-element analysis. The interface between the fluid and structure is applied using conservative and consistent interfacing methodology. The motion of the computational grid due to the deflection of the vertical tail is computed using transfinite interpolation module. The investigation revealed that the vertical tail is subject to bending and torsional responses, mainly in the first modes of vibrations. The buffet loads increase significantly as the onset of vortex breakdown moves upstream of the vertical tails. The inboard surface of the vertical tail has more significant contribution in the buffet excitation than the outboard surface. In addition, the pressure on the outboard surface of the vertical tail is less sensitive to the angle of attack than the pressure on the inboard surface. The buffet excitation peaks shift to lower frequency as the angle of attack increases. The computational results are compared, and they are in close agreement, with several flight and experimental data.

  2. Basic firefly algorithm for document clustering

    NASA Astrophysics Data System (ADS)

    Mohammed, Athraa Jasim; Yusof, Yuhanis; Husni, Husniza

    2015-12-01

    The Document clustering plays significant role in Information Retrieval (IR) where it organizes documents prior to the retrieval process. To date, various clustering algorithms have been proposed and this includes the K-means and Particle Swarm Optimization. Even though these algorithms have been widely applied in many disciplines due to its simplicity, such an approach tends to be trapped in a local minimum during its search for an optimal solution. To address the shortcoming, this paper proposes a Basic Firefly (Basic FA) algorithm to cluster text documents. The algorithm employs the Average Distance to Document Centroid (ADDC) as the objective function of the search. Experiments utilizing the proposed algorithm were conducted on the 20Newsgroups benchmark dataset. Results demonstrate that the Basic FA generates a more robust and compact clusters than the ones produced by K-means and Particle Swarm Optimization (PSO).

  3. Depositional Environment of Permian Tak Fa Formation, Nakhonsawan, Northern Thailand

    NASA Astrophysics Data System (ADS)

    Ketwetsuriya, Chatchalerm; Nützel, Alexander; Kanjanapayont, Pitsanupong

    2016-04-01

    The carbonate rocks of the study area at Amphoe Tak Fa and Amphoe Takhli, Changwat Nakhon Sawan belong to the Tak Fa Formation, Saraburi Group. This formation crops out in the Khao Khwang Platform and consists of late Palaeozoic carbonate platform deposits. It reaches a thickness of 900 meters and crops out in a vast area. The exposures have been measured and samples were collected for petrographic study. The rock consists of limestones, argillaceous limestones, mudstones and dolomites with nodular and banded cherts, which comprise many invertebrate fossils such as fusulinids, ammonoid, pelecypod, gastropod, coral and bryozoa. Many of the fossils are silicified. The gastropod assemblage is currently under study and represents one of the most diverse faunas reported from SE Asia. The age of the rock is Yakhtashian or Artinskian (late Early Permian) to Midian or Capitanian (late Middle Permian). The study of carbonate facies and fauna indicates that the depositional environment was on shelf lagoon within the carbonate platform varying from shallow marine to barrier bar.

  4. Biochemical and spectroscopic studies of epoxyqueuosine reductase: A novel iron-sulfur cluster and cobalamin containing protein involved in the biosynthesis of queuosine

    PubMed Central

    Miles, Zachary D.; Myers, William K.; Kincannon, William M.; Britt, R. David; Bandarian, Vahe

    2015-01-01

    Queuosine is a hypermodified nucleoside present in the wobble position of tRNAs with a 5′-GUN-3′ sequence in their anticodon (His, Asp, Asn, and Tyr). The 7-deazapurine core of the base is synthesized de novo in prokaryotes from guanosine-5′-triphosphate in a series of eight sequential enzymatic transformations, the final three occurring on tRNA. Epoxyqueuosine reductase (QueG), catalyzes the final step in the pathway, which entails the 2-electron reduction of epoxyqueuosine to form queuosine. Biochemical analyses reveal that this enzyme requires cobalamin and two [4Fe-4S] clusters for catalysis. Spectroscopic studies show that the cobalamin appears to bind in a base-off conformation, whereby the dimethylbenzimidazole moiety of the cofactor is removed from the coordination sphere of the cobalt but not replaced by an imidazole sidechain, which is a hallmark of many cobalamin-dependent enzymes. The bioinformatically-identified residues are shown to have a role in modulating the primary coordination sphere of cobalamin. These studies provide the first demonstration of the cofactor requirements for QueG. PMID:26230193

  5. Crystal structure of a prokaryotic (6-4) photolyase with an Fe-S cluster and a 6,7-dimethyl-8-ribityllumazine antenna chromophore.

    PubMed

    Zhang, Fan; Scheerer, Patrick; Oberpichler, Inga; Lamparter, Tilman; Krauß, Norbert

    2013-04-30

    The (6-4) photolyases use blue light to reverse UV-induced (6-4) photoproducts in DNA. This (6-4) photorepair was thought to be restricted to eukaryotes. Here we report a prokaryotic (6-4) photolyase, PhrB from Agrobacterium tumefaciens, and propose that (6-4) photolyases are broadly distributed in prokaryotes. The crystal structure of photolyase related protein B (PhrB) at 1.45 Å resolution suggests a DNA binding mode different from that of the eukaryotic counterparts. A His-His-X-X-Arg motif is located within the proposed DNA lesion contact site of PhrB. This motif is structurally conserved in eukaryotic (6-4) photolyases for which the second His is essential for the (6-4) photolyase function. The PhrB structure contains 6,7-dimethyl-8-ribityllumazine as an antenna chromophore and a [4Fe-4S] cluster bound to the catalytic domain. A significant part of the Fe-S fold strikingly resembles that of the large subunit of eukaryotic and archaeal primases, suggesting that the PhrB-like photolyases branched at the base of the evolution of the cryptochrome/photolyase family. Our study presents a unique prokaryotic (6-4) photolyase and proposes that the prokaryotic (6-4) photolyases are the ancestors of the cryptochrome/photolyase family.

  6. Biochemical and Spectroscopic Studies of Epoxyqueuosine Reductase: A Novel Iron-Sulfur Cluster- and Cobalamin-Containing Protein Involved in the Biosynthesis of Queuosine.

    PubMed

    Miles, Zachary D; Myers, William K; Kincannon, William M; Britt, R David; Bandarian, Vahe

    2015-08-11

    Queuosine is a hypermodified nucleoside present in the wobble position of tRNAs with a 5'-GUN-3' sequence in their anticodon (His, Asp, Asn, and Tyr). The 7-deazapurine core of the base is synthesized de novo in prokaryotes from guanosine 5'-triphosphate in a series of eight sequential enzymatic transformations, the final three occurring on tRNA. Epoxyqueuosine reductase (QueG) catalyzes the final step in the pathway, which entails the two-electron reduction of epoxyqueuosine to form queuosine. Biochemical analyses reveal that this enzyme requires cobalamin and two [4Fe-4S] clusters for catalysis. Spectroscopic studies show that the cobalamin appears to bind in a base-off conformation, whereby the dimethylbenzimidazole moiety of the cofactor is removed from the coordination sphere of the cobalt but not replaced by an imidazole side chain, which is a hallmark of many cobalamin-dependent enzymes. The bioinformatically identified residues are shown to have a role in modulating the primary coordination sphere of cobalamin. These studies provide the first demonstration of the cofactor requirements for QueG.

  7. Occurrence of Far-Red Light Photoacclimation (FaRLiP) in Diverse Cyanobacteria

    PubMed Central

    Gan, Fei; Shen, Gaozhong; Bryant, Donald A.

    2014-01-01

    Cyanobacteria have evolved a number of acclimation strategies to sense and respond to changing nutrient and light conditions. Leptolyngbya sp. JSC-1 was recently shown to photoacclimate to far-red light by extensively remodeling its photosystem (PS) I, PS II and phycobilisome complexes, thereby gaining the ability to grow in far-red light. A 21-gene photosynthetic gene cluster (rfpA/B/C, apcA2/B2/D2/E2/D3, psbA3/D3/C2/B2/H2/A4, psaA2/B2/L2/I2/F2/J2) that is specifically expressed in far-red light encodes the core subunits of the three major photosynthetic complexes. The growth responses to far-red light were studied here for five additional cyanobacterial strains, each of which has a gene cluster similar to that in Leptolyngbya sp. JSC-1. After acclimation all five strains could grow continuously in far-red light. Under these growth conditions each strain synthesizes chlorophylls d, f and a after photoacclimation, and each strain produces modified forms of PS I, PS II (and phycobiliproteins) that absorb light between 700 and 800 nm. We conclude that these photosynthetic gene clusters are diagnostic of the capacity to photoacclimate to and grow in far-red light. Given the diversity of terrestrial environments from which these cyanobacteria were isolated, it is likely that FaRLiP plays an important role in optimizing photosynthesis in terrestrial environments. PMID:25551681

  8. Effects of intracerebroventricularly and intraperitoneally administered growth hormone on body weight and food intake in fa/fa Zucker rats.

    PubMed

    Schulz, Carla; Wieczorek, Ingo; Reschke, Kirsten; Lehnert, Hendrik

    2002-01-01

    Growth hormone (GH) possesses multiple metabolic effects, in particular with regard to glucose and lipid homeostasis. Studies on the effects of GH on body weight and food and water intake are scarce and have yielded controversial results. We investigated the effects of different modes of GH administration on the parameters of body weight and food intake as well as on insulin and leptin concentrations in fa/fa Zucker rats. In control experiments, aqua pro injection was given. GH was administered over a time period of 11 days at a daily dose of 250 microg intraperitoneally (i.p.) and 25 microg intracerebroventricularly (i.c.v.). While both food intake and body weight were found to be unaltered in the four groups after this observation period, there was an enhanced food intake and consecutively an increase in body weight over the day period when compared to the night period in the groups of rats that received GH i.c.v. or i.p. This tendency was also shown for water intake. Insulin and leptin concentrations were similar in all groups. Thus, injection of GH appears to modify food intake-related behavior, since the periods of enhanced food and water intake were shifted from night- to daytime. Thus, while in general the metabolic parameters remained unchanged, the activity pattern was clearly modified.

  9. Analysis of Tyr to Phe and fa/fa leptin receptor mutations in the PC12 cell line.

    PubMed

    Eyckerman, S; Waelput, W; Verhee, A; Broekaert, D; Vandekerckhove, J; Tavernier, J

    1999-12-01

    Weight regulation through body-fat content and energy homeostasis, is regulated mainly through the actions of leptin. Herein, we analyse the effect of mutations in the mouse leptin receptor using the PC12 pheochromocytoma cell line as a model system. Both the induction of pancreatitis associated protein 1 and metallothionein-II, two leptin regulated genes in PC12, was evaluated. Tyr to Phe mutations in the cytoplasmic tail of the mouse leptin receptor confirmed the critical role of Tyr1138 (a YxxQ motif) and STAT-3 activation for induction of leptin-induced genes in PC12. In addition, the Tyr985Phe mutation showed enhanced responsiveness to leptin, which was even more pronounced in combination with Tyr1077Phe. The short isoform of the leptin receptor showed complete loss of stimulation of both genes. In contrast, a leptin receptor devoid of all Tyr residues in its cytoplasmic tail was still capable of a limited induction of the PAP 1 gene. A mutant mouse leptin receptor containing the fa/fa mutation showed constitutive signalling and impaired responsiveness to leptin. Treatment with the adenylate cyclase activator forskolin alone, in the absence of leptin was sufficient to obtain full induction of both genes. PMID:10586122

  10. Effects of chronic celiprolol treatment on brown fat, feeding, and drinking in fa/fa Zucker rats.

    PubMed

    Savontaus, E; Rouru, J; Malminiemi, K; Luukkaa, V; Pesonen, U; Koulu, M; Huupponen, R

    2000-04-01

    Celiprolol is a novel beta-adrenoceptor blocking drug that displays clinically favorable effects on glucose and lipid metabolism. Because some other atypical beta-adrenoceptor blocking drugs have been described to act as agonists on beta(3)-adrenoceptors, we aimed to investigate the effects of celiprolol on brown fat and beta(3)-adrenoceptors. Chronic treatment of obese fa/fa Zucker rats with celiprolol (50 mg/kg/day orally for 20 days) increased GDP binding to brown fat mitochondria by 1.5-fold, whereas beta(3)-adrenoceptor agonist ZD7114 ((S)-4-[2-[(2-hydroxy-3-phenoxypropyl)amino]ethoxy]-N-(2-methoxyet hyl )phenoxyacetamide, 3 mg/kg/day) increased the binding by 3.3-fold. Weight gain was reduced by 19% due to decreased water and food intakes in celiprolol-treated rats. Celiprolol did not activate lipolysis in rat adipocytes in vitro or stimulate human beta(3)-adrenoceptors expressed in Chinese hamster ovary cells as measured with Cytosensor microphysiometer. Therefore, celiprolol does not seem to activate brown fat via beta(3)-adrenoceptors. PMID:10764928

  11. α1-Tubulin FaTuA1 plays crucial roles in vegetative growth and conidiation in Fusarium asiaticum.

    PubMed

    Hu, Weiqun; Zhang, Xiaoping; Chen, Xiang; Zheng, Jingwu; Yin, Yanni; Ma, Zhonghua

    2015-04-01

    The filamentous ascomycete Fusarium asiaticum contains two homologous genes FaTUA1 and FaTUA2 encoding α-tubulins. In this study, we found that FaTUA2 was dispensable for vegetative growth and sporulation in F. asiaticum. The deletion of FaTUA1 however led to dramatically reduced mycelial growth, twisted hyphae and abnormal nuclei in apical cells of hyphae. The FaTUA1 deletion mutant (ΔFaTuA1-5) also showed a significant decrease in conidiation, and produced abnormal conidia. Pathogenicity assays showed that ΔFaTuA1-5 exhibited decreased virulence on wheat head. Unexpectedly, the deletion of FaTUA1 led to resistance to high temperatures. In addition, ΔFaTuA2 showed increased sensitivity to carbendazim. Furthermore, increased FaTUA2 expression in ΔFaTuA1-5 partially restored the defects of the mutant in mycelial growth, conidial production and virulence, vice versa, increased FaTUA1 expression in the FaTUA2 deletion mutant also partially relieved the defect of the mutant in the delay of conidial germination. Taken together, these results indicate that FaTuA1 plays crucial roles in vegetative growth and development, and the functions of FaTuA1 and FaTuA2 are partially interchangeable in F. asiaticum.

  12. Involvement of fertilization antigen (FA-1) in involuntary immunoinfertility in humans.

    PubMed Central

    Naz, R K

    1987-01-01

    Sera from immunoinfertile patients (n = 32) and fertile controls (n = 20) were analyzed for cross-reaction with a purified and characterized sperm-specific glycoprotein, the fertilization antigen (FA-1), employing an enzyme-linked immunosorbent assay. The immunoinfertile sera demonstrated a strong reaction with FA-1 when compared with fertile control sera. There was no correlation between the reaction of sera with FA-1 and the titers obtained through the sperm agglutination technique and the sperm immobilization technique. Immunoinfertile sera showed binding with the protein bands in the regions corresponding to FA-1 on Western blots involving sodium deoxycholate-solubilized human sperm. Antigens isolated with immunoaffinity chromatography involving immunoinfertile sera also demonstrated antigen bands corresponding to FA-1 in sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Of the seven immunoinfertile couples, three that had antibodies to FA-1 in the male as well as female partners demonstrated a block of fertilization (IVF) due to antibodies bound on the sperm surface. The anti-FA-1 antibody activity was detected in serum as well as in follicular fluid and seminal plasma. Immunoinfertile sera that showed an inhibition of human sperm penetration of zona-free hamster ova showed a significant (P less than 0.001) increase in penetration rates after absorption with FA-1. These results indicate that sera from immunoinfertile patients had antibodies reacting with FA-1, and these antibodies are involved in the fertilization process. Images PMID:3316276

  13. Multiple defects occur in the guanine nucleotide regulatory protein system in liver plasma membranes of obese (fa/fa) but not lean (Fa/Fa) Zucker rats: loss of functional Gi and abnormal Gs function.

    PubMed

    Houslay, M D; Gawler, D J; Milligan, G; Wilson, A

    1989-01-01

    suggested that abnormalities in the levels of expression of primarily the 52 kDa form of alpha-Gs may give rise to the abnormal coupling between glucagon receptors and adenylate cyclase in liver membranes from obese (fa/fa) Zucker rats. PMID:2561940

  14. Physical Demands of Different Positions in FA Premier League Soccer.

    PubMed

    Bloomfield, Jonathan; Polman, Remco; O'Donoghue, Peter

    2007-01-01

    The purpose of this study was to evaluate the physical demands of English Football Association (FA) Premier League soccer of three different positional classifications (defender, midfielder and striker). Computerised time-motion video-analysis using the Bloomfield Movement Classification was undertaken on the purposeful movement (PM) performed by 55 players. Recognition of PM had a good inter-tester reliability strength of agreement (κ= 0.7277). Players spent 40.6 ± 10.0% of the match performing PM. Position had a significant influence on %PM time spent sprinting, running, shuffling, skipping and standing still (p < 0.05). However, position had no significant influence on the %PM time spent performing movement at low, medium, high or very high intensities (p > 0.05). Players spent 48.7 ± 9.2% of PM time moving in a directly forward direction, 20.6 ± 6.8% not moving in any direction and the remainder of PM time moving backward, lateral, diagonal and arced directions. The players performed the equivalent of 726 ± 203 turns during the match; 609 ± 193 of these being of 0° to 90° to the left or right. Players were involved in the equivalent of 111 ± 77 on the ball movement activities per match with no significant differences between the positions for total involvement in on the ball activity (p > 0.05). This study has provided an indication of the different physical demands of different playing positions in FA Premier League match-play through assessment of movements performed by players. Key pointsPlayers spent ~40% of the match performing Pur-poseful Movement (PM).Position had a significant influence on %PM time spent performing each motion class except walking and jogging. Players performed >700 turns in PM, most of these being of 0°-90°.Strikers performed most high to very high intensity activity and most contact situations.Defenders also spent a significantly greater %PM time moving backwards than the other two posi-tions.Different positions could

  15. FaRP cell distribution in the developing CNS suggests the involvement of FaRPs in all parts of the chromatophore control pathway in Sepia officinalis (Cephalopoda).

    PubMed

    Aroua, Salima; Andouche, Aude; Martin, Madeleine; Baratte, Sébastien; Bonnaud, Laure

    2011-04-01

    The FMRFamide-related peptide (FaRP) family includes a wide range of neuropeptides that have a role in many biological functions. In cephalopods, these peptides intervene in the peculiar body patterning system used for communication and camouflage. This system is particularly well developed in the cuttlefish and is functional immediately after hatching (stage 30). In this study, we investigate when and how the neural structures involved in the control of body patterning emerge and combine during Sepia embryogenesis, by studying the expression or the production of FaRPs. We detected FaRP expression and production in the nervous system of embryos from the beginning of organogenesis (stage 16). The wider FaRP expression was observed concomitantly with brain differentiation (around stage 22). Until hatching, FaRP-positive cells were located in specific areas of the central and peripheral nervous system (CNS and PNS). Most of these areas were implicated in the control of body patterns, suggesting that FaRPs are involved in all parts of the neural body pattern control system, from the 'receptive areas' via the CNS to the chromatophore effectors.

  16. RfpA, RfpB, and RfpC are the master control elements of far-red light photoacclimation (FaRLiP)

    DOE PAGES

    Zhao, Chi; Gan, Fei; Shen, Gaozhong; Bryant, Donald A.

    2015-11-25

    Terrestrial cyanobacteria often occur in niches tha tare strongly enriched in far-redlight (FRL; λ > 700nm). Some cyanobacteria exhibit a complex and extensive photoacclimation response, known as FRLphotoacclimation(FaRLiP).During the FaRLiP response, specialized paralogous proteins replace 17 core subunits of the three major photosynthetic complexes: Photosystem (PS)I, PSII,and the phycobilisome. Additionally, the cells synthesize both chlorophyll (Chl) f and Chl d.Using biparental mating from Escherichia coli, we constructed null mutants of three genes, rfpA, rfpB,and rfpC, in the cyanobacteria Chlorogloeopsis fritschii PCC 9212 and Chroococcidiopsis thermalis PCC 7203.The resulting mutants were no longer able to modify their photosynthetic apparatus to absorbmore » FRL, were no longer able to synthesize Chl f, in appropriately synthesized Chl d in white light,and were unable to transcribe genes of the FaRLiP gene cluster. We conclude that RfpA, RfpB, and RfpC constitute a FRL-activated signal transduction cascade that is the master control switch for the FaRLiP response. FRL is proposed to activate (or inactivate) the histidine kinase activity of RfpA, which leads to formation of the active state of RfpB, the key response regulator and transcription activator. RfpC may act as a phosphate shuttle between RfpA and RfpB. Our results show that reverse genetics via conjugation will be a powerful approach in detailed studies of the FaRLiP response.« less

  17. RfpA, RfpB, and RfpC are the master control elements of far-red light photoacclimation (FaRLiP)

    SciTech Connect

    Zhao, Chi; Gan, Fei; Shen, Gaozhong; Bryant, Donald A.

    2015-11-25

    Terrestrial cyanobacteria often occur in niches tha tare strongly enriched in far-redlight (FRL; λ > 700nm). Some cyanobacteria exhibit a complex and extensive photoacclimation response, known as FRLphotoacclimation(FaRLiP).During the FaRLiP response, specialized paralogous proteins replace 17 core subunits of the three major photosynthetic complexes: Photosystem (PS)I, PSII,and the phycobilisome. Additionally, the cells synthesize both chlorophyll (Chl) f and Chl d.Using biparental mating from Escherichia coli, we constructed null mutants of three genes, rfpA, rfpB,and rfpC, in the cyanobacteria Chlorogloeopsis fritschii PCC 9212 and Chroococcidiopsis thermalis PCC 7203.The resulting mutants were no longer able to modify their photosynthetic apparatus to absorb FRL, were no longer able to synthesize Chl f, in appropriately synthesized Chl d in white light,and were unable to transcribe genes of the FaRLiP gene cluster. We conclude that RfpA, RfpB, and RfpC constitute a FRL-activated signal transduction cascade that is the master control switch for the FaRLiP response. FRL is proposed to activate (or inactivate) the histidine kinase activity of RfpA, which leads to formation of the active state of RfpB, the key response regulator and transcription activator. RfpC may act as a phosphate shuttle between RfpA and RfpB. Our results show that reverse genetics via conjugation will be a powerful approach in detailed studies of the FaRLiP response.

  18. RfpA, RfpB, and RfpC are the Master Control Elements of Far-Red Light Photoacclimation (FaRLiP)

    PubMed Central

    Zhao, Chi; Gan, Fei; Shen, Gaozhong; Bryant, Donald A.

    2015-01-01

    Terrestrial cyanobacteria often occur in niches that are strongly enriched in far-red light (FRL; λ > 700 nm). Some cyanobacteria exhibit a complex and extensive photoacclimation response, known as FRL photoacclimation (FaRLiP). During the FaRLiP response, specialized paralogous proteins replace 17 core subunits of the three major photosynthetic complexes: Photosystem (PS) I, PS II, and the phycobilisome. Additionally, the cells synthesize both chlorophyll (Chl) f and Chl d. Using biparental mating from Escherichia coli, we constructed null mutants of three genes, rfpA, rfpB, and rfpC, in the cyanobacteria Chlorogloeopsis fritschii PCC 9212 and Chroococcidiopsis thermalis PCC 7203. The resulting mutants were no longer able to modify their photosynthetic apparatus to absorb FRL, were no longer able to synthesize Chl f, inappropriately synthesized Chl d in white light, and were unable to transcribe genes of the FaRLiP gene cluster. We conclude that RfpA, RfpB, and RfpC constitute a FRL-activated signal transduction cascade that is the master control switch for the FaRLiP response. FRL is proposed to activate (or inactivate) the histidine kinase activity of RfpA, which leads to formation of the active state of RfpB, the key response regulator and transcription activator. RfpC may act as a phosphate shuttle between RfpA and RfpB. Our results show that reverse genetics via conjugation will be a powerful approach in detailed studies of the FaRLiP response. PMID:26635768

  19. Exterior building details of Building D, east façade: painted concrete ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Exterior building details of Building D, east façade: painted concrete east face façade, main entry has flat cement plaster surround, double door six light over panels, two light transom over double door; westerly view - San Quentin State Prison, Building 22, Point San Quentin, San Quentin, Marin County, CA

  20. Symbolic clustering

    SciTech Connect

    Reinke, R.E.

    1991-01-01

    Clustering is the problem of finding a good organization for data. Because there are many kinds of clustering problems, and because there are many possible clusterings for any data set, clustering programs use knowledge and assumptions about individual problems to make clustering tractable. Cluster-analysis techniques allow knowledge to be expressed in the choice of a pairwise distance measure and in the choice of clustering algorithm. Conceptual clustering adds knowledge and preferences about cluster descriptions. In this study the author describes symbolic clustering, which adds representation choice to the set of ways a data analyst can use problem-specific knowledge. He develops an informal model for symbolic clustering, and uses it to suggest where and how knowledge can be expressed in clustering. A language for creating symbolic clusters, based on the model, was developed and tested on three real clustering problems. The study concludes with a discussion of the implications of the model and the results for clustering in general.

  1. Proinflammatory gene expression and renal lipogenesis are modulated by dietary protein content in obese Zucker fa/fa rats.

    PubMed

    Tovar-Palacio, Claudia; Tovar, Armando R; Torres, Nimbe; Cruz, Cristino; Hernández-Pando, Rogelio; Salas-Garrido, Gerardo; Pedraza-Chaverri, José; Correa-Rotter, Ricardo

    2011-01-01

    Obesity is a risk factor for the development of chronic kidney disease (CKD) and end-stage renal disease. It is not clear whether the adoption of a high-protein diet in obese patients affects renal lipid metabolism or kidney function. Thus the aims of this study were to assess in obese Zuckerfa/fa rats the effects of different types and amounts of dietary protein on the expression of lipogenic and inflammatory genes, as well as renal lipid concentration and biochemical parameters of kidney function. Rats were fed different concentrations of soy protein or casein (20, 30, 45%) for 2 mo. Independent of the type of protein ingested, higher dietary protein intake led to higher serum triglycerides (TG) than rats fed adequate concentrations of protein. Additionally, the soy protein diet significantly increased serum TG compared with the casein diet. However, rats fed soy protein had significantly decreased serum cholesterol concentrations compared with those fed a casein diet. No significant differences in renal TG and cholesterol concentrations were observed between rats fed with either protein diets. Renal expression of sterol-regulatory element binding protein 2 (SREBP-2) and its target gene HMG-CoA reductase was significantly increased as the concentration of dietary protein increased. The highest protein diets were associated with greater expression of proinflammatory cytokines in the kidney, independent of the type of dietary protein. These results indicate that high soy or casein protein diets upregulate the expression of lipogenic and proinflammatory genes in the kidney.

  2. Lipase-catalyzed hydrolysis of TG containing acetylenic FA.

    PubMed

    Jie, Marcel S F Lie Ken; Fua, Xun; Lau, Maureen M L; Chye, M L

    2002-10-01

    Hydrolysis of symmetrical acetylenic TG of type AAA [viz., glycerol tri-(4-decynoate), glycerol tri-(6-octadecynoate), glycerol tri-(9-octadecynoate), glycerol tri-(10-undecynoate), and glycerol tri-(13-docosynoate)] in the presence of eight microbial lipases was studied. Novozyme 435 (Candida antarctica), an efficient enzyme for esterification, showed a significant resistance in the hydrolysis of glycerol tri-(9-octadecynoate) and glycerol tri-(13-docosynoate). Hydrolysis of acetylenic TG with Lipolase 100T (Humicola lanuginosa) was rapidly accomplished. Lipase PS-D (Pseudomonas cepacia) showed a fair resistance toward the hydrolysis of glycerol tri-(6-octadecynoate) only, which reflected its ability to recognize the delta6 positional isomer of 18:1. Lipase CCL (Candida cylindracea, syn. C. rugosa) and AY-30 (C. rugosa) were able to catalyze the release of 10-undecynoic acid and 9-octadecynoic acid from the corresponding TG, but less readily the 13-docosynoic acid in the case of glycerol tri-(13-docosynoate). The two lipases CCL and AY-30 were able to distinguish the small difference in structure of fatty acyl moieties in the TG substrate. To confirm this trend, three regioisomers of mixed acetylenic TG of type ABC (containing one each of delta6, delta9, and delta13 acetylenic FA in various positions) were prepared and hydrolyzed with CCL and AY-40. The results reconfirmed the observation that AY-30 and CCL were able to distinguish the slight differences in the molecular structure (position of the acetylenic bond and chain length) of the acyl groups in the TG during the hydrolysis of such TG substrates.

  3. Integrated Tail Buffet Loads on the F/A-18

    NASA Technical Reports Server (NTRS)

    Meyn, Larry A.; James, Kevin D.

    1994-01-01

    The unsteady pressures acting on the vertical tails of a full-scale F/A-18 fighter aircraft were studied to gain a better understanding of tail-buffet loads that frequently occur on fighter aircraft operating at high angles-of-attack. Data for the study were acquired during two test entries in the 80- by 120-Foot Wind Tunnel wherein the aircraft was tested at wind speeds up to 100 knots and at angles-of-attack from 20deg to 40deg. For the purposes of this paper, the primary difference between the two tests is that, during the first wind-tunnel entry, the pressure transducers were more sparsely spaced and covered less of the fin than during the second entry. In addition to a brief description of the spectral analysis methods used for the unsteady aerodynamic pressures and loads, an analysis of the effects of sensor density on estimating integrated loads is presented. It was found that the integrated loads determined from sparse sensor arrays are significantly higher than actual loads. However, a modest increase in the number of sensors can greatly reduce the error and a method for correcting load estimates from sparse sensor arrays is also suggested. The results for the time-averaged, power-spectral analysis are then presented for the tail-fin bending moments. Power spectra are presented for the aircraft at zero sideslip over an angle-of-attack range from 20deg to 40deg and for the aircraft at an angle-of-attack of 30deg over a sideslip range from -16deg to 16deg. Since the aircraft was equipped with a removable leading-edge extension (LEX) fence to reduce tail-buffet loads, the tail-fin bending moment loads are also presented for that configuration. The LEX fence is shown to significantly reduce bending moment loads over a broad range frequencies, for all the aircraft attitudes presented.

  4. Purification and characterization of a proteinase from pineapple fruit, fruit bromelain FA2.

    PubMed

    Yamada, F; Takahashi, N; Murachi, T

    1976-06-01

    Fruit bromelain FA2, the main proteinase component of the juice of pineapple fruit, has been purified and characterized. 1. Efficient extraction of this enzyme from the crude material was possible using "Cellulosin AP," a microbial polysaccharidase preparation containing cellulase, hemicellulase, and pectinase. The enzyme was purified mainly by successive applications of anion-exchange chromatography, yielding an apparently homogeneous protein as judged by several physical, chemical, and immunochemical criteria. Properties of FA2 include: molecular weight, 31,000; isoelectric point, pH 4.6; absorbance at 280 nm of a 1% solution at pH 7.0 per cm, 19.2. 2. FA2 gave only alanine phenylthiohydantoin upon amino-terminal group analysis by the Edman procedure. Stepwise degradation yielded the amino-terminal sequence Ala-Val-Pro-Gln-Ser-Ile-Asp-Trp-Arg-Asp-Tyr-Gly-Ala. The amino acid composition of FA2 was not markedly different from that of stem bromelain, except for a much smaller lysine content and a smaller alanine content relative to glycine in FA2. FA2 contained neither amino sugars nor neutral carbohydrates as determined by several methods, so FA2 is not a glycoprotein. 3. By labeling the reactive cysteine residue (CYS) with [14C]iodoacetate, the following partial amino acid sequence has been determined. Asn-Glx-Asn-Pro-Cys-Gly-Ala-CYS.

  5. Bactrian camel nanobody-based immunoassay for specific and sensitive detection of Cry1Fa toxin.

    PubMed

    Wang, Pingyan; Li, Guanghui; Yan, Junrong; Hu, Yonghong; Zhang, Cunzheng; Liu, Xianjin; Wan, Yakun

    2014-12-15

    The variable domain of the heavy-chain-only antibody (VHH) or nanobody (Nb), derived from camelids, begins to play an important role on the detection of protein markers. In this study, we constructed a phage-displayed library of VHHs against Cry1Fa by immunizing a healthy Bactrian camel with Cry1Fa toxin. After a series of bio-panning and screening by phage display technology, three anti-Cry1Fa nanobodies (Nbs) with great difference in complementarity determining region 3 (CDR3) were obtained and they were highly specific to Cry1Fa as well as showed full of activity when exposed to 70 °C for 3 h. Through modifying Nbs with Horseradish Peroxidase (HRP) and biotin, two Nbs which can recognize the different epitopes of Cry1Fa were determined and they were used to establish a novel sandwich immune ELISA based on biotin-SA interaction for Cry1Fa detection. The immunoassay exhibited a linear range from 1 to 100 ng/mL with a detection limit of 0.88 ng/mL. The recoveries from spiked corn and soybean samples were ranged from 83.33 to 117.17%, with a coefficient of variation (C.V) less than 6.0%. All together, the proposed immunoassay will be a promising way for sensitive and accurate determination of Cry1Fa toxin. PMID:25448390

  6. FaRe: A Mathematica package for tensor reduction of Feynman integrals

    NASA Astrophysics Data System (ADS)

    Re Fiorentin, Michele

    2016-08-01

    In this paper, we present FaRe, a package for Mathematica that implements the decomposition of a generic tensor Feynman integral, with arbitrary loop number, into scalar integrals in higher dimension. In order for FaRe to work, the package FeynCalc is needed, so that the tensor structure of the different contributions is preserved and the obtained scalar integrals are grouped accordingly. FaRe can prove particularly useful when it is preferable to handle Feynman integrals with free Lorentz indices and tensor reduction of high-order integrals is needed. This can then be achieved with several powerful existing tools.

  7. Desalination of Walls and Façades

    NASA Astrophysics Data System (ADS)

    Wedekind, W.; Jáuregui Arreola, K.; Siegesmund, S.

    2012-04-01

    For large monumental objects like walls and façades, the common technique of applying poultices for desalination often are not effective. This practice is neither cost effective nor does it lead to the desired result of desalination. To manage the conservation and desalination of these kinds of objects, several sprinkling techniques are known and have been applied on historical objects. For example, in the wooden warship Vasa, which was excavated from the sea bottom in Stockholm/Sweden, a sprinkling method was applied in 1961 for conservation and desalination. A sprinkling method to desalinate porous mineral materials will be presented using three different case studies: the rock cut monument no. 825 in Petra/Jordan, the medieval monastary church of the former Franziscan convent in Zeitz/Germany and the baroque monastary church Santa Monica in Guadalajara/Mexico. Before to start with practical conservation, the material- and petropysical properties, focoussed on water transport properties, like porosity, pore size distribution, water uptake and drying rate were investigadet. Diagnostic investigations on the objects included the mapping of deterioration, moister content measurements and salt accumulation determined by borehole cuts samples at depth. In the sprinkling method water is sprayed onto the wall surface through nozzels arranged in a modular grid. Depending on the sprinkling duration, a small or a large amount of water seeps into the porous materials, whereby the depth penetration can be adjusted accordingly. The water not absorbed by the stone runs off the facade and can be collected in liter amounts and tested by electrical conductivity with respect to the dissolved substances. After the drying of the wall's surface and the accumulation of salt at the material's surface, the procedure is repeated. For each subsequent washing a lower content of salt should be brought to the surface. Step by step the salt concentration will eventually decrease to almost

  8. Insulin and AMPK regulate FA translocase/CD36 plasma membrane recruitment in cardiomyocytes via Rab GAP AS160 and Rab8a Rab GTPase.

    PubMed

    Samovski, Dmitri; Su, Xiong; Xu, Yingcheng; Abumrad, Nada A; Stahl, Philip D

    2012-04-01

    The FA translocase cluster of differentiation 36 (CD36) facilitates FA uptake by the myocardium, and its surface recruitment in cardiomyocytes is induced by insulin, AMP-dependent protein kinase (AMPK), or contraction. Dysfunction of CD36 trafficking contributes to disordered cardiac FA utilization and promotes progression to disease. The Akt substrate 160 (AS160) Rab GTPase-activating protein (GAP) is a key regulator of vesicular trafficking, and its activity is modulated via phosphorylation. Our study documents that AS160 mediates insulin or AMPK-stimulated surface translocation of CD36 in cardiomyocytes. Knock-down of AS160 redistributes CD36 to the surface and abrogates its translocation by insulin or the AMPK agonist 5-aminoimidazole-4-carboxamide-1-beta-d-ribofuranoside (AICAR). Conversely, overexpression of a phosphorylation-deficient AS160 mutant (AS160 4P) suppresses the stimulated membrane recruitment of CD36. The AS160 substrate Rab8a GTPase is shown via overexpression and knock-down studies to be specifically involved in insulin/AICAR-induced CD36 membrane recruitment. Our findings directly demonstrate AS160 regulation of CD36 trafficking. In myocytes, the AS160 pathway also mediates the effect of insulin, AMPK, or contraction on surface recruitment of the glucose transporter GLUT4. Thus, AS160 constitutes a point of convergence for coordinating physiological regulation of CD36 and GLUT4 membrane recruitment.

  9. CLUSTER CHEMISTRY

    SciTech Connect

    Muetterties, Earl L.

    1980-05-01

    Metal cluster chemistry is one of the most rapidly developing areas of inorganic and organometallic chemistry. Prior to 1960 only a few metal clusters were well characterized. However, shortly after the early development of boron cluster chemistry, the field of metal cluster chemistry began to grow at a very rapid rate and a structural and a qualitative theoretical understanding of clusters came quickly. Analyzed here is the chemistry and the general significance of clusters with particular emphasis on the cluster research within my group. The importance of coordinately unsaturated, very reactive metal clusters is the major subject of discussion.

  10. Exterior building details of Building A; north façade: fouroverfour doublehung ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Exterior building details of Building A; north façade: four-over-four double-hung wood sash window with concrete sill; southerly view - San Quentin State Prison, Building 22, Point San Quentin, San Quentin, Marin County, CA

  11. Exterior building details of Building D, west façade: second floor ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Exterior building details of Building D, west façade: second floor metal multi-pane industrial-type sash windows; easterly view - San Quentin State Prison, Building 22, Point San Quentin, San Quentin, Marin County, CA

  12. Perspective view of main entrance, north façade with two story ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Perspective view of main entrance, north façade with two story square tower, Note medical cross made of wood on tower, originally there were four. - Richmond Field Hospital, 1330 Cutting Boulevard, Richmond, Contra Costa County, CA

  13. 14. Historic American Buildings Survey, George F.A. Palmer, Photographer, 1937 ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    14. Historic American Buildings Survey, George F.A. Palmer, Photographer, 1937 VIEW OF FIREPLACE WITH BIBLICAL TILES, NORTHEAST PARLOR CHAMBER ON SECOND FLOOR-'deTERNAY'S ROOM'. - Nichols-Wanton-Hunter House, 54 Washington Street, Newport, Newport County, RI

  14. Exterior building details of Building B, east façade: ca. 1914 ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Exterior building details of Building B, east façade: ca. 1914 covered porch with an asphalt singled low-hipped roof; southwesterly view - San Quentin State Prison, Building 22, Point San Quentin, San Quentin, Marin County, CA

  15. 3. Historic American Buildings Survey, George F.A. Palmer, Photographer, June ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    3. Historic American Buildings Survey, George F.A. Palmer, Photographer, June 16, 1936 DETAIL OF HOPPER AND HOISTING MECHANISM (FOR REMOVAL OF MILL STONES. 1757, CUT IN STONE). - Benjamin Hammond Grist Mill, Hammond Hill Road, Kingston, Washington County, RI

  16. 4. Historic American Buildings Survey, George F.A. Palmer, Photographer, June ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    4. Historic American Buildings Survey, George F.A. Palmer, Photographer, June 16, 1936 DETAIL OF RECEIVING TROUGH (BASEMENT). - Benjamin Hammond Grist Mill, Hammond Hill Road, Kingston, Washington County, RI

  17. Exterior building details of Building B, east façade: second floor ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Exterior building details of Building B, east façade: second floor entrance with cement plaster profiled surround and embedded wood beam end; westerly view - San Quentin State Prison, Building 22, Point San Quentin, San Quentin, Marin County, CA

  18. NASA Videographer Captures X-51 from F/A-18 Chase

    NASA Video Gallery

    A tiny dashcam video camera records NASA Dryden videographer Lori Losey capturing the historic launch of the Air Force's X-51 Waverider hypersonic vehicle from the rear cockpit of a NASA F/A-18 flo...

  19. Exterior building details of Building D, west façade: doublehung wood ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Exterior building details of Building D, west façade: double-hung wood window with brick arch lintel and brick sill; easterly view - San Quentin State Prison, Building 22, Point San Quentin, San Quentin, Marin County, CA

  20. Exterior building details of Building E, oblique west façade: brick ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Exterior building details of Building E, oblique west façade: brick arch lintel and brick infilled window with brick sill; southeasterly view - San Quentin State Prison, Building 22, Point San Quentin, San Quentin, Marin County, CA

  1. Exterior building details of Building D, west façade: brick arch ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Exterior building details of Building D, west façade: brick arch lintel over historic entry that was brick infilled; easterly view - San Quentin State Prison, Building 22, Point San Quentin, San Quentin, Marin County, CA

  2. East and north elevations (rear façade) of quarters no. 2, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    East and north elevations (rear façade) of quarters no. 2, looking southwest. - Sacramento National Wildlife Refuge, Headquarters Complex, Quarters No. 2, 752 County Road 99W, Willows, Glenn County, CA

  3. East façade, Burton Park Club House, with Amphitheater in foreground, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    East façade, Burton Park Club House, with Amphitheater in foreground, view to north from Amphitheater stage (90 mm lens). - Burton Park, Club House & Amphitheater, Adjacent ot south end of Chestnut Avenue, San Carlos, San Mateo County, CA

  4. Portico, north façade, looking south (bearing 190). Statues of "Floral ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Portico, north façade, looking south (bearing 190). Statues of "Floral Wealth" and "Romantic Wealth" at top landing. - California State Library & Courts Building, 914 Capitol Mall, Sacramento, Sacramento County, CA

  5. Portico on south façade, looking north (bearing 350), with statues ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Portico on south façade, looking north (bearing 350), with statues of "Climatic Wealth" and "Mineral Wealth" at top landing. - California State Office Building No. 1, 915 Capitol Mall, Sacramento, Sacramento County, CA

  6. Georgia Power Co. Quantities for F.A. P. 425G (Bridge) Contract ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Georgia Power Co. Quantities for F.A. P. 425G (Bridge) Contract No. 1 and 2 - Tallulah Falls Bridge, Spanning Tallulah Falls River on U.S. Highway 23/State Route 15, Tallulah Falls, Habersham County, GA

  7. North façade of crucible steel building; looking southwest Bethlehem ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    North façade of crucible steel building; looking southwest - Bethlehem Steel Corporation, South Bethlehem Works, Crucible Steel Plant, Along Lehigh River, North of Fourth Street, West of Minsi Trail Bridge, Bethlehem, Northampton County, PA

  8. North (main) façade, looking southsoutheast (bearing 165) from steps of ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    North (main) façade, looking south-southeast (bearing 165) from steps of California State Office building (Jesse (Unruh Building). - California State Library & Courts Building, 914 Capitol Mall, Sacramento, Sacramento County, CA

  9. View southeast; detail of north façade with crane rail ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    View southeast; detail of north façade with crane rail - Naval Base Philadelphia-Philadelphia Naval Shipyard, Foundry-Propeller Shop, North of Porter Avenue, west of Third Street West, Philadelphia, Philadelphia County, PA

  10. View northeast; detail of southwest corner showing damage to façade ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    View northeast; detail of southwest corner showing damage to façade - Naval Base Philadelphia-Philadelphia Naval Shipyard, Foundry-Propeller Shop, North of Porter Avenue, west of Third Street West, Philadelphia, Philadelphia County, PA

  11. View north detail of south façade showing damage to wall ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    View north detail of south façade showing damage to wall - Naval Base Philadelphia-Philadelphia Naval Shipyard, Foundry-Propeller Shop, North of Porter Avenue, west of Third Street West, Philadelphia, Philadelphia County, PA

  12. View south; detail view of south façade at column A13 ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    View south; detail view of south façade at column A13 - Naval Base Philadelphia-Philadelphia Naval Shipyard, Foundry-Propeller Shop, North of Porter Avenue, west of Third Street West, Philadelphia, Philadelphia County, PA

  13. Exterior building details of Building A; north façade: iron latticed ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Exterior building details of Building A; north façade: iron latticed gate dungeon entrance, granite base; southerly view - San Quentin State Prison, Building 22, Point San Quentin, San Quentin, Marin County, CA

  14. NASA F/A-18 Flight-Tests Mars Science Lab Radar

    NASA Video Gallery

    A NASA F/A-18 put the Jet Propulsion Laboratory's Mars Science Laboratory landing radar to the test during recent flights over Edwards Air Force Base, Calif. With the test radar housed in a pod und...

  15. Exterior building details of Building B, east façade: ellshaped south ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Exterior building details of Building B, east façade: ell-shaped south facing concrete staircase with decorative pipe railing, second floor entrance with cement plaster profiled surround, dentil course cornice, truncated embedded wood beams, cream colored plaster-finished exterior façade, closed off window well with protruding vent; northwesterly view - San Quentin State Prison, Building 22, Point San Quentin, San Quentin, Marin County, CA

  16. Architectural Kansei of ‘Wall’ in The Façade Design by Le Corbusier

    NASA Astrophysics Data System (ADS)

    Sendai, Shoichiro

    The purpose of this paper is to discuss the modern architect Le Corbusier's architectural Kansei (sensibility) on wall in site environment through the analysis of his façade design, using Œuvres complètes (1910-1965, 8 vols., Les éditions d'architecture, Artemis, Zurich) and Le Corbusier Archives (1982-1984, 32 vols., Garland Publishing, Inc. and Fondation Le Corbusier, New York, London, Paris). At first, I arrange five façade types, according to the explanation by Le Corbusier ; ‘fenêtre en longueur (strip window)’, ‘pan de verre (glass wall)’, ‘brise-soleil (sun-breaker)’, ‘loggia’ and ‘claustra’. Through the analysis of the relationship between these types and the design process of each building, we find that Le Corbusier's façade design includes the affirmation and the negation of the ‘wall’ at the same time. In fact, the nature of façade modification during design process is divers: increase in transparency, decrease in transparency and spatialization of façade. That means, Le Corbusier studied the environmental condition by these façade types, and tried to realize the phenomenal openness. This trial bases on the function of architectural Kansei as correspondence between body and environment beyond the physical design.

  17. FANCI Regulates Recruitment of the FA Core Complex at Sites of DNA Damage Independently of FANCD2

    PubMed Central

    Castella, Maria; Jacquemont, Celine; Thompson, Elizabeth L.; Yeo, Jung Eun; Cheung, Ronald S.; Huang, Jen-Wei; Sobeck, Alexandra; Hendrickson, Eric A.; Taniguchi, Toshiyasu

    2015-01-01

    The Fanconi anemia (FA)-BRCA pathway mediates repair of DNA interstrand crosslinks. The FA core complex, a multi-subunit ubiquitin ligase, participates in the detection of DNA lesions and monoubiquitinates two downstream FA proteins, FANCD2 and FANCI (or the ID complex). However, the regulation of the FA core complex itself is poorly understood. Here we show that the FA core complex proteins are recruited to sites of DNA damage and form nuclear foci in S and G2 phases of the cell cycle. ATR kinase activity, an intact FA core complex and FANCM-FAAP24 were crucial for this recruitment. Surprisingly, FANCI, but not its partner FANCD2, was needed for efficient FA core complex foci formation. Monoubiquitination or ATR-dependent phosphorylation of FANCI were not required for the FA core complex recruitment, but FANCI deubiquitination by USP1 was. Additionally, BRCA1 was required for efficient FA core complex foci formation. These findings indicate that FANCI functions upstream of FA core complex recruitment independently of FANCD2, and alter the current view of the FA-BRCA pathway. PMID:26430909

  18. The cathepsin B inhibitor, z-FA-CMK is toxic and readily induced cell death in human T lymphocytes

    SciTech Connect

    Liow, K.Y.; Chow, S.C.

    2013-11-01

    The cathepsin B inhibitor, benzyloxycarbonyl-phenylalanine-alanine-chloromethylketone (z-FA-CMK) was found to be toxic and readily induced cell death in the human T cell line, Jurkat, whereas two other analogs benzyloxycarbonyl-phenylalanine-alanine-fluoromethylketone (z-FA-FMK) and benzyloxycarbonyl-phenylalanine-alanine-diazomethylketone (z-FA-DMK) were not toxic. The toxicity of z-FA-CMK requires not only the CMK group, but also the presence of alanine in the P1 position and the benzyloxycarbonyl group at the N-terminal. Dose–response studies showed that lower concentrations of z-FA-CMK induced apoptosis in Jurkat T cells whereas higher concentrations induced necrosis. In z-FA-CMK-induced apoptosis, both initiator caspases (-8 and -9) and effector caspases (-3, -6 and -7) were processed to their respective subunits in Jurkat T cells. However, only the pro-form of the initiator caspases were reduced in z-FA-CMK-induced necrosis and no respective subunits were apparent. The caspase inihibitor benzyloxycarbonyl-valine-alanine-aspartic acid-(O-methyl)-fluoromehylketone (z-VAD-FMK) inhibits apoptosis and caspase processing in Jurkat T cells treated with low concentration of z-FA-CMK but has no effect on z-FA-CMK-induced necrosis and the loss of initiator caspases. This suggests that the loss of initiator caspases in Jurkat T cells during z-FA-CMK-induced necrosis is not a caspase-dependent process. Taken together, we have demonstrated that z-FA-CMK is toxic to Jurkat T cells and induces apoptosis at low concentrations, while at higher concentrations the cells die of necrosis. - Highlights: • z-FA-CMK is toxic and induce cell death in the human T cells. • z-FA-CMK toxicity requires the CMK group, alanine and the benzyloxycarbonyl group. • z-FA-CMK induced apoptosis at low concentration and necrosis at high concentration.

  19. Role and mechanism of Twist1 in modulating the chemosensitivity of FaDu cells.

    PubMed

    Lu, Sumei; Yu, Liang; Mu, Yakui; Ma, Juke; Tian, Jiajun; Xu, Wei; Wang, Haibo

    2014-07-01

    Multidrug resistance (MDR) is one of the most important obstacles affecting the efficacy of chemotherapy treatments for numerous types of cancer. In the present study, we have demonstrated the possible function of Twist1 in the chemosensitivity of head and neck squamous cell carcinoma (HNSCC) and have identified that its mechanism maybe associated with MDR1/P-gp regulation. To investigate this, the hypopharyngeal cancer cell line, FaDu, and its MDR cell line induced by taxol, FaDu/T, were employed. Stable transfectants targeted to Twist1 overexpression and Twist1 silencing based on FaDu were also conducted. Morphological observation, flow cytometry, reverse transcription-polymerase chain reaction (RT-PCR), western blotting and laser scanning confocal microscope detection were utilized to detect the associations between Twist1 and the chemosensitivity of FaDu cells. Our results demonstrated that Twist1 and MDR1/P-gp were upregulated in FaDu/T cells in a MDR dose-dependent manner. The anti-apoptotic capabilities of FaDu/T cells were enhanced during MDR progression, with apoptosis-related proteins (Bcl-2, Bax, activated caspase-3 and caspase-9) changing to resist apoptosis. Twist1 overexpression decreased the sensitivity of cells to taxol as revealed by a significant increase in MDR1/P-gp and IC50 (P<0.05). This overexpression also enhanced the resistance to apoptosis, with apoptotic proteins changing to resist cell death, and inhibited Ca2+ release induced by taxol (P<0.05). Detections in Twist1 silencing cells also confirmed this result. This study provided evidence that alterations of Twist1 expression modulates the chemosensitivity of FaDu cells to taxol. Therefore, Twist1 knockdown may be a promising treatment regimen for advanced hypopharyngeal carcinoma patients with MDR.

  20. Berberine-induced anticancer activities in FaDu head and neck squamous cell carcinoma cells.

    PubMed

    Seo, Yo-Seob; Yim, Min-Ji; Kim, Bok-Hee; Kang, Kyung-Rok; Lee, Sook-Young; Oh, Ji-Su; You, Jae-Seek; Kim, Su-Gwan; Yu, Sang-Joun; Lee, Gyeong-Je; Kim, Do Kyung; Kim, Chun Sung; Kim, Jin-Soo; Kim, Jae-Sung

    2015-12-01

    In the present study, we investigated berberine‑induced apoptosis and the signaling pathways underlying its activity in FaDu head and neck squamous cell carcinoma cells. Berberine did not affect the viability of primary human normal oral keratinocytes. In contrast, the cytotoxicity of berberine was significantly increased in FaDu cells stimulated with berberine for 24 h. Furthermore, berberine increased nuclear condensation and apoptosis rates in FaDu cells than those in untreated control cells. Berberine also induced the upregulation of apoptotic ligands, such as FasL and TNF-related apoptosis-inducing ligand, and triggered the activation of caspase-8, -7 and -3, and poly(ADP ribose) polymerase, characteristic of death receptor-dependent extrinsic apoptosis. Moreover, berberine activated the mitochondria‑dependent apoptotic signaling pathway by upregulating pro-apoptotic factors, such as Bax, Bad, Apaf-1, and the active form of caspase-9, and downregulating anti-apoptotic factors, such as Bcl-2 and Bcl-xL. In addition, berberine increased the expression of the tumor suppressor p53 in FaDu cells. The pan-caspase inhibitor Z-VAD-fmk suppressed the activation of caspase-3 and prevented cytotoxicity in FaDu cells treated with berberine. Interestingly, berberine suppressed cell migration through downregulation of vascular endothelial growth factor (VEGF), matrix metalloproteinase (MMP)-2, and MMP-9. Moreover, the phosphorylation of extracellular signal-regulated kinase (ERK1/2) and p38, components of the mitogen-activated protein kinase pathway that are associated with the expression of MMP and VEGF, was suppressed in FaDu cells treated with berberine for 24 h. Therefore, these data suggested that berberine exerted anticancer effects in FaDu cells through induction of apoptosis and suppression of migration. Berberine may have potential applications as a chemotherapeutic agent for the management of head and neck squamous carcinoma.

  1. Both FA- and mPEG-conjugated chitosan nanoparticles for targeted cellular uptake and enhanced tumor tissue distribution

    NASA Astrophysics Data System (ADS)

    Hou, Zhenqing; Zhan, Chuanming; Jiang, Qiwei; Hu, Quan; Li, Le; Chang, Di; Yang, Xiangrui; Wang, Yixiao; Li, Yang; Ye, Shefang; Xie, Liya; Yi, Yunfeng; Zhang, Qiqing

    2011-10-01

    Both folic acid (FA)- and methoxypoly(ethylene glycol) (mPEG)-conjugated chitosan nanoparticles (NPs) had been designed for targeted and prolong anticancer drug delivery system. The chitosan NPs were prepared with combination of ionic gelation and chemical cross-linking method, followed by conjugation with both FA and mPEG, respectively. FA-mPEG-NPs were compared with either NPs or mPEG-/FA-NPs in terms of their size, targeting cellular efficiency and tumor tissue distribution. The specificity of the mPEG-FA-NPs targeting cancerous cells was demonstrated by comparative intracellular uptake of NPs and mPEG-/FA-NPs by human adenocarcinoma HeLa cells. Mitomycin C (MMC), as a model drug, was loaded to the mPEG-FA-NPs. Results show that the chitosan NPs presented a narrow-size distribution with an average diameter about 200 nm regardless of the type of functional group. In addition, MMC was easily loaded to the mPEG-FA-NPs with drug-loading content of 9.1%, and the drug releases were biphasic with an initial burst release, followed by a subsequent slower release. Laser confocal scanning imaging proved that both mPEG-FA-NPs and FA-NPs could greatly enhance uptake by HeLa cells. In vivo animal experiments, using a nude mice xenograft model, demonstrated that an increased amount of mPEG-FA-NPs or FA-NPs were accumulated in the tumor tissue relative to the mPEG-NPs or NPs alone. These results suggest that both FA- and mPEG-conjugated chitosan NPs are potentially prolonged drug delivery system for tumor cell-selective targeting treatments.

  2. Analysis and Assessment of Strength Development in Compressed FaL-G Blocks

    NASA Astrophysics Data System (ADS)

    Nagendra Prasad, K.; Vijaya Bhaskar, S.; Narasimhulu, M. L.; Manohara Reddy, R.

    2014-09-01

    Of the several options explored in large scale utilization of fly ash, such as production of blended cements, high volume fly ash cement concretes, fly ash, lime and gypsum (FaL-G) combinations, alkali activated fly ash mortars and concretes are of recent innovations. The last two are non-traditional cementing materials, since no cement is used in processing of these materials. This investigation deals with analysis and assessment of strength development in compressed FaL-G blocks. FaL-G chemistry provides a strong scientific base for understanding the mechanisms of interaction. But an equally strong technological base in the production of FaL-G blocks is the need of the hour. In this investigation, analysis has been made to advance a phenomenological model to arrive at the combinations of the ingredients to produce compressed blocks to meet the strength development desired at specified age, based on carefully planned experimental data generated. The analysis of test results has been done within the framework of Abrams' law, which is extensively used in concrete technology. The validity has been examined with an independent set of experimental data. With incorporation of more data covering still wider spectrum of materials the phenomenological model can further be reinforced as a viable tool in the production of compressed FaL-G blocks.

  3. Pulsed electron paramagnetic resonance experiments identify the paramagnetic intermediates in the pyruvate ferredoxin oxidoreductase catalytic cycle.

    PubMed

    Astashkin, Andrei V; Seravalli, Javier; Mansoorabadi, Steven O; Reed, George H; Ragsdale, Stephen W

    2006-03-29

    Pyruvate ferredoxin oxidoreductase (PFOR) is central to the anaerobic metabolism of many bacteria and amitochondriate eukaryotes. PFOR contains thiamine pyrophosphate (TPP) and three [4Fe-4S] clusters, which link pyruvate oxidation to reduction of ferredoxin. In the PFOR reaction, TPP reacts with pyruvate to form lactyl-TPP, which undergoes decarboxylation to form a hydroxyethyl-TPP (HE-TPP) intermediate. One electron is then transferred from HE-TPP to one of the three [4Fe-4S] clusters to form an HE-TPP radical and a [4Fe-4S]1+ intermediate. Pulsed EPR methods have been used to measure the distance between the HE-TPP radical and the [4Fe-4S]1+ cluster to which it is coupled. Computational analysis including the PFOR crystal structure and the spin distribution in the HE-TPP radical and in the reduced [4Fe-4S] cluster demonstrates that the distance between the HE-TPP radical and the medial cluster B matches the experimentally determined dipolar interaction, while one of the other two clusters is too close and the other is too far away. These results clearly demonstrate that it is the medial cluster (cluster B) that is reduced. Thus, rapid electron transfer occurs through the electron-transfer chain, which leaves an oxidized proximal cluster poised to accept an electron from the HE-TPP radical in the subsequent reaction step. PMID:16551078

  4. Cluster headache

    MedlinePlus

    Histamine headache; Headache - histamine; Migrainous neuralgia; Headache - cluster; Horton's headache; Vascular headache - cluster ... be related to the body's sudden release of histamine (chemical in the body released during an allergic ...

  5. Flight Tests of a Ministick Controller in an F/A-18 Airplane

    NASA Technical Reports Server (NTRS)

    Stoliker, Patrick C.; Carter, John

    2003-01-01

    In March of 1999, five pilots performed flight tests to evaluate the handling qualities of an F/A-18 research airplane equipped with a small-displacement center stick (ministick) controller that had been developed for the JAS 39 Gripen airplane (a fighter/attack/ reconnaissance airplane used by the Swedish air force). For these tests, the ministick was installed in the aft cockpit (see figure) and production support flight control computers (PSFCCs) were used as interfaces between the controller hardware and the standard F/A-18 flight-control laws. The primary objective of the flight tests was to assess any changes in handling qualities of the F/A-18 airplane attributable to the mechanical characteristics of the ministick. The secondary objective was to demonstrate the capability of the PSFCCs to support flight-test experiments.

  6. Aerodynamics of powered missile separation from F/A-18 aircraft

    NASA Technical Reports Server (NTRS)

    Ahmad, J. U.; Shanks, S. P.; Buning, P. G.

    1993-01-01

    A 3D dynamic 'chimera' algorithm that solves the thin-layer Navier-Stokes equations over multiple moving bodies was modified to numerically simulate the aerodynamics, missile dynamics, and missile plume interactions of a missile separating from a generic wing and from an F/A-18 aircraft in transonic flow. The missile is mounted below the wing for missile separation from the wing and on the F/A-18 fuselage at the engine inlet side for missile separation from aircraft. Static and powered missile separation cases are considered to examine the influence of the missile and plume on the wing and F/A-18 fuselage and engine inlet. The aircraft and missile are at two degrees angle of attack, Reynolds number of 10 million, freestream Mach number of 1.05 and plume Mach number of 3.0. The computational results show the details of the flow field.

  7. Spin distribution of the H-cluster in the H(ox)-CO state of the [FeFe] hydrogenase from Desulfovibrio desulfuricans: HYSCORE and ENDOR study of (14)N and (13)C nuclear interactions.

    PubMed

    Silakov, Alexey; Wenk, Brian; Reijerse, Eduard; Albracht, Simon P J; Lubitz, Wolfgang

    2009-02-01

    Hydrogenases are enzymes which catalyze the reversible cleavage of molecular hydrogen into protons and electrons. In [FeFe] hydrogenases the active center is a 6Fe6S cluster, referred to as the "H-cluster." It consists of the redox-active binuclear subcluster ([2Fe](H)) coordinated by CN(-) and CO ligands and the cubane-like [4Fe-4S](H) subcluster which is connected to the protein via Cys ligands. One of these Cys ligands bridges to the [2Fe](H) subcluster. The CO-inhibited form of [FeFe] hydrogenase isolated from Desulfovibrio desulfuricans was studied using advanced EPR methods. In the H(ox)-CO state the open coordination site at the [2Fe](H) subcluster is blocked by extrinsic CO, giving rise to an EPR-active S = 1/2 species. The CO inhibited state was prepared with (13)CO and illuminated under white light at 273 K. In this case scrambling of the CO ligands occurs. Three (13)C hyperfine couplings of 17.1, 7.4, and 3.8 MHz (isotropic part) were observed and assigned to (13)CO at the extrinsic, the bridging, and the terminal CO-ligand positions of the distal iron, respectively. No (13)CO exchange of the CO ligand to the proximal iron was observed. The hyperfine interactions detected indicate a rather large distribution of the spin density over the terminal and bridging CO ligands attached to the distal iron. Furthermore, (14)N nuclear spin interactions were measured. On the basis of the observed (14)N hyperfine couplings, which result from the CN(-) ligands of the [2Fe](H) subcluster, it has been concluded that there is very little unpaired spin density on the cyanides of the binuclear subcluster.

  8. Meaningful Clusters

    SciTech Connect

    Sanfilippo, Antonio P.; Calapristi, Augustin J.; Crow, Vernon L.; Hetzler, Elizabeth G.; Turner, Alan E.

    2004-05-26

    We present an approach to the disambiguation of cluster labels that capitalizes on the notion of semantic similarity to assign WordNet senses to cluster labels. The approach provides interesting insights on how document clustering can provide the basis for developing a novel approach to word sense disambiguation.

  9. Abell Clusters

    NASA Astrophysics Data System (ADS)

    Katgert, P.; Murdin, P.

    2000-11-01

    Abell clusters are the most conspicuous groupings of galaxies identified by George Abell on the plates of the first photographic survey made with the SCHMIDT TELESCOPE at Mount Palomar in the 1950s. Sometimes, the term Abell clusters is used as a synonym of nearby, optically selected galaxy clusters....

  10. Birth order and avuncular tendencies in Samoan men and fa'afafine.

    PubMed

    Vanderlaan, Doug P; Vasey, Paul L

    2013-04-01

    Androphilia refers to sexual attraction and arousal to males whereas gynephilia refers to sexual attraction and arousal to females. In Samoa, transgendered androphilic males are known locally as fa'afafine. Previous research has shown that, compared to Samoan gynephilic men, fa'afafine report greater willingness to invest time and money toward nieces and nephews (i.e., greater avuncular tendencies) and also have greater numbers of older brothers and older sisters. The present study examined whether the Samoan male sexual orientation difference in avuncular tendencies could be accounted for by these parallel differences in numbers of older brothers and older sisters. The sample included 204 fa'afafine and 272 Samoan gynephilic men from our Samoan data archive for whom we had concurrent information on (1) a measure of willingness to invest time and money in nieces and nephews (i.e., avuncular tendencies) and (2) numbers of older and younger biological brothers and sisters. Among fa'afafine, but not Samoan gynephilic men, number of older brothers and number of older sisters were both significantly positively associated with avuncular tendencies. When controlling for number of older brothers, the magnitude of the male sexual orientation difference in avuncular tendencies was lowered, but remained statistically significant. In contrast, when controlling for number of older sisters, the male sexual orientation difference in avuncular tendencies ceased to exist. Discussion detailed how these findings help hone in on the proximate basis of elevated avuncular tendencies among fa'afafine. In addition, discussion focused on how particular evolutionary and cultural factors might relate to the avuncularity of fa'afafine.

  11. Detecting blind building façades from highly overlapping wide angle aerial imagery

    NASA Astrophysics Data System (ADS)

    Burochin, Jean-Pascal; Vallet, Bruno; Brédif, Mathieu; Mallet, Clément; Brosset, Thomas; Paparoditis, Nicolas

    2014-10-01

    This paper deals with the identification of blind building façades, i.e. façades which have no openings, in wide angle aerial images with a decimeter pixel size, acquired by nadir looking cameras. This blindness characterization is in general crucial for real estate estimation and has, at least in France, a particular importance on the evaluation of legal permission of constructing on a parcel due to local urban planning schemes. We assume that we have at our disposal an aerial survey with a relatively high stereo overlap along-track and across-track and a 3D city model of LoD 1, that can have been generated with the input images. The 3D model is textured with the aerial imagery by taking into account the 3D occlusions and by selecting for each façade the best available resolution texture seeing the whole façade. We then parse all 3D façades textures by looking for evidence of openings (windows or doors). This evidence is characterized by a comprehensive set of basic radiometric and geometrical features. The blindness prognostic is then elaborated through an (SVM) supervised classification. Despite the relatively low resolution of the images, we reach a classification accuracy of around 85% on decimeter resolution imagery with 60 × 40 % stereo overlap. On the one hand, we show that the results are very sensitive to the texturing resampling process and to vegetation presence on façade textures. On the other hand, the most relevant features for our classification framework are related to texture uniformity and horizontal aspect and to the maximal contrast of the opening detections. We conclude that standard aerial imagery used to build 3D city models can also be exploited to some extent and at no additional cost for facade blindness characterisation.

  12. A Security-façade Library for Virtual-observatory Software

    NASA Astrophysics Data System (ADS)

    Rixon, G.

    2009-09-01

    The security-façade library implements, for Java, IVOA's security standards. It supports the authentication mechanisms for SOAP and REST web-services, the sign-on mechanisms (with MyProxy, AstroGrid Accounts protocol or local credential-caches), the delegation protocol, and RFC3820-enabled HTTPS for Apache Tomcat. Using the façade, a developer who is not a security specialist can easily add access control to a virtual-observatory service and call secured services from an application. The library has been an internal part of AstroGrid software for some time and it is now offered for use by other developers.

  13. Genetic analysis of strawberry fruit aroma and identification of O-methyltransferase FaOMT as the locus controlling natural variation in mesifurane content.

    PubMed

    Zorrilla-Fontanesi, Yasmín; Rambla, José-Luis; Cabeza, Amalia; Medina, Juan J; Sánchez-Sevilla, José F; Valpuesta, Victoriano; Botella, Miguel A; Granell, Antonio; Amaya, Iraida

    2012-06-01

    Improvement of strawberry (Fragaria × ananassa) fruit flavor is an important goal in breeding programs. To investigate genetic factors controlling this complex trait, a strawberry mapping population derived from genotype '1392', selected for its superior flavor, and '232' was profiled for volatile compounds over 4 years by headspace solid phase microextraction coupled to gas chromatography and mass spectrometry. More than 300 volatile compounds were detected, of which 87 were identified by comparison of mass spectrum and retention time to those of pure standards. Parental line '1392' displayed higher volatile levels than '232', and these and many other compounds with similar levels in both parents segregated in the progeny. Cluster analysis grouped the volatiles into distinct chemically related families and revealed a complex metabolic network underlying volatile production in strawberry fruit. Quantitative trait loci (QTL) detection was carried out over 3 years based on a double pseudo-testcross strategy. Seventy QTLs covering 48 different volatiles were detected, with several of them being stable over time and mapped as major QTLs. Loci controlling γ-decalactone and mesifurane content were mapped as qualitative traits. Using a candidate gene approach we have assigned genes that are likely responsible for several of the QTLs. As a proof of concept we show that one homoeolog of the O-methyltransferase gene (FaOMT) is the locus responsible for the natural variation of mesifurane content. Sequence analysis identified 30 bp in the promoter of this FaOMT homoeolog containing putative binding sites for basic/helix-loop-helix, MYB, and BZIP transcription factors. This polymorphism fully cosegregates with both the presence of mesifurane and the high expression of FaOMT during ripening.

  14. Exterior building details of Building A; north façade: two threelight ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Exterior building details of Building A; north façade: two three-light wood casement windows flank a three-light fixed wood window with concrete sill; southerly view - San Quentin State Prison, Building 22, Point San Quentin, San Quentin, Marin County, CA

  15. HEAT TRANSFER EVALUATION OF HFC-236FA IN CONDENSATION AND EVAPORATION

    EPA Science Inventory

    The report gives results of an evaluation of the shell-side heat transfer performance of hydrofluorocarbon (HFC)-236fa, which is considered to be a potential substitute for chlorofluorocarbon (CFC)-114 in Navy shipboard chillers, for both conventional finned [1024- and 1575-fpm (...

  16. MISCIBILITY, SOLUBILITY, VISCOSITY, AND DENSITY MEASUREMENTS FOR R-236FA WITH POTENTIAL LUBRICANTS

    EPA Science Inventory

    The report gives results of miscibility, solubility, viscosity, and density measurements for refrigerant R-236fa and two potential lubricants . (The data are needed to determine the suitability of refrigerant/lubricant combinations for use in refrigeration systems.) The tested oi...

  17. Exterior building details of Building A; east façade: profiled cement ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Exterior building details of Building A; east façade: profiled cement plaster door surround, black mesh gate protects a two-light transom atop non-original metal door; westerly view - San Quentin State Prison, Building 22, Point San Quentin, San Quentin, Marin County, CA

  18. Automatic modelling of building façade objects via primitive shapes

    NASA Astrophysics Data System (ADS)

    Hetti Arachchige, N.; Perera, S.

    2014-08-01

    This paper presents a new approach to recognize individual façade objects and to reconstruct such objects in 3D using MLS point clouds. Core of the approach is a primitive shape based algorithm, which introduces building primitives, to identify the façade objects separately from other irrelevant objects and then to model the correct topology. The primitive shape is identified against defined different primitive shapes by using the Douglas-Peucker algorithm. The advantage of this process is that it offers an ability not only to model correct geometric shapes but also to remove occlusion effects from the final model. To evaluate the validity of the proposed approach, experiments have been conducted using two types of street scene point clouds captured by Optech Lynx Mobile Mapper System and Z+F laser scanner. Results of the experiments show that the completeness, correctness, and quality of the reconstructed building façade objects are well over 90 %, proving the proposed method is a promising solution for modelling 3D façade objects with different geometric shapes.

  19. Missionaries and Tonic Sol-fa Music Pedagogy in 19th-Century China

    ERIC Educational Resources Information Center

    Southcott, Jane E.; Lee, Angela Hao-Chun

    2008-01-01

    In the 19th century, Christian missionaries in China, as elsewhere, used the Tonic Sol-fa method of music instruction to aid their evangelizing. This system was designed to improve congregational singing in churches, Sunday schools and missions. The London Missionary Society and other evangelical groups employed the method. These missionaries took…

  20. Exterior building details of Building A; east façade: recessed panel ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Exterior building details of Building A; east façade: recessed panel inscribed "1859", historic window opening with concrete sill above door, cement plaster dentil course and cornice, truncated wood beam ends, plaster finished brick wall, granite base; westerly view - San Quentin State Prison, Building 22, Point San Quentin, San Quentin, Marin County, CA

  1. Exterior building details of Building A; east façade: concrete staircase, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Exterior building details of Building A; east façade: concrete staircase, profiled cement, plaster door surround, recessed panel inscribed "1859", historic window opening with concrete sill above door, cement plaster dentil course and cornice truncated wood beam ends, plaster finished brick wall, granite base; westerly view - San Quentin State Prison, Building 22, Point San Quentin, San Quentin, Marin County, CA

  2. NEW CHEMICAL ALTERNATIVE FOR OZONE-DEPLETING SUBSTANCES: HFC-236FA

    EPA Science Inventory

    The report gives results of a preliminary evaluation of a new hydrofluorocarbon (HFC)--HFC-236fa or 1,1,1,3,3,3-hexafluoropropane--as a possible alternative for chlorofluorocarbon (CFC)-114 (1,2-dichloro-1,1,2,2-tetrafluoroethane) refrigerant for chillers and as a possible fire s...

  3. Exterior building details of Building C, south façade: second floor" ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Exterior building details of Building C, south façade: second floor" four-over-four windows, arch brick lintels, brick sills, decorative metal grilles and tiebacks; northwesterly view - San Quentin State Prison, Building 22, Point San Quentin, San Quentin, Marin County, CA

  4. Exterior building details of Building B, west façade: road level ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Exterior building details of Building B, west façade: road level four-over-four double-hung painted-wood windows with brick sill and arch brick lintels; easterly view - San Quentin State Prison, Building 22, Point San Quentin, San Quentin, Marin County, CA

  5. Exterior building details of Building C, east façade: historic fouroverfour ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Exterior building details of Building C, east façade: historic four-over-four window, brick lintel, brick quoins, corbelled brick cornice, spiral metal staircase to inclined stairs rising to second floor cantilever wooden walkway; westerly view - San Quentin State Prison, Building 22, Point San Quentin, San Quentin, Marin County, CA

  6. Exterior building details of Building C, west façade: second floor: ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Exterior building details of Building C, west façade: second floor: four-over-four windows, arch brick lintels, brick sills, decorative metal grilles; easterly view - San Quentin State Prison, Building 22, Point San Quentin, San Quentin, Marin County, CA

  7. Exterior building details of Building C, east façade: inscribed date ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Exterior building details of Building C, east façade: inscribed date panel "hospital 1885", corbelled brick belt course, parapet, second floor historic four-over-four window with brick lintels, quoins and decorative metal grilled, cantilever wooden walkway; westerly view - San Quentin State Prison, Building 22, Point San Quentin, San Quentin, Marin County, CA

  8. Exterior building details of Building A; west façade: exposed common ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Exterior building details of Building A; west façade: exposed common bond brick wall, arched brick lintels over a two single-light casement window with brick sills, arched brick lintel over door cornice; easterly view - San Quentin State Prison, Building 22, Point San Quentin, San Quentin, Marin County, CA

  9. Exterior building details of Building B, west façade: two paintedwood ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Exterior building details of Building B, west façade: two painted-wood single-light casements over two-light casements with concrete sill and arch brick lintel, over infilled brick patch with arch brick lintel, brick lintel above windows and brick infilled oval; easterly view - San Quentin State Prison, Building 22, Point San Quentin, San Quentin, Marin County, CA

  10. Exterior building details of Building C, east façade: brick quoins, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Exterior building details of Building C, east façade: brick quoins, brick lintels, brick window sills, decorative metal grilles, scored cement finished brick wall; westerly view - San Quentin State Prison, Building 22, Point San Quentin, San Quentin, Marin County, CA

  11. 75 FR 27489 - Airworthiness Directives; Pratt & Whitney Canada Corp. PW615F-A Turbofan Engines

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-05-17

    .... Investigation showed that the Fuel Filter Bypass Valve poppet in the Fuel Oil Heat Exchanger (FOHE) on that.... PW615F-A turbofan engines with fuel/oil heat exchanger (FOHE) part number (P/ N) 35C3778-01 or P/N... Federal holidays. Fax: (202) 493-2251. Contact Pratt & Whitney Canada Corp., 1000...

  12. Exterior building details of Building A; east façade: fixed fiveoverfive ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Exterior building details of Building A; east façade: fixed five-over-five wood windows with five-light hoppers with concrete sills; westerly view - San Quentin State Prison, Building 22, Point San Quentin, San Quentin, Marin County, CA

  13. Genome Sequence of the Alkaline-Tolerant Cellulomonas sp. Strain FA1

    DOE PAGES

    Cohen, Michael F.; Hu, Ping; Nguyen, My Vu; Kamennaya, Nina; Brown, Natasha; Woyke, Tanja; Kyrpides, Nikos; Holman, Hoi-Ying; Torok, Tamas

    2015-06-18

    We present the genome of the cellulose-degrading Cellulomonas sp. strain FA1 isolated from an actively serpentinizing highly alkaline spring. Knowledge of this genome will enable studies into the molecular basis of plant material degradation in alkaline environments and inform the development of lignocellulose bioprocessing procedures for biofuel production.

  14. Genome Sequence of the Alkaline-Tolerant Cellulomonas sp. Strain FA1

    SciTech Connect

    Cohen, Michael F.; Hu, Ping; Nguyen, My Vu; Kamennaya, Nina; Brown, Natasha; Woyke, Tanja; Kyrpides, Nikos; Holman, Hoi-Ying; Torok, Tamas

    2015-06-18

    We present the genome of the cellulose-degrading Cellulomonas sp. strain FA1 isolated from an actively serpentinizing highly alkaline spring. Knowledge of this genome will enable studies into the molecular basis of plant material degradation in alkaline environments and inform the development of lignocellulose bioprocessing procedures for biofuel production.

  15. Leaching of biocides from façades under natural weather conditions.

    PubMed

    Burkhardt, M; Zuleeg, S; Vonbank, R; Bester, K; Carmeliet, J; Boller, M; Wangler, T

    2012-05-15

    Biocides are included in organic building façade coatings as protection against biological attack by algae and fungi but have the potential to enter the environment via leaching into runoff from wind driven rain. The following field study correlates wind driven rain to runoff and measured the release of several commonly used organic biocides (terbutryn, Irgarol 1051, diuron, isoproturon, OIT, DCOIT) in organic façade coatings from four coating systems. During one year of exposure of a west oriented model house façade in the Zurich, Switzerland area, an average of 62.7 L/m(2), or 6.3% of annual precipitation came off the four façade panels installed as runoff. The ISO method for calculating wind driven rain loads is adapted to predict runoff and can be used in the calculation of emissions in the field. Biocide concentrations tend to be higher in the early lifetime of the coatings and then reach fairly consistent levels later, generally ranging on the order of mg/L or hundreds of μg/L. On the basis of the amount remaining in the film after exposure, the occurrence of transformation products, and the calculated amounts in the leachate, degradation plays a significant role in the overall mass balance.

  16. Exterior building details of Building C, east façade: historic six ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Exterior building details of Building C, east façade: historic six light entry double door with three light transom, historic six light door with a one light transom, arch brick lintels and quoins, scored cement plaster finished brick walls; westerly view - San Quentin State Prison, Building 22, Point San Quentin, San Quentin, Marin County, CA

  17. Consumption of fa cai Nostoc soup: a potential for BMAA exposure from Nostoc cyanobacteria in China?

    PubMed

    Roney, Britton R; Renhui, Li; Banack, Sandra Anne; Murch, Susan; Honegger, Rosmarie; Cox, Paul Alan

    2009-01-01

    Grown in arid regions of western China the cyanobacterium Nostoc flagelliforme--called fa cai in Mandarin and fat choy in Cantonese--is wild-harvested and used to make soup consumed during New Year's celebrations. High prices, up to $125 USD/kg, led to overharvesting in Inner Mongolia, Ningxia, Gansu, Qinghai, and Xinjiang. Degradation of arid ecosystems, desertification, and conflicts between Nostoc harvesters and Mongol herdsmen concerned the Chinese environmental authorities, leading to a government ban of Nostoc commerce. This ban stimulated increased marketing of a substitute made from starch. We analysed samples purchased throughout China as well as in Chinese markets in the United States and the United Kingdom. Some were counterfeits consisting of dyed starch noodles. A few samples from California contained Nostoc flagelliforme but were adulterated with starch noodles. Other samples, including those from the United Kingdom, consisted of pure Nostoc flagelliforme. A recent survey of markets in Cheng Du showed no real Nostoc flagelliforme to be marketed. Real and artificial fa cai differ in the presence of beta-N-methylamino-L-alanine (BMAA). Given its status as a high-priced luxury food, the government ban on collection and marketing, and the replacement of real fa cai with starch substitutes consumed only on special occasions, it is anticipated that dietary exposure to BMAA from fa cai will be reduced in the future in China.

  18. South façade, view to north from center of Elk Grove ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    South façade, view to north from center of Elk Grove Boulevard. Drew-Sherwood Tank House. (HABS No. CA-2610-B) visible at left of house. - Drew-Sherwood Farm, House, 7927 Elk Grove Boulevard, Elk Grove, Sacramento County, CA

  19. View of rear façade of office building; note projecting bay, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    View of rear façade of office building; note projecting bay, above the basement level, which commanded a view of the iron works - Everett Iron Company, Office Building, 0.25 mile Southwest of Everett, Earlston, Bedford County, PA

  20. Genome Sequence of the Alkaline-Tolerant Cellulomonas sp. Strain FA1.

    PubMed

    Cohen, Michael F; Hu, Ping; Nguyen, My Vu; Kamennaya, Nina; Brown, Natasha; Woyke, Tanja; Kyrpides, Nikos; Holman, Hoi-Ying; Torok, Tamas

    2015-06-18

    We present the genome of the cellulose-degrading Cellulomonas sp. strain FA1 isolated from an actively serpentinizing highly alkaline spring. Knowledge of this genome will enable studies into the molecular basis of plant material degradation in alkaline environments and inform the development of lignocellulose bioprocessing procedures for biofuel production.

  1. Genome Sequence of the Alkaline-Tolerant Cellulomonas sp. Strain FA1

    PubMed Central

    Hu, Ping; Nguyen, My Vu; Kamennaya, Nina; Brown, Natasha; Woyke, Tanja; Kyrpides, Nikos; Holman, Hoi-Ying; Torok, Tamas

    2015-01-01

    We present the genome of the cellulose-degrading Cellulomonas sp. strain FA1 isolated from an actively serpentinizing highly alkaline spring. Knowledge of this genome will enable studies into the molecular basis of plant material degradation in alkaline environments and inform the development of lignocellulose bioprocessing procedures for biofuel production. PMID:26089422

  2. Data Clustering

    NASA Astrophysics Data System (ADS)

    Wagstaff, Kiri L.

    2012-03-01

    On obtaining a new data set, the researcher is immediately faced with the challenge of obtaining a high-level understanding from the observations. What does a typical item look like? What are the dominant trends? How many distinct groups are included in the data set, and how is each one characterized? Which observable values are common, and which rarely occur? Which items stand out as anomalies or outliers from the rest of the data? This challenge is exacerbated by the steady growth in data set size [11] as new instruments push into new frontiers of parameter space, via improvements in temporal, spatial, and spectral resolution, or by the desire to "fuse" observations from different modalities and instruments into a larger-picture understanding of the same underlying phenomenon. Data clustering algorithms provide a variety of solutions for this task. They can generate summaries, locate outliers, compress data, identify dense or sparse regions of feature space, and build data models. It is useful to note up front that "clusters" in this context refer to groups of items within some descriptive feature space, not (necessarily) to "galaxy clusters" which are dense regions in physical space. The goal of this chapter is to survey a variety of data clustering methods, with an eye toward their applicability to astronomical data analysis. In addition to improving the individual researcher’s understanding of a given data set, clustering has led directly to scientific advances, such as the discovery of new subclasses of stars [14] and gamma-ray bursts (GRBs) [38]. All clustering algorithms seek to identify groups within a data set that reflect some observed, quantifiable structure. Clustering is traditionally an unsupervised approach to data analysis, in the sense that it operates without any direct guidance about which items should be assigned to which clusters. There has been a recent trend in the clustering literature toward supporting semisupervised or constrained

  3. Cat allergen sampling by a new personal collector (Partrap FA 52).

    PubMed

    Liccardi, G; Russo, M; Barber, D; Califano, C; Parmiani, S; D'Amato, M; D'Amato, G

    2000-01-01

    Recent studies carried out by us and others have demonstrated that Fel d 1, the main cat allergen, may be passively transferred by human clothing in cat-free environments. Consequently, the monitoring of the Fel d 1 levels either in indoor environments or on allergen-contaminated clothes of sensitized cat owners should be considered an important tool in prevention strategies. The aim of this study was to evaluate the efficacy of a personal air sampler (Partrap FA 52) in capturing cat allergen from wool fabrics. Seven identical wool webs (80 x 100 cm) were put in the baskets of seven male cats for 1 week. In our laboratory each web was divided into two parts (80 x 50 cm), the first of which was then divided in two parts (40 x 50 cm) and each was vacuumed directly by one collector. The second part was dry-cleaned at a professional cleaners, divided in two parts and then vacuumed. For the dust collection from wool webs we used a fixed high volume air sampler (CF/20 Gelaire Flow Labs, Milan, Italy) and a personal collector (Partrap FA 52, Coppa Biella, Italy). Fel d 1 content was determined using a two site ELISA (ALK-Abelló Group, Madrid, Spain). Both air samplers collected cat allergens from cat-exposed wool fabrics before and after dry cleaning. There were significant differences between the levels of Fel d 1 before and after dry cleaning by using either CF/20 or Partrap FA52 and between the levels of Fel d 1 before dry cleaning using CF/20 and Partrap FA 52. The results of our study suggest that Partrap FA 52, although its air flow is half that of the CF/20, is able to collect even residual amounts of cat allergen from wool webs after dry cleaning and consequently may constitute a simple and effective means of monitoring the levels of Fel d 1 on the clothes of cat owners.

  4. Slicing Method for curved façade and window extraction from point clouds

    NASA Astrophysics Data System (ADS)

    Iman Zolanvari, S. M.; Laefer, Debra F.

    2016-09-01

    Laser scanning technology is a fast and reliable method to survey structures. However, the automatic conversion of such data into solid models for computation remains a major challenge, especially where non-rectilinear features are present. Since, openings and the overall dimensions of the buildings are the most critical elements in computational models for structural analysis, this article introduces the Slicing Method as a new, computationally-efficient method for extracting overall façade and window boundary points for reconstructing a façade into a geometry compatible for computational modelling. After finding a principal plane, the technique slices a façade into limited portions, with each slice representing a unique, imaginary section passing through a building. This is done along a façade's principal axes to segregate window and door openings from structural portions of the load-bearing masonry walls. The method detects each opening area's boundaries, as well as the overall boundary of the façade, in part, by using a one-dimensional projection to accelerate processing. Slices were optimised as 14.3 slices per vertical metre of building and 25 slices per horizontal metre of building, irrespective of building configuration or complexity. The proposed procedure was validated by its application to three highly decorative, historic brick buildings. Accuracy in excess of 93% was achieved with no manual intervention on highly complex buildings and nearly 100% on simple ones. Furthermore, computational times were less than 3 sec for data sets up to 2.6 million points, while similar existing approaches required more than 16 hr for such datasets.

  5. A case report and literature review of Fanconi Anemia (FA) diagnosed by genetic testing.

    PubMed

    Solomon, Ponnumony John; Margaret, Priya; Rajendran, Ramya; Ramalingam, Revathy; Menezes, Godfred A; Shirley, Alph S; Lee, Seung Jun; Seong, Moon-Woo; Park, Sung Sup; Seol, Dodam; Seo, Soo Hyun

    2015-01-01

    Fanconi anemia (FA) is a genetically heterogeneous rare autosomal recessive disorder characterized by congenital malformations, hematological problems and predisposition to malignancies. The genes that have been found to be mutated in FA patients are called FANC. To date 16 distinct FANC genes have been reported. Among these, mutations in FANCA are the most frequent among FA patients worldwide which account for 60- 65%. In this study, a nine years old male child was brought to our hospital one year ago for opinion and advice. He was the third child born to consanguineous parents. The mutation analyses were performed for proband, parents, elder sibling and the relatives [maternal aunt and maternal aunt's son (cousin)]. Molecular genetic testing [targeted next-generation sequencing (MiSeq, Illumina method)] was performed by mutation analysis in 15 genes involved. Entire coding exons and their flanking regions of the genes were analysed. Sanger sequencing [(ABI 3730 analyzer by Applied Biosystems)] was performed using primers specific for 43 coding exons of the FANCA gene. A novel splice site mutation, c.3066 + 1G > T, (IVS31 + 1G > T), homozygote was detected by sequencing in the patient. The above sequence variant was identified in heterozygous state in his parents. Further, the above sequence variant was not identified in other family members (elder sibling, maternal aunt and cousin). It is concluded that genetic study should be done if possible in all the cases of suspected FA, including siblings, parents and close blood relatives. It will help us to plan appropriate treatment and also to select suitable donor for hematopoietic stem cell transplantation and to plan for genetic counseling. In addition to the case report, the main focus of this manuscript was to review literature on role of FANCA gene in FA since large number of FANCA mutations and polymorphisms have been identified. PMID:25953249

  6. Effect of low temperature on chlorophyll biosynthesis in albinism line of wheat (Triticum aestivum) FA85.

    PubMed

    Liu, Xiao-Gang; Xu, Hong; Zhang, Jing-Ya; Liang, Guang-Wang; Liu, Ying-Tuan; Guo, Ai-Guang

    2012-07-01

    The 'stage albinism line of winter wheat' FA85 exhibits a severe block in chlorophyll (Chl) biosynthesis with prolonged low-temperature treatment. The correlations between leaf color and low temperature provide more comprehensive understanding of low temperature as an environmental signal that regulate the metabolic changes in the entire Chl-synthesizing pathway. In this study, we investigated differences in Chl biosynthesis between leaves of Aibian1 and FA85 by measuring their Chl precursors and heme content, transcripts for key genes of Chl biosynthesis and key enzyme activities. With prolonged low-temperature treatment, the Chl content gradually decreased, but Chl precursors, including protoporphyrin IX, Mg-protoporphyrin IX and protochlorophyllide (Pchlide), simultaneously accumulated. Parallel to the decline in Chl content, the protoporphyrin IX distribution toward Chl synthesis was less than that in heme synthesis in the leaves of FA85. Corresponding to the change of protoporphyrin IX distribution, the relative changes in magnesium chelatase (EC 6.6.1.1) and ferrochelatase (EC 4.99.1.1) activities in the leaves of FA85 also indirectly reflected channeling of the metabolic flow into heme rather than Chl. A drastic loss in the transcripts for Pchlide oxidoreductase (EC 1.3.1.33) and Chl synthase (EC 2.5.1.62) accounted for a decrease in the metabolic flux and the re-direction of metabolites. The high-level accumulations of Chl precursors and traces of Chl in the leaves of FA85 suggest that a severe block between the steps from Pchlide to Chl formation during Chl biosynthesis is partially derived from the transcriptional downregulation of Pchlide oxidoreductase and Chl synthase.

  7. 75 FR 51657 - Airworthiness Directives; Pratt & Whitney Canada Corp. (P&WC) PW615F-A Turbofan Engines

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-08-23

    ... could result in an unsafe condition. The PW615F-A engine Fuel Filter Bypass Valve installation is very... uncommanded power reduction on one of its engines. Investigation showed that the Fuel Filter Bypass Valve... condition. The PW615F-A engine Fuel Filter Bypass Valve installation is very similar to that of...

  8. An Evaluation Technique for an F/A-18 Aircraft Loads Model Using F/A-18 Systems Research Aircraft Flight Data

    NASA Technical Reports Server (NTRS)

    Olney, Candida D.; Hillebrandt, Heather; Reichenbach, Eric Y.

    2000-01-01

    A limited evaluation of the F/A-18 baseline loads model was performed on the Systems Research Aircraft at NASA Dryden Flight Research Center (Edwards, California). Boeing developed the F/A-18 loads model using a linear aeroelastic analysis in conjunction with a flight simulator to determine loads at discrete locations on the aircraft. This experiment was designed so that analysis of doublets could be used to establish aircraft aerodynamic and loads response at 20 flight conditions. Instrumentation on the right outboard leading edge flap, left aileron, and left stabilator measured the hinge moment so that comparisons could be made between in-flight-measured hinge moments and loads model-predicted values at these locations. Comparisons showed that the difference between the loads model-predicted and in-flight-measured hinge moments was up to 130 percent of the flight limit load. A stepwise regression technique was used to determine new loads derivatives. These derivatives were placed in the loads model, which reduced the error to within 10 percent of the flight limit load. This paper discusses the flight test methodology, a process for determining loads coefficients, and the direct comparisons of predicted and measured hinge moments and loads coefficients.

  9. The role of FaBG3 in fruit ripening and B. cinerea fungal infection of strawberry.

    PubMed

    Li, Qian; Ji, Kai; Sun, Yufei; Luo, Hao; Wang, Hongqing; Leng, Ping

    2013-10-01

    In plants, β-glucosidases (BG) have been implicated in developmental and pathogen defense, and are thought to take part in abscisic acid (ABA) synthesis via hydrolysis of ABA glucose ester to release active ABA; however, there is no genetic evidence for the role of BG genes in ripening and biotic/abiotic stress in fruits. To clarify the role of BG genes in fruit, eight Fa/FvBG genes encoding β-glucosidase were isolated using information from the GenBank strawberry nucleotide database. Of the Fa/FvBG genes examined, expression of FaBG3 was the highest, showing peaks at the mature stage, coincident with the changes observed in ABA content. To verify the role of this gene, we suppressed the expression of FaBG3 via inoculation with Agrobacterium tumefaciens containing tobacco rattle virus carrying a FaBG3 fragment (RNAi). The expression of FaBG3 in FaBG3-RNAi-treated fruit was markedly reduced, and the ABA content was lower than that of the control. FaBG3-RNAi-treated fruit did not exhibit full ripening, and were firmer, had lower sugar content, and were pale compared with the control due to down-regulation of ripening-related genes. FaBG3-RNAi-treated fruit with reduced ABA levels were much more resistant to Botrytis cinerea fungus but were more sensitive to dehydration stress than control fruit. These results indicate that FaBG3 may play key roles in fruit ripening, dehydration stress and B. cinerea fungal infection in strawberries via modulation of ABA homeostasis and transcriptional regulation of ripening-related genes.

  10. Effects of HPV-16 infection on hypopharyngeal squamous cell carcinoma and FaDu cells.

    PubMed

    Lu, Wuhao; Feng, Long; Li, Ping; Wang, Yuanyuan; Du, Yuwen; Chen, Xiaonan; Wu, Shujun; Zhao, Guoqiang; Lou, Weihua

    2016-01-01

    Hypopharyngeal squamous cell carcinoma is a common type of malignant tumor among head and neck squamous cell carcinomas (HNSCCs). Heavy smoking and/or drinking is associated with the development of HNSCC. However, HNSCC also occurs in individuals that do not drink or smoke, possibly due to infection with the human papilloma virus (HPV). HPV-16 has been shown to be closely associated with the occurrence of several types of cancers. However, its role in hypopharyngeal squamous cell carcinoma remains unclear. In the present study, we investigated the effects of HPV-16 on hypopharyngeal squamous cell carcinoma and FaDu cells. Lentiviral vectors were used to establish FaDu cells that expressed the E6 and E7 proteins of HPV-16. We used quantitative reverse transcription-polymerase chain reaction (qRT-PCR) assays and western blotting to detect and determine the levels of expression for E6-E7 mRNAs and proteins. Cell Counting Kit-8 (CCK-8) assays, enzyme-linked immunosorbent assays (ELISA), Transwell assays, and flow cytometry were used to assess the effects of HPV-16 E6-E7 on the proliferation, invasion, metastasis and apoptosis of FaDu cells. Expression of microRNAs was analyzed by qRT-PCR. We found that the expression levels of HPV-16 E6-E7 were increased in FaDu cells transfected with the lentiviral vector compared with that observed in the control cells. In addition, the rates of apoptosis were decreased in the transfected cells, while proliferation was increased. The average numbers of cells penetrating the Matrigel were significantly higher than those for the controls. We detected miR-363 and miR-15a, and their expression levels were significantly increased in the HPV-16-positive patients and in FaDu cells expressing HPV-16 E6-E7. We found that HPV-16 E6-E7 appeared to inhibit apoptosis, and to increase cell proliferation, invasion and metastasis. Furthermore, miR-363 and miR-15a were overexpressed in the hypopharyngeal squamous cell carcinoma samples infected with

  11. Quintuplet Cluster

    NASA Technical Reports Server (NTRS)

    1999-01-01

    Penetrating 25,000 light-years of obscuring dust and myriad stars, NASA's Hubble Space Telescope has provided the clearest view yet of one of the largest young clusters of stars inside our Milky Way galaxy, located less than 100 light-years from the very center of the Galaxy. Having the equivalent mass greater than 10,000 stars like our sun, the monster cluster is ten times larger than typical young star clusters scattered throughout our Milky Way. It is destined to be ripped apart in just a few million years by gravitational tidal forces in the galaxy's core. But in its brief lifetime it shines more brightly than any other star cluster in the Galaxy. Quintuplet Cluster is 4 million years old. It has stars on the verge of blowing up as supernovae. It is the home of the brightest star seen in the galaxy, called the Pistol star. This image was taken in infrared light by Hubble's NICMOS camera in September 1997. The false colors correspond to infrared wavelengths. The galactic center stars are white, the red stars are enshrouded in dust or behind dust, and the blue stars are foreground stars between us and the Milky Way's center. The cluster is hidden from direct view behind black dust clouds in the constellation Sagittarius. If the cluster could be seen from earth it would appear to the naked eye as a 3rd magnitude star, 1/6th of a full moon's diameter apart.

  12. Analysis of Tangential Slot Blowing on F/A-18 Isolated Forebody

    NASA Technical Reports Server (NTRS)

    Gee, Ken; Rizk, Yehia M.; Schiff, Lewis B.

    1995-01-01

    The generation of significant side forces and yawing moments on an F/A-18 fuselage through tangential slot blowing is analyzed using computational fluid dynamics. The effects of freestream Mach number, jet exit conditions, jet length, and jet location are studied. The effects of over- and underblowing on force and moment production are analyzed. Non-time-accurate solutions are obtained to determine the steady-state side forces, yawing moments, and surface pressure distributions generated by tangential slot blowing. Time-accurate solutions are obtained to study the force onset time lag of tangential slot blowing. Comparison with available experimental data from full-scale wind-tunnel and subscale wind-tunnel tests are made. This computational analysis complements the experimental results and provides a detailed understanding of the effects of tangential slot blowing on the flowfield about the isolated F/A-18 forebody. Additionally, it extends the slot-blowing database to transonic maneuvering Mach numbers.

  13. Analysis of tangential slot blowing on F/A-18 isolated forebody

    NASA Technical Reports Server (NTRS)

    Gee, K.; Rizk, Y.; Schiff, L.

    1994-01-01

    Generation of significant side forces and yawing moments on an F/A-18 fuselage through tangential slot blowing is analyzed using computational fluid dynamics. The effects of freestream Mach number, jet exit conditions, jet length, and jet location are studied. The effects of over- and under-blowing on force and moment production are analyzed. Non-time-accurate solutions are obtained to determine the steady-state side forces, yawing moments, and surface pressure distributions generated by tangential slot blowing. Time-accurate solutions are obtained to study the force onset time lag of tangential slot blowing. Comparison with available experimental data from full-scale wind tunnel and sub-scale wind tunnel tests are made. This computational analysis complements the experimental results and provides a detailed understanding of the effects of tangential slot blowing on the flow field about the isolated F/A-18 forebody. Additionally, it extends the slot-blowing database to transonic maneuvering Mach numbers.

  14. Exterior building details of Building B, east façade: embedded wood ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Exterior building details of Building B, east façade: embedded wood beams and interrupted dentil course cornice resulting from the removal of the third floor tuberculosis ward, yard level paneled Dutch door, second level two a typical six-light wood casement windows over a single-panel wood door with four light exits to fire escape; westerly view - San Quentin State Prison, Building 22, Point San Quentin, San Quentin, Marin County, CA

  15. Exterior building details of Building A; west façade: white painted ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Exterior building details of Building A; west façade: white painted brick wall of road and second level, road level: paired four-light casement window and a small single-light wood casement window; second level: four-over-four wood double-hung window and a six-light horizontal pivot over a three-light fixed window; easterly view - San Quentin State Prison, Building 22, Point San Quentin, San Quentin, Marin County, CA

  16. Zebrafish Cacna1fa is required for cone photoreceptor function and synaptic ribbon formation

    PubMed Central

    Jia, Sujuan; Muto, Akira; Orisme, Wilda; Henson, Hannah E.; Parupalli, Chaithanyarani; Ju, Bensheng; Baier, Herwig; Taylor, Michael R.

    2014-01-01

    Mutations in the human CACNA1F gene cause incomplete congenital stationary night blindness type 2 (CSNB2), a non-progressive, clinically heterogeneous retinal disorder. However, the molecular mechanisms underlying CSNB2 have not been fully explored. Here, we describe the positional cloning of a blind zebrafish mutant, wait until dark (wud), which encodes a zebrafish homolog of human CACNA1F. We identified two zebrafish cacna1f paralogs and showed that the cacna1fa transcript (the gene mutated in wud) is expressed exclusively in the photoreceptor layer. We demonstrated that Cacna1fa localizes at the photoreceptor synapse and is absent from wud mutants. Electroretinograms revealed abnormal cone photoreceptor responses from wud mutants, indicating a defect in synaptic transmission. Although there are no obvious morphological differences, we found that wud mutants lacked synaptic ribbons and that wud is essential for the development of synaptic ribbons. We found that Ribeye, the most prominent synaptic ribbon protein, was less abundant and mislocalized in adult wud mutants. In addition to cloning wud, we identified synaptojanin 1 (synj1) as the defective gene in slacker (slak), a blind mutant with floating synaptic ribbons. We determined that Cacna1fa was expressed in slak photoreceptors and that Synj1 was initially expressed wud photoreceptors, but was absent by 5 days postfertilization. Collectively, our data demonstrate that Cacna1fa is essential for cone photoreceptor function and synaptic ribbon formation and reveal a previously unknown yet critical role of L-type voltage-dependent calcium channels in the expression and/or distribution of synaptic ribbon proteins, providing a new model to study the clinical variability in human CSNB2 patients. PMID:24419318

  17. FA composition of heart and skeletal muscle during embryonic development of the king penguin.

    PubMed

    Decrock, Frederic; Groscolas, Rene; Speake, Brian K

    2002-04-01

    Since the yolk lipids of the king penguin (Aptenodytes patagonicus) naturally contain the highest concentrations of DHA and EPA yet reported for the eggs of any avian species, the effects of this (n-3)-rich yolk on the FA profiles of the embryonic heart and skeletal muscle were investigated. The concentrations (mg/g wet tissue) of phospholipid (PL) in the developing heart and leg muscle of the penguin doubled between days 27 and 55 from the beginning of egg incubation (i.e., from the halfway stage of embryonic development to 2 d posthatch), whereas no net increase occurred in pectoral muscle. During this period, the concentration of TAG in heart decreased by half but increased two- and sixfold in leg and pectoral muscle, respectively. The most notable change in cholesteryl ester concentration occurred in pectoral muscle, increasing ninefold between days 27 and 55. Arachidonic acid (ARA) was the major polyunsaturate in PL of the penguin's heart, where it formed about 20% (w/w) of FA at day 55. At the equivalent developmental stage, the heart PL of the chicken contained a 1.3-fold greater proportion of ARA, contained a fifth less DHA, and was almost devoid of EPA, whereas the latter FA was a significant component (7% of FA) of penguin heart PL. Similarly, in PL of leg and pectoral muscle, the chicken displayed about 1.4-fold more ARA, up to 50% less DHA, and far less EPA in comparison with the penguin. Thus, although ARA-rich PL profiles are achieved in the heart and muscle of the penguin embryo, these profiles are significantly affected by the high n-3 content of the yolk. PMID:12030322

  18. Full-Scale Wind Tunnel Studies of F/A-18 Tail Buffet

    NASA Technical Reports Server (NTRS)

    Meyn, Larry A.; James, Kevin D.

    1993-01-01

    Tail buffet studies were conducted on a full-scale, production, F/A-18, fighter aircraft in the 80- by 120-Foot Wind Tunnel of the National Full-Scale Aerodynamic Complex at NASA Ames Research Center in Moffett Field, California. The F/A-18 was tested over an angle-of-attack range of 18deg to 50deg, a side-slip range of -15deg to 15deg, and at wind speeds of up to 100 knots. The maximum speed corresponds to a Reynolds number of 12.3 x 10(exp 6) based on mean aerodynamic chord and a Mach number of 0.15. The port, vertical tail fin was instrumented with thirty-two surface pressure transducers, arranged in four by four arrays on both sides on the fin. The aircraft was also equipped with a removable Leading Edge eXtension (LEX) fence that is used on F/A-18 aircraft to reduce tail buffet loads. Time-averaged, power-spectral analysis results are presented for the tail fin bending moment derived from the integrated pressure field. The results are only for the zero side-slip condition, both with and without the LEX fence. The LEX fence significantly reduces the magnitude of the root-mean-square pressures and bending moments. Scaling issues are addressed by comparing full-scale results for pressures at the 60%-span and 45%-chord location with published results of small-scale, F/A-18 tail-buffet tests. The comparison shows that the tail buffet frequency scales very well with length and velocity. Root-mean-square pressures and power spectra do not scale as well. The LEX fence is shown to reduce tail buffet loads at all model scales.

  19. Development and characterization of a high sensitivity segmented Fast Neutron Spectrometer (FaNS-2)

    NASA Astrophysics Data System (ADS)

    Langford, T. J.; Beise, E. J.; Breuer, H.; Heimbach, C. R.; Ji, G.; Nico, J. S.

    2016-01-01

    We present the development of a segmented fast neutron spectrometer (FaNS-2) based upon plastic scintillator and 3He proportional counters. It was designed to measure both the flux and spectrum of fast neutrons in the energy range of few MeV to 1 GeV. FaNS-2 utilizes capture-gated spectroscopy to identify neutron events and reject backgrounds. Neutrons deposit energy in the plastic scintillator before capturing on a 3He nucleus in the proportional counters. Segmentation improves neutron energy reconstruction while the large volume of scintillator increases sensitivity to low neutron fluxes. A main goal of its design is to study comparatively low neutron fluxes, such as cosmogenic neutrons at the Earth's surface, in an underground environment, or from low-activity neutron sources. In this paper, we present details of its design and construction as well as its characterization with a calibrated 252Cf source and monoenergetic neutron fields of 2.5 MeV and 14 MeV. Detected monoenergetic neutron spectra are unfolded using a Singular Value Decomposition method, demonstrating a 5% energy resolution at 14 MeV. Finally, we discuss plans for measuring the surface and underground cosmogenic neutron spectra with FaNS-2.

  20. Flight Test of the F/A-18 Active Aeroelastic Wing Airplane

    NASA Technical Reports Server (NTRS)

    Voracek, David

    2007-01-01

    A viewgraph presentation of flight tests performed on the F/A active aeroelastic wing airplane is shown. The topics include: 1) F/A-18 AAW Airplane; 2) F/A-18 AAW Control Surfaces; 3) Flight Test Background; 4) Roll Control Effectiveness Regions; 5) AAW Design Test Points; 6) AAW Phase I Test Maneuvers; 7) OBES Pitch Doublets; 8) OBES Roll Doublets; 9) AAW Aileron Flexibility; 10) Phase I - Lessons Learned; 11) Control Law Development and Verification & Validation Testing; 12) AAW Phase II RFCS Envelopes; 13) AAW 1-g Phase II Flight Test; 14) Region I - Subsonic 1-g Rolls; 15) Region I - Subsonic 1-g 360 Roll; 16) Region II - Supersonic 1-g Rolls; 17) Region II - Supersonic 1-g 360 Roll; 18) Region III - Subsonic 1-g Rolls; 19) Roll Axis HOS/LOS Comparison Region II - Supersonic (open-loop); 20) Roll Axis HOS/LOS Comparison Region II - Supersonic (closed-loop); 21) AAW Phase II Elevated-g Flight Test; 22) Region I - Subsonic 4-g RPO; and 23) Phase II - Lessons Learned

  1. Aeroservoelastic Modeling and Validation of a Thrust-Vectoring F/A-18 Aircraft

    NASA Technical Reports Server (NTRS)

    Brenner, Martin J.

    1996-01-01

    An F/A-18 aircraft was modified to perform flight research at high angles of attack (AOA) using thrust vectoring and advanced control law concepts for agility and performance enhancement and to provide a testbed for the computational fluid dynamics community. Aeroservoelastic (ASE) characteristics had changed considerably from the baseline F/A-18 aircraft because of structural and flight control system amendments, so analyses and flight tests were performed to verify structural stability at high AOA. Detailed actuator models that consider the physical, electrical, and mechanical elements of actuation and its installation on the airframe were employed in the analysis to accurately model the coupled dynamics of the airframe, actuators, and control surfaces. This report describes the ASE modeling procedure, ground test validation, flight test clearance, and test data analysis for the reconfigured F/A-18 aircraft. Multivariable ASE stability margins are calculated from flight data and compared to analytical margins. Because this thrust-vectoring configuration uses exhaust vanes to vector the thrust, the modeling issues are nearly identical for modem multi-axis nozzle configurations. This report correlates analysis results with flight test data and makes observations concerning the application of the linear predictions to thrust-vectoring and high-AOA flight.

  2. Full-Scale Wind-Tunnel Studies of F/A-18 Tail Buffet

    NASA Technical Reports Server (NTRS)

    Meyn, Larry A.; James, Kevin D.

    1996-01-01

    Tail buffet studies were conducted on a full-scale, production F/A-18 fighter aircraft in the 80 by 120 ft Wind Tunnel at NASA Ames Research Center. The F/A-18 was tested over an angle-of-attack range of 18-50 deg, and at wind speeds of up to 168 ft/s, corresponding to a Reynolds number of 12.3x10(exp 6) based on mean aerodynamic chord and a Mach number of 0.15. The port, vertical tail fin was instrumented and the aircraft was equipped with a removable leading-edge extension (LEX) fence. Time-averaged, power-spectral analysis results are presented for the tail fin bending moment derived from the integrated pressure field, for the zero side-slip condition, both with and without the LEX fence. The LEX fence significantly reduces the magnitude of the rms pressures and bending moments. Scaling issues are addressed by comparing full-scale results for pressures at the 60%-span and 45%-chord location with small-scale, F/A-18 tail-buffet data. The comparison shows that the tail buffet frequency scales very well with length and velocity. Root-mean-square pressures and power spectra do not scale as well. The LEX fence is shown to reduce tail buffet loads at all model scales.

  3. Wavelet Analyses of F/A-18 Aeroelastic and Aeroservoelastic Flight Test Data

    NASA Technical Reports Server (NTRS)

    Brenner, Martin J.

    1997-01-01

    Time-frequency signal representations combined with subspace identification methods were used to analyze aeroelastic flight data from the F/A-18 Systems Research Aircraft (SRA) and aeroservoelastic data from the F/A-18 High Alpha Research Vehicle (HARV). The F/A-18 SRA data were produced from a wingtip excitation system that generated linear frequency chirps and logarithmic sweeps. HARV data were acquired from digital Schroeder-phased and sinc pulse excitation signals to actuator commands. Nondilated continuous Morlet wavelets implemented as a filter bank were chosen for the time-frequency analysis to eliminate phase distortion as it occurs with sliding window discrete Fourier transform techniques. Wavelet coefficients were filtered to reduce effects of noise and nonlinear distortions identically in all inputs and outputs. Cleaned reconstructed time domain signals were used to compute improved transfer functions. Time and frequency domain subspace identification methods were applied to enhanced reconstructed time domain data and improved transfer functions, respectively. Time domain subspace performed poorly, even with the enhanced data, compared with frequency domain techniques. A frequency domain subspace method is shown to produce better results with the data processed using the Morlet time-frequency technique.

  4. Active Aeroelastic Wing Aerodynamic Model Development and Validation for a Modified F/A-18A

    NASA Technical Reports Server (NTRS)

    Cumming, Stephen B.; Diebler, Corey G.

    2005-01-01

    A new aerodynamic model has been developed and validated for a modified F/A-18A used for the Active Aeroelastic Wing (AAW) research program. The goal of the program was to demonstrate the advantages of using the inherent flexibility of an aircraft to enhance its performance. The research aircraft was an F/A-18A with wings modified to reduce stiffness and a new control system to increase control authority. There have been two flight phases. Data gathered from the first flight phase were used to create the new aerodynamic model. A maximum-likelihood output-error parameter estimation technique was used to obtain stability and control derivatives. The derivatives were incorporated into the National Aeronautics and Space Administration F-18 simulation, validated, and used to develop new AAW control laws. The second phase of flights was used to evaluate the handling qualities of the AAW aircraft and the control law design process, and to further test the accuracy of the new model. The flight test envelope covered Mach numbers between 0.85 and 1.30 and dynamic pressures from 600 to 1250 pound-force per square foot. The results presented in this report demonstrate that a thorough parameter identification analysis can be used to improve upon models that were developed using other means. This report describes the parameter estimation technique used, details the validation techniques, discusses differences between previously existing F/A-18 models, and presents results from the second phase of research flights.

  5. Differential Protection of Cry1Fa Toxin against Spodoptera frugiperda Larval Gut Proteases by Cadherin Orthologs Correlates with Increased Synergism

    PubMed Central

    Rahman, Khalidur; Abdullah, Mohd Amir F.; Ambati, Suresh; Taylor, Milton D.

    2012-01-01

    The Cry proteins produced by Bacillus thuringiensis (Bt) are the most widely used biopesticides effective against a range of crop pests and disease vectors. Like chemical pesticides, development of resistance is the primary threat to the long-term efficacy of Bt toxins. Recently discovered cadherin-based Bt Cry synergists showed the potential to augment resistance management by improving efficacy of Cry toxins. However, the mode of action of Bt Cry synergists is thus far unclear. Here we elucidate the mechanism of cadherin-based Cry toxin synergism utilizing two cadherin peptides, Spodoptera frugiperda Cad (SfCad) and Manduca sexta Cad (MsCad), which differentially enhance Cry1Fa toxicity to Spodoptera frugiperda neonates. We show that differential SfCad- and MsCad-mediated protection of Cry1Fa toxin in the Spodoptera frugiperda midgut correlates with differential Cry1Fa toxicity enhancement. Both peptides exhibited high affinity for Cry1Fa toxin and an increased rate of Cry1Fa-induced pore formation in S. frugiperda. However, only SfCad bound the S. frugiperda brush border membrane vesicle and more effectively prolonged the stability of Cry1Fa toxin in the gut, explaining higher Cry1Fa enhancement by this peptide. This study shows that cadherin fragments may enhance B. thuringiensis toxicity by at least two different mechanisms or a combination thereof: (i) protection of Cry toxin from protease degradation in the insect midgut and (ii) enhancement of pore-forming ability of Cry toxin. PMID:22081566

  6. Galaxy Clusters

    NASA Astrophysics Data System (ADS)

    Miller, Christopher J. Miller

    2012-03-01

    There are many examples of clustering in astronomy. Stars in our own galaxy are often seen as being gravitationally bound into tight globular or open clusters. The Solar System's Trojan asteroids cluster at the gravitational Langrangian in front of Jupiter’s orbit. On the largest of scales, we find gravitationally bound clusters of galaxies, the Virgo cluster (in the constellation of Virgo at a distance of ˜50 million light years) being a prime nearby example. The Virgo cluster subtends an angle of nearly 8◦ on the sky and is known to contain over a thousand member galaxies. Galaxy clusters play an important role in our understanding of theUniverse. Clusters exist at peaks in the three-dimensional large-scale matter density field. Their sky (2D) locations are easy to detect in astronomical imaging data and their mean galaxy redshifts (redshift is related to the third spatial dimension: distance) are often better (spectroscopically) and cheaper (photometrically) when compared with the entire galaxy population in large sky surveys. Photometric redshift (z) [Photometric techniques use the broad band filter magnitudes of a galaxy to estimate the redshift. Spectroscopic techniques use the galaxy spectra and emission/absorption line features to measure the redshift] determinations of galaxies within clusters are accurate to better than delta_z = 0.05 [7] and when studied as a cluster population, the central galaxies form a line in color-magnitude space (called the the E/S0 ridgeline and visible in Figure 16.3) that contains galaxies with similar stellar populations [15]. The shape of this E/S0 ridgeline enables astronomers to measure the cluster redshift to within delta_z = 0.01 [23]. The most accurate cluster redshift determinations come from spectroscopy of the member galaxies, where only a fraction of the members need to be spectroscopically observed [25,42] to get an accurate redshift to the whole system. If light traces mass in the Universe, then the locations

  7. Occupational Clusters.

    ERIC Educational Resources Information Center

    Pottawattamie County School System, Council Bluffs, IA.

    The 15 occupational clusters (transportation, fine arts and humanities, communications and media, personal service occupations, construction, hospitality and recreation, health occupations, marine science occupations, consumer and homemaking-related occupations, agribusiness and natural resources, environment, public service, business and office…

  8. Cluster generator

    DOEpatents

    Donchev, Todor I.; Petrov, Ivan G.

    2011-05-31

    Described herein is an apparatus and a method for producing atom clusters based on a gas discharge within a hollow cathode. The hollow cathode includes one or more walls. The one or more walls define a sputtering chamber within the hollow cathode and include a material to be sputtered. A hollow anode is positioned at an end of the sputtering chamber, and atom clusters are formed when a gas discharge is generated between the hollow anode and the hollow cathode.

  9. Differential modulation of the functionality of white adipose tissue of obese Zucker (fa/fa) rats by the type of protein and the amount and type of fat.

    PubMed

    Díaz-Villaseñor, Andrea; Granados, Omar; González-Palacios, Berenice; Tovar-Palacio, Claudia; Torre-Villalvazo, Ivan; Olivares-García, Verónica; Torres, Nimbe; Tovar, Armando R

    2013-11-01

    Recent evidence indicates that several metabolic abnormalities developed during obesity are associated with the presence of dysfunctional adipose tissue. Diet is a key factor that modulates several functions of adipose tissue; however, each nutrient in the diet produces specific changes. Thus, the aim of this work was to study the effect of the interaction of the type (coconut or soybean oil) and amount (5% or 10%) of fat with the type of dietary protein (casein or soy protein) on the functionality of white adipose tissue of Zucker (fa/fa) rats. The results showed that soybean oil reduced adipocyte size and decreased esterified saturated fatty acids in white adipose tissue. Excess dietary fat also modified the composition of esterified fatty acids in white adipose tissue, increased the secretion of saturated fatty acids to serum from white adipose tissue and reduced the process of fatty acids re-esterification. On the other hand, soy protein sensitized the activation of the hormone-sensitive lipase by increasing the phosphorylation of this enzyme (Ser 563) despite rats fed soy protein were normoglucagonemic, in contrast with rats fed casein that showed hyperglucagonemia but reduced hormone-sensitive lipase phosphorylation. Finally, in white adipose tissue, the interaction between the tested dietary components modulated the transcription/translation process of lipid and carbohydrate metabolism genes via the activity of the PERK-endoplasmic reticulum stress response. Therefore, our results showed that the type of protein and the type and amount of dietary fat selectively modify the activity of white adipose tissue, even in a genetic model of obesity.

  10. A modified F/A-18 in a distinctive red, white and blue paint scheme was showcased during formal roll

    NASA Technical Reports Server (NTRS)

    2002-01-01

    A modified F/A-18 in a distinctive red, white and blue paint scheme was showcased during formal rollout ceremonies for the Active Aeroelastic Wing flight research program at NASA's Dryden Flight Research Center on March 27, 2002.

  11. Purification and Characterization of Botulinum Neurotoxin FA from a Genetically Modified Clostridium botulinum Strain

    PubMed Central

    Pellett, Sabine; Tepp, William H.; Bradshaw, Marite; Kalb, Suzanne R.; Dykes, Janet K.; Lin, Guangyun; Nawrocki, Erin M.; Pier, Christina L.; Barr, John R.; Maslanka, Susan E.

    2016-01-01

    ABSTRACT Botulinum neurotoxins (BoNTs), produced by neurotoxigenic clostridial species, are the cause of the severe disease botulism in humans and animals. Early research on BoNTs has led to their classification into seven serotypes (serotypes A to G) based upon the selective neutralization of their toxicity in mice by homologous antibodies. Recently, a report of a potential eighth serotype of BoNT, designated “type H,” has been controversial. This novel BoNT was produced together with BoNT/B2 in a dual-toxin-producing Clostridium botulinum strain. The data used to designate this novel toxin as a new serotype were derived from culture supernatant containing both BoNT/B2 and novel toxin and from sequence information, although data from two independent laboratories indicated neutralization by antibodies raised against BoNT/A1, and classification as BoNT/FA was proposed. The sequence data indicate a chimeric structure consisting of a BoNT/A1 receptor binding domain, a BoNT/F5 light-chain domain, and a novel translocation domain most closely related to BoNT/F1. Here, we describe characterization of this toxin purified from the native strain in which expression of the second BoNT (BoNT/B) has been eliminated. Mass spectrometry analysis indicated that the toxin preparation contained only BoNT/FA and confirmed catalytic activity analogous to that of BoNT/F5. The in vivo mouse bioassay indicated a specific activity of this toxin of 3.8 × 107 mouse 50% lethal dose (mLD50) units/mg, whereas activity in cultured human neurons was very high (50% effective concentration [EC50] = 0.02 mLD50/well). Neutralization assays in cells and mice both indicated full neutralization by various antibodies raised against BoNT/A1, although at 16- to 20-fold-lower efficiency than for BoNT/A1. IMPORTANCE Botulinum neurotoxins (BoNTs), produced by anaerobic bacteria, are the cause of the potentially deadly, neuroparalytic disease botulism. BoNTs have been classified into seven serotypes

  12. Purification and Characterization of Botulinum Neurotoxin FA from a Genetically Modified Clostridium botulinum Strain.

    PubMed

    Pellett, Sabine; Tepp, William H; Bradshaw, Marite; Kalb, Suzanne R; Dykes, Janet K; Lin, Guangyun; Nawrocki, Erin M; Pier, Christina L; Barr, John R; Maslanka, Susan E; Johnson, Eric A

    2016-01-01

    Botulinum neurotoxins (BoNTs), produced by neurotoxigenic clostridial species, are the cause of the severe disease botulism in humans and animals. Early research on BoNTs has led to their classification into seven serotypes (serotypes A to G) based upon the selective neutralization of their toxicity in mice by homologous antibodies. Recently, a report of a potential eighth serotype of BoNT, designated "type H," has been controversial. This novel BoNT was produced together with BoNT/B2 in a dual-toxin-producing Clostridium botulinum strain. The data used to designate this novel toxin as a new serotype were derived from culture supernatant containing both BoNT/B2 and novel toxin and from sequence information, although data from two independent laboratories indicated neutralization by antibodies raised against BoNT/A1, and classification as BoNT/FA was proposed. The sequence data indicate a chimeric structure consisting of a BoNT/A1 receptor binding domain, a BoNT/F5 light-chain domain, and a novel translocation domain most closely related to BoNT/F1. Here, we describe characterization of this toxin purified from the native strain in which expression of the second BoNT (BoNT/B) has been eliminated. Mass spectrometry analysis indicated that the toxin preparation contained only BoNT/FA and confirmed catalytic activity analogous to that of BoNT/F5. The in vivo mouse bioassay indicated a specific activity of this toxin of 3.8 × 10(7) mouse 50% lethal dose (mLD50) units/mg, whereas activity in cultured human neurons was very high (50% effective concentration [EC50] = 0.02 mLD50/well). Neutralization assays in cells and mice both indicated full neutralization by various antibodies raised against BoNT/A1, although at 16- to 20-fold-lower efficiency than for BoNT/A1. IMPORTANCE Botulinum neurotoxins (BoNTs), produced by anaerobic bacteria, are the cause of the potentially deadly, neuroparalytic disease botulism. BoNTs have been classified into seven serotypes, serotypes A

  13. Central role of FaGAMYB in the transition of the strawberry receptacle from development to ripening.

    PubMed

    Vallarino, José G; Osorio, Sonia; Bombarely, Aureliano; Casañal, Ana; Cruz-Rus, Eduardo; Sánchez-Sevilla, José F; Amaya, Iraida; Giavalisco, Patrick; Fernie, Alisdair R; Botella, Miguel A; Valpuesta, Victoriano

    2015-10-01

    The receptacle of the strawberry (Fragaria × ananassa) fruit accounts for the main properties of the ripe fruit for human consumption. As it ripens, it undergoes changes similar to other fruits in sugar : acid ratio, volatile production and cell wall softening. However, the main regulators of this process have not yet been reported. The white stage marks the initiation of the ripening process, and we had previously reported a peak of expression for a FaGAMYB gene. Transient silencing of FaGAMYB using RNAi and further determination of changes in global gene expression by RNAseq, and composition of primary and secondary metabolites have been used to investigate the role played by this gene during the development of the receptacle. Down-regulation of FaGAMYB caused an arrest in the ripening of the receptacle and inhibited colour formation. Consistent with this, several transcription factors associated with the regulation of flavonoid biosynthetic pathway showed altered expression. FaGAMYB silencing also caused a reduction of ABA biosynthesis and sucrose content. Interestingly, exogenous ABA application to the RNAI-transformed receptacle reversed most defects caused by FaGAMYB down-regulation. The study assigns a key regulatory role to FaGAMYB in the initiation of strawberry receptacle ripening and acting upstream of the known regulator ABA. PMID:26010039

  14. Central role of FaGAMYB in the transition of the strawberry receptacle from development to ripening.

    PubMed

    Vallarino, José G; Osorio, Sonia; Bombarely, Aureliano; Casañal, Ana; Cruz-Rus, Eduardo; Sánchez-Sevilla, José F; Amaya, Iraida; Giavalisco, Patrick; Fernie, Alisdair R; Botella, Miguel A; Valpuesta, Victoriano

    2015-10-01

    The receptacle of the strawberry (Fragaria × ananassa) fruit accounts for the main properties of the ripe fruit for human consumption. As it ripens, it undergoes changes similar to other fruits in sugar : acid ratio, volatile production and cell wall softening. However, the main regulators of this process have not yet been reported. The white stage marks the initiation of the ripening process, and we had previously reported a peak of expression for a FaGAMYB gene. Transient silencing of FaGAMYB using RNAi and further determination of changes in global gene expression by RNAseq, and composition of primary and secondary metabolites have been used to investigate the role played by this gene during the development of the receptacle. Down-regulation of FaGAMYB caused an arrest in the ripening of the receptacle and inhibited colour formation. Consistent with this, several transcription factors associated with the regulation of flavonoid biosynthetic pathway showed altered expression. FaGAMYB silencing also caused a reduction of ABA biosynthesis and sucrose content. Interestingly, exogenous ABA application to the RNAI-transformed receptacle reversed most defects caused by FaGAMYB down-regulation. The study assigns a key regulatory role to FaGAMYB in the initiation of strawberry receptacle ripening and acting upstream of the known regulator ABA.

  15. Improved metabolic status and insulin sensitivity in obese fatty (fa/fa) Zucker rats and Zucker Diabetic Fatty (ZDF) rats treated with the thiazolidinedione, MCC-555

    PubMed Central

    Upton, R; Widdowson, P S; Ishii, S; Tanaka, H; Williams, G

    1998-01-01

    We examined the effect of chronic (21 days) oral treatment with the thiazolidinedione, MCC-555 ((±)-5-[{6-(2-fluorbenzyl)-oxy-2-naphy}methyl]-2,4-thiazolidinedione) on metabolic status and insulin sensitivity in obese (fa/fa) Zucker rats and Zucker Diabetic Fatty (ZDF) rats which display an impaired glucose tolerance (IGT) or overt diabetic symptoms, respectively.MCC-555 treatment to obese Zucker rats (10 and 30 mg kg−1) and diabetic ZDF rats (10 mg kg−1) reduced non-esterified fatty acid concentrations in both rat strains and reduced plasma glucose and triglyceride concentrations in the obese Zucker rats. Liver glycogen concentrations were significantly increased by chronic MCC-555 treatment in both obese Zucker rats (30 mg kg−1 day−1) and diabetic ZDF rats (10 mg kg−1 day−1), as compared with vehicle-treated lean and obese rats and there was a significant increase in hepatic glycogen synthase activity in MCC-555-treated diabetic ZDF rats as compared to vehicle-treated controls.During a euglycaemic hyperinsulinaemic clamp, MCC-555-treated obese Zucker rats and diabetic ZDF rats required significantly higher glucose infusion rates to maintain stable glucose concentrations (2.01±0.19 mg min−1 and 6.42±1.03 mg min−1, respectively) than vehicle-treated obese controls (0.71±0.17 mg min−1 and 2.09±0.71 mg min−1; P<0.05), demonstrating improved insulin sensitivity in both Zucker and ZDF rats. MCC-555 treatment also enhanced insulin-induced suppression of hepatic glucose production in ZDF rats as measured using infusions of [6-3H]-glucose under clamp conditions.In conclusion, we have demonstrated that MCC-555 improves metabolic status and insulin sensitivity in obese Zucker and diabetic ZDF rats. MCC-555 may prove a useful compound for alleviating the metabolic disturbances and IGT associated with insulin resistance in man. PMID:9886762

  16. Myosins FaMyo2B and Famyo2 Affect Asexual and Sexual Development, Reduces Pathogenicity, and FaMyo2B Acts Jointly with the Myosin Passenger Protein FaSmy1 to Affect Resistance to Phenamacril in Fusarium asiaticum.

    PubMed

    Zheng, Zhitian; Liu, Xiumei; Li, Bin; Cai, Yiqiang; Zhu, Yuanye; Zhou, Mingguo

    2016-01-01

    We previously reported that mutations occurred in the gene myosin5 were responsible for resistance to the fungicide phenamacril in Fusarium graminearum. Here, we determined whether there is a functional link between phenamacril resistance and the myosin proteins FaMyo2B and Famyo2 in Fusarium asiaticum, which is the major causal agent of Fusarium head blight in China. We found that FaMyo2B acts jointly with FaSmy1 to affect resistance to phenamacril in F. asiaticum. We also found that FaMyo2B disruption mutant and Famyo2 deletion mutant were defective in hyphal branching, conidiation, and sexual reproduction. ΔFamyo2 also had an enhanced sensitivity to cell wall damaging agents and an abnormal distribution of septa and nuclei. In addition, the FaMyo2B and Famyo2 mutants had reduced pathogenicity on wheat coleoptiles and flowering wheat heads. Taken together, these results reveal that FaMyo2B and Famyo2 are required for several F. asiaticum developmental processes and activities, which help us better understand the resistance mechanism and find the most effective approach to control FHB. PMID:27099966

  17. Myosins FaMyo2B and Famyo2 Affect Asexual and Sexual Development, Reduces Pathogenicity, and FaMyo2B Acts Jointly with the Myosin Passenger Protein FaSmy1 to Affect Resistance to Phenamacril in Fusarium asiaticum

    PubMed Central

    Zheng, Zhitian; Liu, Xiumei; Li, Bin; Cai, Yiqiang; Zhu, Yuanye; Zhou, Mingguo

    2016-01-01

    We previously reported that mutations occurred in the gene myosin5 were responsible for resistance to the fungicide phenamacril in Fusarium graminearum. Here, we determined whether there is a functional link between phenamacril resistance and the myosin proteins FaMyo2B and Famyo2 in Fusarium asiaticum, which is the major causal agent of Fusarium head blight in China. We found that FaMyo2B acts jointly with FaSmy1 to affect resistance to phenamacril in F. asiaticum. We also found that FaMyo2B disruption mutant and Famyo2 deletion mutant were defective in hyphal branching, conidiation, and sexual reproduction. ΔFamyo2 also had an enhanced sensitivity to cell wall damaging agents and an abnormal distribution of septa and nuclei. In addition, the FaMyo2B and Famyo2 mutants had reduced pathogenicity on wheat coleoptiles and flowering wheat heads. Taken together, these results reveal that FaMyo2B and Famyo2 are required for several F. asiaticum developmental processes and activities, which help us better understand the resistance mechanism and find the most effective approach to control FHB. PMID:27099966

  18. Occultifur tropicalis f.a., sp. nov., a novel cystobasidiomycetous yeast species isolated from tropical regions.

    PubMed

    Khunnamwong, Pannida; Surussawadee, Janjira; Jindamorakot, Sasitorn; Ribeiro, José R A; Hagler, Allen N; Limtong, Savitree

    2015-05-01

    Five strains representing a single novel anamorphic yeast species were isolated from sugar cane. Two strains were from tissue (DMKU-SE38, DMKU-SE59(T)) and two from the external surface (DMKU-SP385, DMKU-SP403) of leaves collected in Thailand and the fifth (IMUFRJ 52020) from the rhizoplane of sugar cane in an organically cultivated field in Brazil. On the basis of sequence analysis of the D1/D2 region of the large subunit (LSU) rRNA gene and the internal transcribed spacer (ITS) region, they were classified as representing a single species of the genus Occultifur. The sequences of the D1/D2 region of the LSU rRNA genes and the ITS regions of the five strains were either identical or differed from each other by only one nucleotide substitution. The novel species was related most closely to Occultifur brasiliensis f.a. CBS 12687(T) but with 0.7-1.0% nucleotide substitutions (4-6 nt) in the D1/D2 region of the LSU rRNA gene and 2.5-2.7% nucleotide substitutions (14-15 nt) in the ITS region. The name Occultifur tropicalis f.a., sp. nov. is proposed. The type strain is DMKU-SE59(T) ( =BCC 61184(T) =NBRC 109696(T) =CBS 13389 (T)).

  19. Positional distribution of FA in TAG of enzymatically modified borage and evening primrose oils.

    PubMed

    Senanayake, S P J Namal; Shahidi, Fereidoon

    2002-08-01

    Stereospecific analysis was carried out to establish positional distribution of FA in the TAG of DHA, EPA, and (EPA + DHA)-enriched oils. In this study, TAG of enzymatically modified oils were purified using a silicic acid column. The TAG were then subjected to positional distribution analysis using a modified procedure involving reductive cleavage with Grignard reagent. The results showed that in DHA-enriched borage oil (BO), DHA was randomly distributed over the three positions of TAG, whereas gamma-linolenic acid (GLA) was mainly esterified at the sn-2 and -3 positions. In DHA-enriched evening primrose oil (EPO), however, DHA and GLA were concentrated in the sn-2 position. In EPA-enriched BO, EPA was randomly distributed over the three positions of TAG, similar to that observed for DHA. In EPA-enriched EPO, however, this FA was mainly located at the primary positions (sn-1 and sn-3) of TAG. In both oils, GLA was preferentially esterified at the sn-2 position. In (EPA + DHA)-enriched BO, EPA and DHA were mainly esterified at the sn-1 and -3 positions of TAG, whereas GLA was mainly located at the sn-2 position. In (EPA + DHA)-enriched EPO, GLA was mainly located at the sn-2 and -3 positions; EPA was preferentially esterified at the sn-1 and -3 positions, and DHA was found mainly at the sn-3 position. PMID:12371752

  20. Overview of HATP Experimental Aerodynamics Data for the Baseline F/A-18 Configuration

    NASA Technical Reports Server (NTRS)

    Hall, Robert M.; Murri, Daniel G.; Erickson, Gary E.; Fisher, David F.; Banks, Daniel W.; Lanser, Wendy, R.

    1996-01-01

    Determining the baseline aerodynamics of the F/A-18 was one of the major objectives of the High-Angle-of-Attack Technology Program (HATP). This paper will review the key data bases that have contributed to our knowledge of the baseline aerodynamics and the improvements in test techniques that have resulted from the experimental program. Photographs are given highlighting the forebody and leading-edge-extension (LEX) vortices. Other data representing the impact of Mach and Reynolds numbers on the forebody and LEX vortices will also be detailed. The level of agreement between different tunnels and between tunnels and flight will be illustrated using pressures, forces, and moments measured on a 0.06-scale model tested in the Langley 7- by 10-Foot High Speed Tunnel, a 0.16-scale model in the Langley 30- by 60-Foot Tunnel, a full-scale vehicle in the Ames 80- by 120-Foot Wind Tunnel, and the flight F/A-18 High Alpha Research Vehicle (HARV). Next, creative use of wind tunnel resources that accelerated the validation of the computational fluid dynamics (CFD) codes will be described. Lastly, lessons learned, deliverables, and program conclusions are presented.

  1. Stability analysis of an F/A-18 E/F cable mount m odel

    NASA Technical Reports Server (NTRS)

    Thompson, Nancy; Farmer, Moses

    1994-01-01

    A full-span F/A-18 E/F cable mounted wind tunnel model is part of a flutter clearance program at the NASA Langley Transonic Dynamics Tunnel. Parametric analysis of this model using GRUMCBL software was conducted to assess stability for wind tunnel tests. Two configurations of the F/A-18 E/F were examined. The parameters examined were pulley-cable friction, mach number, dynamic pressure, cable geometry, center of gravity location, cable tension, snubbing the model, drag, and test medium. For the nominal cable geometry (Cable Geometry 1), Configuration One was unstable for cases with higher pulley-cable friction coefficients. A new cable geometry (Cable Geometry 3) was determined in which Configuration One was stable for all cases evaluated. Configuration Two with the nominal center of gravity position was found to be unstable for cases with higher pulley-cable friction coefficients; however, the model was stable when the center of gravity moved forward 1/2. The model was tested using the cable mount system during the initial wind tunnel entry and was stable as predicted.

  2. Occultifur tropicalis f.a., sp. nov., a novel cystobasidiomycetous yeast species isolated from tropical regions.

    PubMed

    Khunnamwong, Pannida; Surussawadee, Janjira; Jindamorakot, Sasitorn; Ribeiro, José R A; Hagler, Allen N; Limtong, Savitree

    2015-05-01

    Five strains representing a single novel anamorphic yeast species were isolated from sugar cane. Two strains were from tissue (DMKU-SE38, DMKU-SE59(T)) and two from the external surface (DMKU-SP385, DMKU-SP403) of leaves collected in Thailand and the fifth (IMUFRJ 52020) from the rhizoplane of sugar cane in an organically cultivated field in Brazil. On the basis of sequence analysis of the D1/D2 region of the large subunit (LSU) rRNA gene and the internal transcribed spacer (ITS) region, they were classified as representing a single species of the genus Occultifur. The sequences of the D1/D2 region of the LSU rRNA genes and the ITS regions of the five strains were either identical or differed from each other by only one nucleotide substitution. The novel species was related most closely to Occultifur brasiliensis f.a. CBS 12687(T) but with 0.7-1.0% nucleotide substitutions (4-6 nt) in the D1/D2 region of the LSU rRNA gene and 2.5-2.7% nucleotide substitutions (14-15 nt) in the ITS region. The name Occultifur tropicalis f.a., sp. nov. is proposed. The type strain is DMKU-SE59(T) ( =BCC 61184(T) =NBRC 109696(T) =CBS 13389 (T)). PMID:25713048

  3. F/A-18 forebody vortex control. Volume 1: Static tests

    NASA Technical Reports Server (NTRS)

    Kramer, Brian R.; Suarez, Carlos J.; Malcolm, Gerald N.; Ayers, Bert F.

    1994-01-01

    A wind tunnel test was conducted on a six percent model of the F/A-18 at the NASA Ames 7 X 10-Foot Low Speed Wind Tunnel. The primary objective of the test was to evaluate several forebody vortex control configurations at high angles of attack in order to determine the most effective method of obtaining well behaved yawing moments, in preparation for the rotary balance test. Both mechanical and pneumatic systems were tested. Single and dual rotating nose tip strakes and a vertical nose strake were tested at different sizes and deflections. A series of jet blowing configurations were located at various fuselage stations, azimuth angles, and pointing angles ranging from straight aft to 60 deg canted inboard. Slot blowing was investigated for several slot lengths and fuselage stations. The effect of blowing rate was tested for both of these pneumatic systems. The most effective configurations were then further tested with a variation of both sideslip angle and Reynolds number over a range of angles of attack from 0 to 60 deg. It was found that a very robust system can be developed that provides yawing moments at angles of attack up to 60 deg that significantly exceeds that available from 30 deg of rudder deflection (F/A-18 maximum) at 0 deg angle of attack.

  4. Computational Analysis of Forebody Tangential Slot Blowing on the F/A-18

    NASA Technical Reports Server (NTRS)

    Gee, Ken; Rizk, Yehia M.; Schiff, Lewis B.; Kutler, Paul (Technical Monitor)

    1994-01-01

    An overview of the computational effort to analyze forebody tangential slot blowing for use on the F/A-18 aircraft is presented. Tangential slot blowing generates side force and yawing moment which may be used to control the aircraft flying at high angle of attack. Computations using the isolated forebody are obtained at full-scale wind tunnel test conditions for direct comparison with available experimental data. The effects of jet exit conditions, jet length, and jet location are also studied using the isolated forebody. In addition, these computations are used to predict the effect of slot blowing at transonic maneuvering flight conditions. The effects of over- and under-blowing on force and moment production are analyzed. Non-time-accurate solutions are obtained to determine the steady-state side force and yawing moments generated by tangential slot blowing. Time-accurate solutions are obtained to study the force onset time lag of tangential slot blowing. The effect of blowing on the burst point location are then analyzed by obtaining computations using the aircraft geometry, which includes the wing, empennage, and faired-over inlets. The effect of blowing on the buffet loads on the vertical tails are analyzed using time-accurate computations. Comparison with available experimental data from full-scale wind tunnel and sub-scale wind tunnel tests are made. This computational analysis compliments the experimental results and provides a detailed understanding of the effects of tangential slot blowing on the flow field about the F/A-18.

  5. Aerostructural Vortical Flow Interactions with Applications to F/A-18 and F-117 Tail Buffet

    NASA Technical Reports Server (NTRS)

    Kandil, Osama A.; Massey, Steven J.; Sheta, Essam F.

    1996-01-01

    The buffet response of the flexible twin-tail configuration of the F/A-18 and a generic F-111 aircraft are computationally simulated and experimentally validated. The problem is a multidisciplinary one which requires the sequential solution of three sets of equations on a multi-block grid structure. The first set is the unsteady, compressible, full Navier-Stokes equations. The second set is the aeroelastic equations for bending and torsional twin-tail responses. The third set is the grid-displacement equations which are used to update the grid coordinates due to the tail deflections. The computational models consist of a 76 deg. swept back, sharp edged delta wing of aspect ratio of one and a swept-back F/A-18 or F-117 twin-tail. The configuration is pitched at 30 deg. angle-of-attack. The problem is solved for the initial flow conditions with the twin tails kept rigid. Next, the aeroelastic equations of the tails are turned on along with the grid-displacement equations to solve for the bending and torsional tails responses due to the unsteady loads produced by the vortex breakdown flow of the leading-edge vortex cores of the delta wing. Several spanwise locations of the twin tails are investigated. The computational results are validated using several existing experimental data.

  6. F/A-18 Performance Benefits Measured During the Autonomous Formation Flight Project

    NASA Technical Reports Server (NTRS)

    Vachon, M. Jake; Ray, Ronald J.; Walsh, Kevin R.; Ennix, Kimberly

    2003-01-01

    The Autonomous Formation Flight (AFF) project at the NASA Dryden Flight Research Center (Edwards, California) investigated performance benefits resulting from formation flight, such as reduced aerodynamic drag and fuel consumption. To obtain data on performance benefits, a trailing F/A-18 airplane flew within the wing tip-shed vortex of a leading F/A-18 airplane. The pilot of the trail airplane used advanced station-keeping technology to aid in positioning the trail airplane at precise locations behind the lead airplane. The specially instrumented trail airplane was able to obtain accurate fuel flow measurements and to calculate engine thrust and vehicle drag. A maneuver technique developed for this test provided a direct comparison of performance values while flying in and out of the vortex. Based on performance within the vortex as a function of changes in vertical, lateral, and longitudinal positioning, these tests explored design-drivers for autonomous stationkeeping control systems. Observations showed significant performance improvements over a large range of trail positions tested. Calculations revealed maximum drag reductions of over 20 percent, and demonstrated maximum reductions in fuel flow of just over 18 percent.

  7. Composting of food waste subjected to hydrothermal pretreatment and inoculated with Paecilomyces sp. FA13.

    PubMed

    Nakasaki, Kiyohiko; Mimoto, Hiroshi; Tran, Quyen Ngoc Minh; Oinuma, Akiko

    2015-03-01

    Food waste collected from restaurants, convenience stores, and food-processing factories was mixed with sawdust and subjected to hydrothermal pretreatment at 180°C for 30min to prepare compost raw material. Furan compounds such as 5-HMF (5-hydroxymethyl furfural) and furfural were produced at concentration levels of approximately 8 and 0.5mg/g-ds, respectively, through hydrothermal pretreatment. The furan compounds inhibited the activity of composting microorganisms, thus delaying the start of organic matter degradation during composting. A newly identified fungus, Paecilomyces sp. FA13, which possesses the ability to degrade furan compounds, was isolated and used as an inoculum for the composting of the raw material prepared by hydrothermal pretreatment. By inoculating the FA13 into the compost raw material at 10(5)CFU/g-ds, the degradation of furan compounds was accelerated. As a result, bacterial activity, which contributed to composting, was enhanced, significantly promoting the start of vigorous degradation of organic materials.

  8. Positional distribution of FA in TAG of enzymatically modified borage and evening primrose oils.

    PubMed

    Senanayake, S P J Namal; Shahidi, Fereidoon

    2002-08-01

    Stereospecific analysis was carried out to establish positional distribution of FA in the TAG of DHA, EPA, and (EPA + DHA)-enriched oils. In this study, TAG of enzymatically modified oils were purified using a silicic acid column. The TAG were then subjected to positional distribution analysis using a modified procedure involving reductive cleavage with Grignard reagent. The results showed that in DHA-enriched borage oil (BO), DHA was randomly distributed over the three positions of TAG, whereas gamma-linolenic acid (GLA) was mainly esterified at the sn-2 and -3 positions. In DHA-enriched evening primrose oil (EPO), however, DHA and GLA were concentrated in the sn-2 position. In EPA-enriched BO, EPA was randomly distributed over the three positions of TAG, similar to that observed for DHA. In EPA-enriched EPO, however, this FA was mainly located at the primary positions (sn-1 and sn-3) of TAG. In both oils, GLA was preferentially esterified at the sn-2 position. In (EPA + DHA)-enriched BO, EPA and DHA were mainly esterified at the sn-1 and -3 positions of TAG, whereas GLA was mainly located at the sn-2 position. In (EPA + DHA)-enriched EPO, GLA was mainly located at the sn-2 and -3 positions; EPA was preferentially esterified at the sn-1 and -3 positions, and DHA was found mainly at the sn-3 position.

  9. Adaptive Augmenting Control Flight Characterization Experiment on an F/A-18

    NASA Technical Reports Server (NTRS)

    VanZwieten, Tannen S.; Orr, Jeb S.; Wall, John H.; Gilligan, Eric T.

    2014-01-01

    This paper summarizes the Adaptive Augmenting Control (AAC) flight characterization experiments performed using an F/A-18 (TN 853). AAC was designed and developed specifically for launch vehicles, and is currently part of the baseline autopilot design for NASA's Space Launch System (SLS). The scope covered here includes a brief overview of the algorithm (covered in more detail elsewhere), motivation and benefits of flight testing, top-level SLS flight test objectives, applicability of the F/A-18 as a platform for testing a launch vehicle control design, test cases designed to fully vet the AAC algorithm, flight test results, and conclusions regarding the functionality of AAC. The AAC algorithm developed at Marshall Space Flight Center is a forward loop gain multiplicative adaptive algorithm that modifies the total attitude control system gain in response to sensed model errors or undesirable parasitic mode resonances. The AAC algorithm provides the capability to improve or decrease performance by balancing attitude tracking with the mitigation of parasitic dynamics, such as control-structure interaction or servo-actuator limit cycles. In the case of the latter, if unmodeled or mismodeled parasitic dynamics are present that would otherwise result in a closed-loop instability or near instability, the adaptive controller decreases the total loop gain to reduce the interaction between these dynamics and the controller. This is in contrast to traditional adaptive control logic, which focuses on improving performance by increasing gain. The computationally simple AAC attitude control algorithm has stability properties that are reconcilable in the context of classical frequency-domain criteria (i.e., gain and phase margin). The algorithm assumes that the baseline attitude control design is well-tuned for a nominal trajectory and is designed to adapt only when necessary. Furthermore, the adaptation is attracted to the nominal design and adapts only on an as-needed basis

  10. The Relationship between Adult Occupational Preferences and Childhood Gender Nonconformity among Samoan Women, Men, and Fa'afafine.

    PubMed

    Semenyna, Scott W; Vasey, Paul L

    2016-09-01

    Previous research has found that sex differences in occupational preferences are both substantial and cross-culturally universal. Androphilic males tend to display "gender-shifted" occupational preferences, with relatively female-typical interests. Past research has overwhelmingly relied on Western samples; this article offers new insights from a non-Western setting. Known locally as fa'afafine, androphilic males in Samoa occupy a third-gender category. Data were collected in Samoa from 103 men, 103 women, and 103 fa'afafine regarding occupational preferences and recalled childhood gender nonconformity (CGN). A substantial sex difference was observed in the occupational preferences of men and women (d = 2.04). Interestingly, women and fa'afafine did not differ in their preferences (p = 0.89), indicating a complete gender inversion of occupational preferences in the latter. Although there was no correlation between women's CGN and masculine occupational preferences, there was a significant correlation (r = -0.62) between these variables in both men and fa'afafine. Among males (both men and fa'afafine), increased CGN was associated with preference for feminine occupations. The present research corroborates past findings and furnishes support for the conclusion that female-typical occupational preferences are a cross-culturally invariant aspect of male androphilia.

  11. Interspecific hybridization does not affect the level of fluctuating asymmetry (FA) in the Drosophila bipectinata species complex.

    PubMed

    Banerjee, Parul; Singh, B N

    2015-08-01

    The Drosophila bipectinata species complex comprises of four very closely related species namely D. bipectinata, D. parabipectinata, D. malerkotliana and D. pseudoananassae. It was found that irrespective of the evolutionary divergence among the species, FA which is reflective of the developmental precision remains nearly same in four species. During the present study, the level of FA in different morphological traits was studied in interspecific hybrids and compared with that of parental species with the view that it would throw light on the degree of divergence between the parental species. If they have not diverged much, the interspecific hybrids may have a similar FA level, incompatibilities between their genomes being negligible. On the other hand, if there is substantial divergence, the level of FA may be higher due to incompatibility between the genomes of the parental species. The morphological traits taken were sternopleural bristle number and wing length in both males and females and ovariole number and sex-comb tooth number in females and males respectively. However, except in a few cases, we could not detect any significant differences in the level of FA in hybrids as compared to pure species. On the other hand, a number of abnormalities like poor viability, dystrophied ovaries, asymmetrical eyes etc., could be detected in hybrids from crosses involving D. pseudoananassae as one of the parents. Therefore, we conclude that specific developmental pathways are more susceptible to developmental disturbances due to genomic incompatibilities than the large complex system bringing about developmental stability.

  12. Impact of FaSSIF on the solubility and dissolution-/permeation rate of a poorly water-soluble compound.

    PubMed

    Frank, Kerstin J; Westedt, Ulrich; Rosenblatt, Karin M; Hölig, Peter; Rosenberg, Jörg; Mägerlein, Markus; Brandl, Martin; Fricker, Gert

    2012-08-30

    The poorly water-soluble drug ABT-102, a potent TRPV1 (transient receptor potential cation channel subfamily V member 1) antagonist, was investigated in terms of its solubility and dissolution-permeation rate across Caco-2 cell monolayers in the presence and absence of fasted state simulated intestinal fluid (FaSSIF). ABT-102 showed a more than 30-fold higher apparent solubility in FaSSIF, compared to Hank's balanced salt solution (HBSS). On the other hand, the amount of truly dissolved API in the suspension, as assessed by inverse dialysis, was found hardly influenced by FaSSIF. Neither the drug nor FaSSIF adversely affected cell viability or integrity of the Caco-2 monolayer. P-gp-inhibition experiments confirmed that the drug was not a substrate of the export pump. The flux of ABT-102 across the Caco-2 barrier was found virtually the same in FaSSIF and in buffer, i.e. in vitro overall dissolution-/permeation rate of ABT-102 from suspensions appears not affected by its enhanced apparent solubility due to association with TC/PC-micelles. PMID:22579958

  13. Incorporation of either molybdenum or tungsten into formate dehydrogenase from Desulfovibrio alaskensis NCIMB 13491; EPR assignment of the proximal iron-sulfur cluster to the pterin cofactor in formate dehydrogenases from sulfate-reducing bacteria.

    PubMed

    Brondino, Carlos D; Passeggi, Mario C G; Caldeira, Jorge; Almendra, Maria J; Feio, Maria J; Moura, Jose J G; Moura, Isabel

    2004-03-01

    We report the characterization of the molecular properties and EPR studies of a new formate dehydrogenase (FDH) from the sulfate-reducing organism Desulfovibrio alaskensis NCIMB 13491. FDHs are enzymes that catalyze the two-electron oxidation of formate to carbon dioxide in several aerobic and anaerobic organisms. D. alaskensis FDH is a heterodimeric protein with a molecular weight of 126+/-2 kDa composed of two subunits, alpha=93+/-3 kDa and beta=32+/-2 kDa, which contains 6+/-1 Fe/molecule, 0.4+/-0.1 Mo/molecule, 0.3+/-0.1 W/molecule, and 1.3+/-0.1 guanine monophosphate nucleotides. The UV-vis absorption spectrum of D. alaskensis FDH is typical of an iron-sulfur protein with a broad band around 400 nm. Variable-temperature EPR studies performed on reduced samples of D. alaskensis FDH showed the presence of signals associated with the different paramagnetic centers of D. alaskensis FDH. Three rhombic signals having g-values and relaxation behavior characteristic of [4Fe-4S] clusters were observed in the 5-40 K temperature range. Two EPR signals with all the g-values less than two, which accounted for less than 0.1 spin/protein, typical of mononuclear Mo(V) and W(V), respectively, were observed. The signal associated with the W(V) ion has a larger deviation from the free electron g-value, as expected for tungsten in a d(1) configuration, albeit with an unusual relaxation behavior. The EPR parameters of the Mo(V) signal are within the range of values typically found for the slow-type signal observed in several Mo-containing proteins belonging to the xanthine oxidase family of enzymes. Mo(V) resonances are split at temperatures below 50 K by magnetic coupling with one of the Fe/S clusters. The analysis of the inter-center magnetic interaction allowed us to assign the EPR-distinguishable iron-sulfur clusters with those seen in the crystal structure of a homologous enzyme.

  14. Transonic Experimental Observations of Abrupt Wing Stall on an F/A-18E Model (Invited)

    NASA Technical Reports Server (NTRS)

    McMillin, S. Naomi; Hall, Robert M.; Lamar, John E.

    2003-01-01

    A transonic wind tunnel test of an 8% F/A-18E model was conducted in the NASA Langley Research Center (LaRC) 16 ft Transonic Tunnel (16-ft TT) to investigate on-surface flow physics during stall. The technical approach employed focused on correlating static (or time-averaged) and unsteady wind-tunnel test data to the unsteady wing-stall events using force, moment, pressure, and pressure-sensitive-paint measurements. This paper focuses on data obtained on the pre-production configuration of the F/A-18E aircraft at Mach number of 0.90. The flow unsteadiness occurring on the wing as the wing went through the stall process was captured using the time history of balance and pressure measurements and by calculating the root mean square (RMS) for a number of instrument signals. The second step was to gather global perspectives on the pressures influencing the wing stall process. The abrupt wing stall experienced by the 8% F/A-18E Model was observed to be an unsteady event triggered by the rapid advancement of separation, which had migrated forward from the trailing edge, to the leading-edge flap hingeline over a very small increment in angle of attack. The angle of attack at which this stall occurred varied, from run to run, over an 1 deg increment. The abrupt wing stall was observed, using pressure-sensitive-paint, to occur simultaneously on both wing panels or asymmetrically. The pressure-sensitive paint data and wingroot bending moment data were essential in providing insight to the flow structures occurring over the wing and the possible asymmetry of those flow structures. A repeatability analysis conducted on eight runs of static data provided a quick and inexpensive examination of the unsteady aerodynamic characteristics of abrupt wing stall. The results of the repeatability analysis agreed extremely well with data obtained using unsteady measurement techniques. This approach could be used to identify test conditions for more complex unsteady data measurements using

  15. Field-Evolved Mode 1 Resistance of the Fall Armyworm to Transgenic Cry1Fa-Expressing Corn Associated with Reduced Cry1Fa Toxin Binding and Midgut Alkaline Phosphatase Expression

    PubMed Central

    Jakka, Siva R. K.; Gong, Liang; Hasler, James; Banerjee, Rahul; Sheets, Joel J.; Narva, Kenneth; Blanco, Carlos A.

    2015-01-01

    Insecticidal protein genes from the bacterium Bacillus thuringiensis (Bt) are expressed by transgenic Bt crops (Bt crops) for effective and environmentally safe pest control. The development of resistance to these insecticidal proteins is considered the most serious threat to the sustainability of Bt crops. Resistance in fall armyworm (Spodoptera frugiperda) populations from Puerto Rico to transgenic corn producing the Cry1Fa insecticidal protein resulted, for the first time in the United States, in practical resistance, and Bt corn was withdrawn from the local market. In this study, we used a field-collected Cry1Fa corn-resistant strain (456) of S. frugiperda to identify the mechanism responsible for field-evolved resistance. Binding assays detected reduced Cry1Fa, Cry1Ab, and Cry1Ac but not Cry1Ca toxin binding to midgut brush border membrane vesicles (BBMV) from the larvae of strain 456 compared to that from the larvae of a susceptible (Ben) strain. This binding phenotype is descriptive of the mode 1 type of resistance to Bt toxins. A comparison of the transcript levels for putative Cry1 toxin receptor genes identified a significant downregulation (>90%) of a membrane-bound alkaline phosphatase (ALP), which translated to reduced ALP protein levels and a 75% reduction in ALP activity in BBMV from 456 compared to that of Ben larvae. We cloned and heterologously expressed this ALP from susceptible S. frugiperda larvae and demonstrated that it specifically binds with Cry1Fa toxin. This study provides a thorough mechanistic description of field-evolved resistance to a transgenic Bt crop and supports an association between resistance and reduced Cry1Fa toxin binding and levels of a putative Cry1Fa toxin receptor, ALP, in the midguts of S. frugiperda larvae. PMID:26637593

  16. Field-Evolved Mode 1 Resistance of the Fall Armyworm to Transgenic Cry1Fa-Expressing Corn Associated with Reduced Cry1Fa Toxin Binding and Midgut Alkaline Phosphatase Expression.

    PubMed

    Jakka, Siva R K; Gong, Liang; Hasler, James; Banerjee, Rahul; Sheets, Joel J; Narva, Kenneth; Blanco, Carlos A; Jurat-Fuentes, Juan L

    2015-12-04

    Insecticidal protein genes from the bacterium Bacillus thuringiensis (Bt) are expressed by transgenic Bt crops (Bt crops) for effective and environmentally safe pest control. The development of resistance to these insecticidal proteins is considered the most serious threat to the sustainability of Bt crops. Resistance in fall armyworm (Spodoptera frugiperda) populations from Puerto Rico to transgenic corn producing the Cry1Fa insecticidal protein resulted, for the first time in the United States, in practical resistance, and Bt corn was withdrawn from the local market. In this study, we used a field-collected Cry1Fa corn-resistant strain (456) of S. frugiperda to identify the mechanism responsible for field-evolved resistance. Binding assays detected reduced Cry1Fa, Cry1Ab, and Cry1Ac but not Cry1Ca toxin binding to midgut brush border membrane vesicles (BBMV) from the larvae of strain 456 compared to that from the larvae of a susceptible (Ben) strain. This binding phenotype is descriptive of the mode 1 type of resistance to Bt toxins. A comparison of the transcript levels for putative Cry1 toxin receptor genes identified a significant downregulation (>90%) of a membrane-bound alkaline phosphatase (ALP), which translated to reduced ALP protein levels and a 75% reduction in ALP activity in BBMV from 456 compared to that of Ben larvae. We cloned and heterologously expressed this ALP from susceptible S. frugiperda larvae and demonstrated that it specifically binds with Cry1Fa toxin. This study provides a thorough mechanistic description of field-evolved resistance to a transgenic Bt crop and supports an association between resistance and reduced Cry1Fa toxin binding and levels of a putative Cry1Fa toxin receptor, ALP, in the midguts of S. frugiperda larvae.

  17. Structural redox control in a 7Fe ferredoxin isolated from Desulfovibrio alaskensis.

    PubMed

    Grazina, Raquel; de Sousa, Patrícia M Paes; Brondino, Carlos D; Carepo, Marta S P; Moura, Isabel; Moura, José J G

    2011-08-01

    The redox behaviour of a ferredoxin (Fd) from Desulfovibrio alaskensis was characterized by electrochemistry. The protein was isolated and purified, and showed to be a tetramer containing one [3Fe-4S] and one [4Fe-4S] centre. This ferredoxin has high homology with FdI from Desulfovibrio vulgaris Miyazaki and Hildenborough and FdIII from Desulfovibrio africanus. From differential pulse voltammetry the following signals were identified: [3Fe-4S](+1/0) (E(0')=-158±5mV); [4Fe-4S](+2/+1) (E(0')=-474±5mV) and [3Fe-4S](0/-2) (E(0')=-660±5mV). The effect of pH on these signals showed that the reduced [3Fe-4S](0) cluster has a pK'(red)(')=5.1±0.1, the [4Fe-4S](+2/+1) centre is pH independent, and the [3Fe-4S](0/-2) reduction is accompanied by the binding of two protons. The ability of the [3Fe-4S](0) cluster to be converted into a new [4Fe-4S] cluster was proven. The redox potential of the original [4Fe-4S] centre showed to be dependent on the formation of the new [4Fe-4S] centre, which results in a positive shift (ca. 70mV) of the redox potential of the original centre. Being most [Fe-S] proteins involved in electron transport processes, the electrochemical characterization of their clusters is essential to understand their biological function. Complementary EPR studies were performed.

  18. Wing Torsional Stiffness Tests of the Active Aeroelastic Wing F/A-18 Airplane

    NASA Technical Reports Server (NTRS)

    Lokos, William A.; Olney, Candida D.; Crawford, Natalie D.; Stauf, Rick; Reichenbach, Eric Y.

    2002-01-01

    The left wing of the Active Aeroelastic Wing (AAW) F/A-18 airplane has been ground-load-tested to quantify its torsional stiffness. The test has been performed at the NASA Dryden Flight Research Center in November 1996, and again in April 2001 after a wing skin modification was performed. The primary objectives of these tests were to characterize the wing behavior before the first flight, and provide a before-and-after measurement of the torsional stiffness. Two streamwise load couples have been applied. The wing skin modification is shown to have more torsional flexibility than the original configuration has. Additionally, structural hysteresis is shown to be reduced by the skin modification. Data comparisons show good repeatability between the tests.

  19. Poly(3-Hydroxybutyrate) Synthesis Genes in Azotobacter sp. Strain FA8

    PubMed Central

    Pettinari, M. Julia; Vázquez, Gustavo J.; Silberschmidt, Daniel; Rehm, Bernd; Steinbüchel, Alexander; Méndez, Beatriz S.

    2001-01-01

    Genes responsible for the synthesis of poly(3-hydroxybutyrate) (PHB) in Azotobacter sp. FA8 were cloned and analyzed. A PHB polymerase gene (phbC) was found downstream from genes coding for β-ketothiolase (phbA) and acetoacetyl-coenzyme A reductase (phbB). A PHB synthase mutant was obtained by gene inactivation and used for genetic studies. The phbC gene from this strain was introduced into Ralstonia eutropha PHB-4 (phbC-negative mutant), and the recombinant accumulated PHB when either glucose or octanoate was used as a source of carbon, indicating that this PHB synthase cannot incorporate medium-chain-length hydroxyalkanoates into PHB. PMID:11679365

  20. Aeroelastic modeling for the FIT (Functional Integration Technology) team F/A-18 simulation

    NASA Technical Reports Server (NTRS)

    Zeiler, Thomas A.; Wieseman, Carol D.

    1989-01-01

    As part of Langley Research Center's commitment to developing multidisciplinary integration methods to improve aerospace systems, the Functional Integration Technology (FIT) team was established to perform dynamics integration research using an existing aircraft configuration, the F/A-18. An essential part of this effort has been the development of a comprehensive simulation modeling capability that includes structural, control, and propulsion dynamics as well as steady and unsteady aerodynamics. The structural and unsteady aerodynamics contributions come from an aeroelastic mode. Some details of the aeroelastic modeling done for the Functional Integration Technology (FIT) team research are presented. Particular attention is given to work done in the area of correction factors to unsteady aerodynamics data.

  1. Aeroelastic modeling for the FIT team F/A-18 simulation

    NASA Technical Reports Server (NTRS)

    Zeiler, Thomas A.; Wieseman, Carol D.

    1989-01-01

    Some details of the aeroelastic modeling of the F/A-18 aircraft done for the Functional Integration Technology (FIT) team's research in integrated dynamics modeling and how these are combined with the FIT team's integrated dynamics model are described. Also described are mean axis corrections to elastic modes, the addition of nonlinear inertial coupling terms into the equations of motion, and the calculation of internal loads time histories using the integrated dynamics model in a batch simulation program. A video tape made of a loads time history animation was included as a part of the oral presentation. Also discussed is work done in one of the areas of unsteady aerodynamic modeling identified as needing improvement, specifically, in correction factor methodologies for improving the accuracy of stability derivatives calculated with a doublet lattice code.

  2. F/A-18 and F-16 forebody vortex control, static and rotary-balance results

    NASA Technical Reports Server (NTRS)

    Kramer, Brian; Smith, Brooke

    1994-01-01

    The results from research on forebody vortex control on both the F/A-18 and the F-16 aircraft will be shown. Several methods of forebody vortex control, including mechanical and pneumatic schemes, will be discussed. The wind tunnel data includes both static and rotary balance data for forebody vortex control. Time lags between activation or deactivation of the pneumatic control and when the aircraft experiences the resultant forces are also discussed. The static (non-rotating) forces and pressures are then compared to similar configurations tested in the NASA Langley and DTRC Wind Tunnel, the NASA Ames 80'x120' Wind Tunnel, and in flight on the High Angle of Attack Research Vehicle (HARV).

  3. Nakazawaea siamensis f.a., sp. nov., a yeast species isolated from phylloplane.

    PubMed

    Kaewwichian, Rungluk; Limtong, Savitree

    2014-01-01

    Strain DMKU-RK467(T), representing a novel yeast species, was isolated from the external surface of sugar cane leaves collected in Thailand. On the basis of morphological, biochemical, physiological and chemotaxonomic characteristics, and sequence analysis of the D1/D2 region of the LSU rRNA gene and the internal transcribed spacer (ITS) region, strain DMKU-RK467(T) was assigned to a novel species of the genus Nakazawaea. The novel species was related most closely to the type strain of Candida wickerhamii but they differed by 1.9 % nucleotide substitutions in the D1/D2 region of the LSU rRNA gene and by 5.2 % nucleotide substitutions in the ITS region. The name Nakazawaea siamensis f.a., sp. nov. is proposed (type strain DMKU-RK467(T) = BCC 50734(T) = NBRC 108903(T) = CBS 12569(T)). PMID:24052626

  4. Wind Tunnel Visualization of the Flow Over a Full-Scale F/A-18 Aircraft

    NASA Technical Reports Server (NTRS)

    Lanser, Wendy R.; Botha, Gavin J.; James, Kevin D.; Crowder, James P.; Schmitz, Fredric H. (Technical Monitor)

    1994-01-01

    The proposed paper presents flow visualization performed during experiments conducted on a full-scale F/A-18 aircraft in the 80- by 120-Foot Wind-Tunnel at NASA Ames Research Center. This investigation used both surface and off-surface flow visualization techniques to examine the flow field on the forebody, canopy, leading edge extensions (LEXs), and wings. The various techniques used to visualize the flow field were fluorescent tufts, flow cones treated with reflective material, smoke in combination with a laser light sheet, and a video imaging system. The flow visualization experiments were conducted over an angle of attack range from 20deg to 45deg and over a sideslip range from -10deg to 10deg. The results show regions of attached and separated flow on the forebody, canopy, and wings. Additionally, the vortical flow is clearly visible over the leading-edge extensions, canopy, and wings.

  5. Control Law-Control Allocation Interaction: F/A-18 PA Simulation Test - Bed

    NASA Technical Reports Server (NTRS)

    Durham, Wayne; Nelson, Mark

    2001-01-01

    This report documents the first stage of research into Control Law - Control Allocation Interactions. A three-year research effort was originally proposed: 1. Create a desktop flight simulation environment under which experiments related to the open questions may be conducted. 2. Conduct research to determine which aspects of control allocation have impact upon control law design that merits further research. 3. Conduct research into those aspects of control allocation identified above, and their impacts upon control law design. Simulation code was written utilizing the F/A-18 airframe in the power approach (PA) configuration. A dynamic inversion control law was implemented and used to drive a state-of-the-art control allocation subroutine.

  6. Worst-Case Flutter Margins from F/A-18 Aircraft Aeroelastic Data

    NASA Technical Reports Server (NTRS)

    Lind, Rick; Brenner, Marty

    1997-01-01

    An approach for computing worst-case flutter margins has been formulated in a robust stability framework. Uncertainty operators are included with a linear model to describe modeling errors and flight variations. The structured singular value, micron, computes a stability margin which directly accounts for these uncertainties. This approach introduces a new method of computing flutter margins and an associated new parameter for describing these margins. The micron margins are robust margins which indicate worst-case stability estimates with respect to the defined uncertainty. Worst-case flutter margins are computed for the F/A-18 SRA using uncertainty sets generated by flight data analysis. The robust margins demonstrate flight conditions for flutter may lie closer to the flight envelope than previously estimated by p-k analysis.

  7. Comparing the performance of FA, DFA and DMA using different synthetic long-range correlated time series

    PubMed Central

    Shao, Ying-Hui; Gu, Gao-Feng; Jiang, Zhi-Qiang; Zhou, Wei-Xing; Sornette, Didier

    2012-01-01

    Notwithstanding the significant efforts to develop estimators of long-range correlations (LRC) and to compare their performance, no clear consensus exists on what is the best method and under which conditions. In addition, synthetic tests suggest that the performance of LRC estimators varies when using different generators of LRC time series. Here, we compare the performances of four estimators [Fluctuation Analysis (FA), Detrended Fluctuation Analysis (DFA), Backward Detrending Moving Average (BDMA), and Centred Detrending Moving Average (CDMA)]. We use three different generators [Fractional Gaussian Noises, and two ways of generating Fractional Brownian Motions]. We find that CDMA has the best performance and DFA is only slightly worse in some situations, while FA performs the worst. In addition, CDMA and DFA are less sensitive to the scaling range than FA. Hence, CDMA and DFA remain “The Methods of Choice” in determining the Hurst index of time series. PMID:23150785

  8. Cluster headache

    PubMed Central

    2010-01-01

    Introduction The revised International Headache Society (IHS) criteria for cluster headache are: attacks of severe or very severe, strictly unilateral pain, which is orbital, supraorbital, or temporal pain, lasting 15 to 180 minutes and occurring from once every other day to eight times daily. Methods and outcomes We conducted a systematic review and aimed to answer the following clinical questions: What are the effects of interventions to abort cluster headache? What are the effects of interventions to prevent cluster headache? We searched: Medline, Embase, The Cochrane Library, and other important databases up to June 2009 (Clinical Evidence reviews are updated periodically; please check our website for the most up-to-date version of this review). We included harms alerts from relevant organisations, such as the US Food and Drug Administration (FDA) and the UK Medicines and Healthcare products Regulatory Agency (MHRA). Results We found 23 systematic reviews, RCTs, or observational studies that met our inclusion criteria. We performed a GRADE evaluation of the quality of evidence for interventions. Conclusions In this systematic review, we present information relating to the effectiveness and safety of the following interventions: baclofen (oral); botulinum toxin (intramuscular); capsaicin (intranasal); chlorpromazine; civamide (intranasal); clonidine (transdermal); corticosteroids; ergotamine and dihydroergotamine (oral or intranasal); gabapentin (oral); greater occipital nerve injections (betamethasone plus xylocaine); high-dose and high-flow-rate oxygen; hyperbaric oxygen; leuprolide; lidocaine (intranasal); lithium (oral); melatonin; methysergide (oral); octreotide (subcutaneous); pizotifen (oral); sodium valproate (oral); sumatriptan (oral, subcutaneous, and intranasal); topiramate (oral); tricyclic antidepressants (TCAs); verapamil; and zolmitriptan (oral and intranasal). PMID:21718584

  9. Rapid evaluation and quality control of next generation sequencing data with FaQCs

    SciTech Connect

    Lo, Chien -Chi; Chain, Patrick S. G.

    2014-12-01

    Background: Next generation sequencing (NGS) technologies that parallelize the sequencing process and produce thousands to millions, or even hundreds of millions of sequences in a single sequencing run, have revolutionized genomic and genetic research. Because of the vagaries of any platform's sequencing chemistry, the experimental processing, machine failure, and so on, the quality of sequencing reads is never perfect, and often declines as the read is extended. These errors invariably affect downstream analysis/application and should therefore be identified early on to mitigate any unforeseen effects. Results: Here we present a novel FastQ Quality Control Software (FaQCs) that can rapidly process large volumes of data, and which improves upon previous solutions to monitor the quality and remove poor quality data from sequencing runs. Both the speed of processing and the memory footprint of storing all required information have been optimized via algorithmic and parallel processing solutions. The trimmed output compared side-by-side with the original data is part of the automated PDF output. We show how this tool can help data analysis by providing a few examples, including an increased percentage of reads recruited to references, improved single nucleotide polymorphism identification as well as de novo sequence assembly metrics. Conclusion: FaQCs combines several features of currently available applications into a single, user-friendly process, and includes additional unique capabilities such as filtering the PhiX control sequences, conversion of FASTQ formats, and multi-threading. The original data and trimmed summaries are reported within a variety of graphics and reports, providing a simple way to do data quality control and assurance.

  10. Polarization of large cometary dust aggregates: computations with FaSTMM

    NASA Astrophysics Data System (ADS)

    Markkanen, Johannes; Penttilä, Antti; Muinonen, Karri

    2016-10-01

    We model light scattering by cometary dust with a special emphasis on polarization effects of large aggregated non-spherical dust particles. The contribution of large aggregates to the scattering characteristics of cometary dust is not well studied due to the rapid growth of computational time with respect to the number of grains in an aggregate when modelled by conventional numerical techniques (Mackowski, Mishchenko, JQSRT, 112(13), 2182-2192, 2011). To speed up computations, we apply our novel Fast Superposition T-Matrix Method (FaSTMM) that can deal with aggregates consisting of large numbers of non-spherical inhomogeneous grains.The FaSTMM is based on two individual solvers. First, the so-called T-matrices of the grains in an aggregate are determined by the method-of-moments solution of the Maxwell equations based on the volume-integral-equation approach. Once the T-matrices have been computed and stored, the second solver, i.e., the superposition T-matrix method, accelerated by the multilevel-fast-multipole algorithm (MLFMA), is employed to solve for the scattering properties of the entire aggregate consisting of arbitrarily rotated grains whose T-matrices had been computed by the first solver. Such an approach allows for efficient computations of ensample-averaged light-scattering features of aggregated dust particles. The MLFMA acceleration works especially well for sparse, fractal-like aggregates within a large volume. The method is exact in the sense that no approximation is made for the physics described by the classical electromagnetic scattering theory.As a dust model, we use porous aggregates with non-spherical grains consisting of a silicate core covered by organic refractory mantle. Thus, the dust particle model is consistent with the cometary dust formation model by Greenberg (Greenberg, Hage, Astrophys. J. 361, 260-274, 1990).Acknowledgments. Research supported by the European Research Council (ERC, grant Nr. 320773).

  11. Rapid evaluation and quality control of next generation sequencing data with FaQCs

    DOE PAGES

    Lo, Chien -Chi; Chain, Patrick S. G.

    2014-12-01

    Background: Next generation sequencing (NGS) technologies that parallelize the sequencing process and produce thousands to millions, or even hundreds of millions of sequences in a single sequencing run, have revolutionized genomic and genetic research. Because of the vagaries of any platform's sequencing chemistry, the experimental processing, machine failure, and so on, the quality of sequencing reads is never perfect, and often declines as the read is extended. These errors invariably affect downstream analysis/application and should therefore be identified early on to mitigate any unforeseen effects. Results: Here we present a novel FastQ Quality Control Software (FaQCs) that can rapidly processmore » large volumes of data, and which improves upon previous solutions to monitor the quality and remove poor quality data from sequencing runs. Both the speed of processing and the memory footprint of storing all required information have been optimized via algorithmic and parallel processing solutions. The trimmed output compared side-by-side with the original data is part of the automated PDF output. We show how this tool can help data analysis by providing a few examples, including an increased percentage of reads recruited to references, improved single nucleotide polymorphism identification as well as de novo sequence assembly metrics. Conclusion: FaQCs combines several features of currently available applications into a single, user-friendly process, and includes additional unique capabilities such as filtering the PhiX control sequences, conversion of FASTQ formats, and multi-threading. The original data and trimmed summaries are reported within a variety of graphics and reports, providing a simple way to do data quality control and assurance.« less

  12. Delta-like 1/Fetal Antigen-1 (Dlk1/FA1) Is a Novel Regulator of Chondrogenic Cell Differentiation via Inhibition of the Akt Kinase-dependent Pathway*

    PubMed Central

    Chen, Li; Qanie, Diyako; Jafari, Abbas; Taipaleenmaki, Hanna; Jensen, Charlotte H.; Säämänen, Anna-Marja; Sanz, Maria Luisa Nueda; Laborda, Jorge; Abdallah, Basem M.; Kassem, Moustapha

    2011-01-01

    Delta-like 1 (Dlk1, also known as fetal antigen-1, FA1) is a member of Notch/Delta family that inhibits adipocyte and osteoblast differentiation; however, its role in chondrogenesis is still not clear. Thus, we overexpressed Dlk1/FA1 in mouse embryonic ATDC5 cells and tested its effects on chondrogenic differentiation. Dlk1/FA1 inhibited insulin-induced chondrogenic differentiation as evidenced by reduction of cartilage nodule formation and gene expression of aggrecan, collagen Type II and X. Similar effects were obtained either by using Dlk1/FA1-conditioned medium or by addition of a purified, secreted, form of Dlk1 (FA1) directly to the induction medium. The inhibitory effects of Dlk1/FA1 were dose-dependent and occurred irrespective of the chondrogenic differentiation stage: proliferation, differentiation, maturation, or hypertrophic conversion. Overexpression or addition of the Dlk1/FA1 protein to the medium strongly inhibited the activation of Akt, but not the ERK1/2, or p38 MAPK pathways, and the inhibition of Akt by Dlk1/FA1 was mediated through PI3K activation. Interestingly, inhibition of fibronectin expression by siRNA rescued the Dlk1/FA1-mediated inhibition of Akt, suggesting interaction of Dlk1/FA1 and fibronectin in chondrogenic cells. Our results identify Dlk1/FA1 as a novel regulator of chondrogenesis and suggest Dlk1/FA1 acts as an inhibitor of the PI3K/Akt pathways that leads to its inhibitory effects on chondrogenesis. PMID:21724852

  13. Controlled clinical comparison of plastic and glass bottles of BacT/ALERT FA medium for culturing organisms from blood of adult patients.

    PubMed

    Petti, Cathy A; Mirrett, Stanley; Woods, Christopher W; Reller, L Barth

    2005-04-01

    A new, clear-plastic nonvented aerobic FA bottle, designed to prevent breakage, has been developed for the BacT/ALERT blood culture system. We assessed the new plastic FA bottle by comparing its performance with that of the current glass FA bottle for recovery of microorganisms and time to detection of growth in blood samples obtained for culture from adult patients with suspected bloodstream infections. We conclude that the BacT/ALERT plastic and glass FA bottles are comparable for recovery of microorganisms and that the safety advantage of plastic bottles can be achieved without compromising performance.

  14. [Risk of nasopharyngeal cancer, Leukemia and other tumors in a cohort of employees and students potentially exposed to (FA) formaldehyde in University laboratories].

    PubMed

    Sernia, S; Di Folco, F; Altrudo, P; Sbriccoli, B; Sestili, C; Colamesta, V; Del Buono, S; Michetti, A; Ortis, M; Dawodu, A; Villari, P; La Torre, G

    2016-01-01

    FA was recently classified as carcinogen of second class (category 1B). A retrospective cohort study was conducted for the evaluation of the association between exposure to FA and cancer in professionally potentially exposed in a University setting. The cohort was composed of 140 exposed to FA and 364 not exposed in the period 1999-2015. The results showed no cancers of naso-pharynx and leukemias or lymphomas both among exposed and not exposed. Moreover, the exposure to FA is not significantly associated to an increase of other types of tumors. PMID:27212573

  15. Water-tunnel study results of a TF/A-18 and F/A-18 canopy flow visualization

    NASA Technical Reports Server (NTRS)

    Johnson, Steven A.; Fisher, David F.

    1990-01-01

    A water tunnel study examining the influence of canopy shape on canopy and leading edge extension flow patterns was initiated. The F/A-18 single-place canopy model and the TF/A-18 two place canopy model were the study subjects. Plan view and side view photographs showing the flow patterns created by injected colored dye are presented for 0 deg and 5 deg sideslip angles. Photographs taken at angle of attack and sideslip conditions correspond to test departure points found in flight test. Flight experience has shown that the TF/A-18 airplane departs in regions where the F/A-18 airplane is departure-resistant. The study results provide insight into the differences in flow patterns which may influence the resulting aerodynamics of the TF/A-18 and F/A-18 aircraft. It was found that at 0 deg sideslip, the TF/A-18 model has more downward flow on the sides of the canopy than the F/A-18 model. This could be indicative of flow from the leading edge extension (LEX) vortexes impinging on the sides of the wider TF/A-18 canopy. In addition, the TF/A-18 model has larger areas of asymmetric separated and unsteady flow on the LEXs and fuselage, possibly indicating a lateral and directional destabilizing effect at the conditions studied.

  16. Determination of the refractive index difference caused by the birefringence of FA (II) centers in KCl:Li

    NASA Astrophysics Data System (ADS)

    Silfsten, Pertti; Ketolainen, Pertti

    1991-11-01

    A method is described for determining the refractive index difference caused by the birefringence of oriented FA (II) centers in KCl:Li crystals. It is shown that the portion induced by the birefringence can be separated from an absorption spectrum measured through a polarizer-analyzer system. From this portion the refractive index difference can then be calculated with ease.

  17. Production Support Flight Control Computers: Research Capability for F/A-18 Aircraft at Dryden Flight Research Center

    NASA Technical Reports Server (NTRS)

    Carter, John F.

    1997-01-01

    NASA Dryden Flight Research Center (DFRC) is working with the United States Navy to complete ground testing and initiate flight testing of a modified set of F/A-18 flight control computers. The Production Support Flight Control Computers (PSFCC) can give any fleet F/A-18 airplane an in-flight, pilot-selectable research control law capability. NASA DFRC can efficiently flight test the PSFCC for the following four reasons: (1) Six F/A-18 chase aircraft are available which could be used with the PSFCC; (2) An F/A-18 processor-in-the-loop simulation exists for validation testing; (3) The expertise has been developed in programming the research processor in the PSFCC; and (4) A well-defined process has been established for clearing flight control research projects for flight. This report presents a functional description of the PSFCC. Descriptions of the NASA DFRC facilities, PSFCC verification and validation process, and planned PSFCC projects are also provided.

  18. Behind the Façade of Fee-Free education: Shadow Education and Its Implications for Social Justice

    ERIC Educational Resources Information Center

    Bray, Mark; Kwo, Ora

    2013-01-01

    Most governments, at an official level, espouse the principles of the 1948 Universal Declaration of Human Rights. Among its statements is that education shall be free, at least in the elementary and fundamental stages. Yet while the façade of government education systems presents an image that instruction is free of charge, families across the…

  19. The optimization of FA/O barrier slurry with respect to removal rate selectivity on patterned Cu wafers

    NASA Astrophysics Data System (ADS)

    Yi, Hu; Yan, Li; Yuling, Liu; Yangang, He

    2016-02-01

    Because the polishing of different materials is required in barrier chemical mechanical planarization (CMP) processes, the development of a kind of barrier slurry with improved removal rate selectivity for Cu/barrier/TEOS would reduce erosion and dishing defects on patterned Cu wafers. In this study, we developed a new benzotriazole-free barrier slurry named FA/O barrier slurry, containing 20 mL/L of the chelating agent FA/O, 5 mL/L surfactant, and a 1:5 concentration of abrasive particles. By controlling the polishing slurry ingredients, the removal rate of different materials could be controlled. For process integration considerations, the effect of the FA/O barrier slurry on the dielectric layer of the patterned Cu wafer was investigated. After CMP processing by the FA/O barrier slurry, the characteristics of the dielectric material were tested. The results showed that the dielectric characteristics met demands for industrial production. The current leakage was of pA scale. The resistance and capacitance were 2.4 kω and 2.3 pF, respectively. The dishing and erosion defects were both below 30 nm in size. CMP-processed wafers using this barrier slurry could meet industrial production demands. Project supported by the Special Project Items No. 2 in National Long-Term Technology Development Plan (No. 2009ZX02308), the Natural Science Foundation of Hebei Province (No. F2012202094), and the Doctoral Program Foundation of Xinjiang Normal University Plan (No. XJNUBS1226).

  20. A Hypomorphic PALB2 Allele Gives Rise to an Unusual Form of FA-N Associated with Lymphoid Tumour Development

    PubMed Central

    Byrd, Philip J.; Stewart, Grant. S.; Smith, Anna; Eaton, Charlotte; Taylor, Alexander J.; Guy, Chloe; Eringyte, Ieva; Fooks, Peggy; Last, James I.; Horsley, Robert; Oliver, Antony W.; Janic, Dragana; Dokmanovic, Lidija; Stankovic, Tatjana; Taylor, A. Malcolm R.

    2016-01-01

    Patients with biallelic truncating mutations in PALB2 have a severe form of Fanconi anaemia (FA-N), with a predisposition for developing embryonal-type tumours in infancy. Here we describe two unusual patients from a single family, carrying biallelic PALB2 mutations, one truncating, c.1676_1677delAAinsG;(p.Gln559ArgfsTer2), and the second, c.2586+1G>A; p.Thr839_Lys862del resulting in an in frame skip of exon 6 (24 amino acids). Strikingly, the affected individuals did not exhibit the severe developmental defects typical of FA-N patients and initially presented with B cell non-Hodgkin lymphoma. The expressed p.Thr839_Lys862del mutant PALB2 protein retained the ability to interact with BRCA2, previously unreported in FA-N patients. There was also a large increased chromosomal radiosensitivity following irradiation in G2 and increased sensitivity to mitomycin C. Although patient cells were unable to form Rad51 foci following exposure to either DNA damaging agent, U2OS cells, in which the mutant PALB2 with in frame skip of exon 6 was induced, did show recruitment of Rad51 to foci following damage. We conclude that a very mild form of FA-N exists arising from a hypomorphic PALB2 allele. PMID:26990772

  1. A NASA F/A-18, participating in the Automated Aerial Refueling (AAR) project, flies over the Dryden

    NASA Technical Reports Server (NTRS)

    2002-01-01

    A NASA F/A-18 is participating in the Automated Aerial Refueling (AAR) project. The 300-gallon aerial refueling store seen on the belly of the aircraft carries fuel and a refueling drogue. This aircraft acts as a tanker in the study to develop an aerodynamic model for future automated aerial refueling, especially of unmanned vehicles.

  2. Viewing time measures of sexual orientation in Samoan cisgender men who engage in sexual interactions with fa'afafine.

    PubMed

    Petterson, Lanna J; Dixson, Barnaby J; Little, Anthony C; Vasey, Paul L

    2015-01-01

    Androphilia refers to attraction to adult males, whereas gynephilia refers to attraction to adult females. The current study employed self-report and viewing time (response time latency) measures of sexual attraction to determine the sexual orientation of Samoan cisgender men (i.e., males whose gender presentation and identity is concordant with their biological sex) who engage in sexual interactions with transgender male androphiles (known locally as fa'afafine) compared to: (1) Samoan cisgender men who only engage in sexual interactions with women, and (2) fa'afafine. As expected, both measures indicated that cisgender men who only engaged in sexual interactions with women exhibited a gynephilic pattern of sexual attraction, whereas fa'afafine exhibited an androphilic one. In contrast, both measures indicated that cisgender men who engaged in sexual interactions with fa'afafine demonstrated a bisexual pattern of sexual attraction. Most of the cisgender men who exhibited bisexual viewing times did not engage in sexual activity with both men and women indicating that the manner in which bisexual patterns of sexual attraction manifest behaviorally vary from one culture to the next. PMID:25679961

  3. Study of the degradation activity and the strategies to promote the bioavailability of phenanthrene by Sphingomonas paucimobilis strain 20006FA.

    PubMed

    Coppotelli, Bibiana M; Ibarrolaza, Agustin; Dias, Romina L; Del Panno, Maria T; Berthe-Corti, Luise; Morelli, Irma S

    2010-02-01

    The present study describes the phenanthrene-degrading activity of Sphingomonas paucimobilis 20006FA and its ability to promote the bioavailability of phenanthrene. S. paucimobilis 20006FA was isolated from a phenanthrene-contaminated soil microcosm. The strain was able to grow in liquid mineral medium saturated with phenanthrene as the sole carbon source, showing high phenanthrene elimination (52.9% of the supplied phenanthrene within 20 days). The accumulation of 1-hydroxy-2-naphthoic acid and salicylic acid as major phenanthrene metabolites and the capacity of the strain to grow with sodium salicylate as the sole source of carbon and energy indicated that the S. paucimobilis 20006FA possesses a complete phenanthrene degradation pathway. However, under the studied conditions, the strain was able to mineralize only the 10% of the consumed phenanthrene. Investigations on the cell ability to promote bioavailability of phenanthrene showed that the S. paucimobilis strain 20006FA exhibited low cell hydrophobicity (0.13), a pronounced chemotaxis toward phenanthrene, and it was able to reduce the surface tension of mineral liquid medium supplemented with phenanthrene as sole carbon source. Scanning electron micrographs revealed that: (1) in suspension cultures, cells formed flocks and showed small vesicles on the cell surface and (2) cells were also able to adhere to phenanthrene crystals and to produce biofilms. Clearly, the strain seems to exhibit two different mechanisms to enhance phenanthrene bioavailability: biosurfactant production and adhesion to the phenanthrene crystals.

  4. A Hypomorphic PALB2 Allele Gives Rise to an Unusual Form of FA-N Associated with Lymphoid Tumour Development.

    PubMed

    Byrd, Philip J; Stewart, Grant S; Smith, Anna; Eaton, Charlotte; Taylor, Alexander J; Guy, Chloe; Eringyte, Ieva; Fooks, Peggy; Last, James I; Horsley, Robert; Oliver, Antony W; Janic, Dragana; Dokmanovic, Lidija; Stankovic, Tatjana; Taylor, A Malcolm R

    2016-03-01

    Patients with biallelic truncating mutations in PALB2 have a severe form of Fanconi anaemia (FA-N), with a predisposition for developing embryonal-type tumours in infancy. Here we describe two unusual patients from a single family, carrying biallelic PALB2 mutations, one truncating, c.1676_1677delAAinsG;(p.Gln559ArgfsTer2), and the second, c.2586+1G>A; p.Thr839_Lys862del resulting in an in frame skip of exon 6 (24 amino acids). Strikingly, the affected individuals did not exhibit the severe developmental defects typical of FA-N patients and initially presented with B cell non-Hodgkin lymphoma. The expressed p.Thr839_Lys862del mutant PALB2 protein retained the ability to interact with BRCA2, previously unreported in FA-N patients. There was also a large increased chromosomal radiosensitivity following irradiation in G2 and increased sensitivity to mitomycin C. Although patient cells were unable to form Rad51 foci following exposure to either DNA damaging agent, U2OS cells, in which the mutant PALB2 with in frame skip of exon 6 was induced, did show recruitment of Rad51 to foci following damage. We conclude that a very mild form of FA-N exists arising from a hypomorphic PALB2 allele. PMID:26990772

  5. 2 CFR 200.411 - Adjustment of previously negotiated indirect (F&A) cost rates containing unallowable costs.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 2 Grants and Agreements 1 2014-01-01 2014-01-01 false Adjustment of previously negotiated indirect (F&A) cost rates containing unallowable costs. 200.411 Section 200.411 Grants and Agreements Office of Management and Budget Guidance for Grants and Agreements OFFICE OF MANAGEMENT AND BUDGET GUIDANCE Reserved UNIFORM ADMINISTRATIVE...

  6. Two strawberry miR159 family members display developmental-specific expression patterns in the fruit receptacle and cooperatively regulate Fa-GAMYB.

    PubMed

    Csukasi, Fabiana; Donaire, Livia; Casañal, Ana; Martínez-Priego, Llúcia; Botella, Miguel A; Medina-Escobar, Nieves; Llave, César; Valpuesta, Victoriano

    2012-07-01

    • We have reported previously that the gibberellin (GA) content in strawberry receptacle is high, peaking at specific stages, pointing to a role of this hormone in fruit development. In Arabidopsis, miR159 levels are dependent on GA concentration. This prompted us to investigate the role of two members of the miR159 family and their putative strawberry target gene, GAMYB, in relation to changes in GA content during the course of fruit development. • The highest expression level of the two Fa-MIR159 genes was in the fruit's receptacle tissue, with dramatic changes observed throughout development. The lowest levels of total mature miR159 (a and b) were observed during the white stage of receptacle development, which was concurrent with the highest expression of Fa-GAMYB. A functional interaction between miR159 and Fa-GAMYB has been demonstrated in receptacle tissue. • The application of bioactive GA (i.e. GA(3) ) to strawberry plants caused the down-regulated expression of Fa-MIR159a, but the expression of Fa-MIR159b was not affected significantly. Clear discrepancies between Fa-MIR159b and mature Fa-miR159b levels were indicative of post-transcriptional regulation of Fa-MIR159b gene expression. • We propose that Fa-miR159a and Fa-miR159b interact with Fa-GAMYB during the course of strawberry receptacle development, and that they act in a cooperative fashion to respond, in part, to changes in GA endogenous levels.

  7. Evaluation of F/A-18A HARV inlet flow analysis with flight data

    NASA Technical Reports Server (NTRS)

    Smith, C. Frederic; Podleski, Steve D.; Barankiewicz, Wendy S.; Zeleznik, Susan Z.

    1995-01-01

    The F/A-18A aircraft has experienced engine stalls at high angles-of-attack and yaw flight conditions which were outside of its flight envelope. Future aircraft may be designed to operate routinely in this flight regime. Therefore, it is essential that an understanding of the inlet flow field at these flight conditions be obtained. Due to the complex interactions of the fuselage and inlet flow fields, a study of the flow within the inlet must also include external effects. Full Navier-Stokes (FNS) calculations on the F/A-18A High Alpha Research Vehicle (HARV) inlet for several angles-of-attack with sideslip and free stream Mach numbers have been obtained. The predicted forebody/fuselage surface static pressures agreed well with flight data. The surface static pressures along the inlet lip are in good agreement with the numerical predictions. The major departure in agreement is along the bottom of the lip at 30 deg and 60 deg angle-of-attack where a possible streamwise flow separation is not being predicted by the code. The circumferential pressure distributions at the engine face are in very good agreement with the numerical results. The variation in surface static pressure in the circumferential direction is very small with the exception of 60 angle-of-attack. Although the simulation does not include the effect of the engine, it appears that this omission has a second order effect on the circumferential pressure distribution. An examination of the unsteady flight test data base has shown that the secondary vortex migrates a significant distance with time. In fact, the extent of this migration increases with angle-of-attack with increasing levels of distortion. The effects of the engine on this vortex movement is unknown. This implies that the level of flow unsteadiness increases with increasing distortion. Since the computational results represent an asymptotic solution driven by steady boundary conditions, these numerical results may represent an arbitrary point

  8. PARC3D calculations of the F/A-18A HARV inlet vortex generators

    NASA Technical Reports Server (NTRS)

    Podleski, Steve D.

    1995-01-01

    NASA Lewis Research Center is currently engaged in a research effort as a team member of the High Alpha Technology Program within the NASA agency. This program uses a specially-equipped F/A-18A aircraft called the High Alpha Research Vehicle (HARV), in an effort to improve the maneuverability of high performance military aircraft at low-subsonic-speed, high-angle-of-attack conditions. The overall objective of the NASA Lewis effort is to develop inlet analysis technology towards efficient airflow delivery to the engine during these maneuvers. One portion of this inlet analysis technology uses computational fluid dynamics to predict installed inlet performance. Most of the F/A-18A HARV geometry, which includes the ramp/splitter plate, side diverter and slot, inlet lip and upper diverter, and deflected leading-edge flap has been modeled. The empennage and rear fuselage have not. A pair of vortex generators located on the bottom wall of the inlet were not modeled initially. These vortex generators were installed to alleviate any flow separation that may be induced by the wheel well protrusion into the inlet wall. Calculations completed with the PARC3D code showed that the pressure recovery has been underpredicted and the flow distortion over-predicted. To improve the correlation of PARC3D predictions with flight and wind tunnel tests, the vortex generators were included in the grid geometry and the results are presented in this report. The grid totals 27 blocks or 1.3 million grid points for the half model, which includes the vortex generator grid blocks. Two flight cases were calculated, a high speed case with a Mach number of 0.8 and angle of attack of 3.4; and a low speed case with a Mach number of 0.43 and angle of attack of 32.2. The vortex generators have a significant effect on the inlet boundary layers at high speed, low angle of attack; and have no effect at low speed, high angle of attack.

  9. Cytotoxicity of amino alcohols to rat hepatoma-derived Fa32 cells.

    PubMed

    Scheers, Ellen M; Forsby, Anna; Dierickx, Paul J

    2002-01-01

    Amino alcohols are used as emulsifying agents in dry-cleaning soaps, wax removers, cosmetics, paints and insecticides. The cytotoxicities of 12 amino alcohols, which differed in chain length, position of the amino and alcohol groups, and the presence of an additional phenyl group, were determined by the neutral red uptake inhibition assay with normally cultured, glutathione-depleted or antioxidant-enriched Fa32 rat hepatoma-derived cells. Glutathione depletion and antioxidant enrichment were achieved by including 50(M L-buthionine-S,R-sulphoximine (BSO) or 100(M (-tocopherol acetate (vitamin E) in the culture medium for 24 hours before and during the assay. The cytotoxicity of the amino alcohols observed after treatment for 24 hours was expressed as the concentration of compound needed to induce a 50% reduction in neutral red uptake (NI50). The observed NI50 values ranged from 3mM to 30mM. The individual stereoisomers and a racemic mixture of 1-amino-2-propanol exhibited similar cytotoxicities (with normally cultured Fa32 cells, and vitamin E- and BSO-treated cultures). Similar NI50 values for D-(+)-2-amino-1-propanol, 3-amino-1-propanol and the L-, D- or DL- forms of 1-amino-2-propanol, indicated that the position of the amino group had little influence on the cytotoxicities of the amino alcohols. In contrast, the position of the hydroxyl group appeared to play an important role for the toxicity of the compound, as indicated by the significantly different NI50 values for 4-amino-1-butanol and 4-amino-2-butanol. An additional phenyl group greatly increased the cytotoxicity of 2-amino-1,3-propanediol. For most of the compounds, cytotoxicity increased when GSH was depleted, and decreased when the cells were enriched with vitamin E. This indicated that most of the tested chemicals interact with GSH, either directly or indirectly, by processes which generate oxygen free-radicals. Decreased toxicity was found for most of the chemicals administered to vitamin E

  10. Environmental and health effects of nanomaterials in nanotextiles and façade coatings.

    PubMed

    Som, Claudia; Wick, Peter; Krug, Harald; Nowack, Bernd

    2011-08-01

    Engineered nanomaterials (ENM) are expected to hold considerable potential for products that offer improved or novel functionalities. For example, nanotechnologies could open the way for the use of textile products outside their traditional fields of applications, for example, in the construction, medical, automobile, environmental and safety technology sectors. Consequently, nanotextiles could become ubiquitous in industrial and consumer products in future. Another ubiquitous field of application for ENM is façade coatings. The environment and human health could be affected by unintended release of ENM from these products. The product life cycle and the product design determine the various environmental and health exposure situations. For example, ENM unintentionally released from geotextiles will probably end up in soils, whereas ENM unintentionally released from T-shirts may come into direct contact with humans and end up in wastewater. In this paper we have assessed the state of the art of ENM effects on the environment and human health on the basis of selected environmental and nanotoxicological studies and on our own environmental exposure modeling studies. Here, we focused on ENM that are already applied or may be applied in future to textile products and façade coatings. These ENM's are mainly nanosilver (nano-Ag), nano titanium dioxide (nano-TiO(2)), nano silica (nano-SiO(2)), nano zinc oxide (nano-ZnO), nano alumina (nano-Al(2)O(3)), layered silica (e.g. montmorillonite, Al(2)[(OH)(2)/Si(4)O(10)]nH(2)O), carbon black, and carbon nanotubes (CNT). Knowing full well that innovators have to take decisions today, we have presented some criteria that should be useful in systematically analyzing and interpreting the state of the art on the effects of ENM. For the environment we established the following criteria: (1) the indication for hazardous effects, (2) dissolution in water increases/decreases toxic effects, (3) tendency for agglomeration or sedimentation

  11. FaCE: a tool for three body Faddeev calculations with core excitation

    NASA Astrophysics Data System (ADS)

    Thompson, I. J.; Nunes, F. M.; Danilin, B. V.

    2004-08-01

    FaCE is a self contained program, with namelist input, that solves the three body Faddeev equations. It enables the inclusion of excitation of one of the three bodies, whilst the other two remain inert. It is particularly useful for obtaining the binding energies and bound state structure compositions of light exotic nuclei treated as three-body systems, given the three effective two body interactions. A large variety of forms for these interactions may be defined, and supersymmetric transformations of these potentials may be calculated whenever two body states need to be removed due to Pauli blocking. Program summaryTitle of program: FaCE (Faddeev with Core Excitation) Catalogue identifier: ADTW Program summary URL:http://cpc.cs.qub.ac.uk/summaries/ADTW Program obtainable from: CPC Program Library, Queen's University of Belfast, N. Ireland Computers: The code is designed to run on any Unix/Linux workstation or PC. Operating systems: Linux or UNIX Program language used: Fortran-90 Numerical libraries used: Source code for 6 routines from the NAG and BLAS libraries is included to enable independent compilation. Memory required to execute with typical data: 9 Mbytes of RAM memory and 12 MB of hard disk space. No. of bits in a word: 32 or 64 No. of bytes in distributed program, including test data, etc.: 116 514 No. of lines in distributed program, including test data, etc.: 15 574 Distribution format: tar gzip file Nature of physical problem: The program calculates eigenenergies and eigenstates for the three body problem by solving the Faddeev equations. Method of solution: Given the two body effective potentials it performs the supersymmetric transformation in case where there are forbidden states to be removed. The three body wavefunction is expanded in hyperspherical coordinates, the hyper-angular part is a series of Jacobi polynomials and the hyper-radial part is written in terms of a Laguerre basis. Within this basis the three body matrix elements are calculated

  12. Low-potential iron-sulfur centers in photosystem I: an X-ray absorption spectroscopy study.

    PubMed

    McDermott, A E; Yachandra, V K; Guiles, R D; Britt, R D; Dexheimer, S L; Sauer, K; Klein, M P

    1988-05-31

    We have measured the X-ray absorption spectra of Fe in photosystem I (PS I) preparations from spinach and a thermophilic cyanobacterium, Synechococcus sp., to characterize structures of the Fe complexes that function as electron acceptors in PS I. These acceptors include centers A and B, which are probably typical [4Fe-4S] ferredoxins, and X. The structure of X is not known, but its electron paramagnetic resonance (EPR) spectrum has generated the suggestions that it is either a [2Fe-2S] or [4Fe-4S] ferredoxin or an Fe-quinone species. The iron X-ray absorption K-edge and iron extended X-ray absorption fine structure (EXAFS) spectra reveal that essentially all of the 11-14 Fe atoms present in the reaction center are present in the form of Fe-S centers and that not more than 1 atom out of 12 could be octahedral or oxygen-coordinated Fe. This suggests that, besides A and B, additional Fe-S clusters are present which are likely to be X. Our EXAFS spectra cannot be simulated adequately by a mixture of [4Fe-4S] ferredoxins with typical bond lengths and disorder parameters because the amplitude of Fe backscattering is small; however, excellent simulations of the data are consistent with a mixture of [2Fe-2S] ferredoxins and [4Fe-4S] ferredoxins, or with unusually distorted [4Fe-4S] clusters. We presume that the [2Fe-2S] or distorted [4Fe-4S] centers are X. The X-ray absorption spectra of PS I preparations from Synechococcus and spinach are essentially indistinguishable.

  13. A Phasin with Many Faces: Structural Insights on PhaP from Azotobacter sp. FA8

    PubMed Central

    Mezzina, Mariela P.; Wetzler, Diana E.; Catone, Mariela V.; Bucci, Hernan; Di Paola, Matias; Pettinari, M. Julia

    2014-01-01

    Phasins are a group of proteins associated to granules of polyhydroxyalkanoates (PHAs). Apart from their structural role as part of the PHA granule cover, different structural and regulatory functions have been found associated to many of them, and several biotechnological applications have been developed using phasin protein fusions. Despite their remarkable functional diversity, the structure of these proteins has not been analyzed except in very few studies. PhaP from Azotobacter sp. FA8 (PhaPAz) is a representative of the prevailing type in the multifunctional phasin protein family. Previous work performed in our laboratory using this protein have demonstrated that it has some very peculiar characteristics, such as its stress protecting effects in recombinant Escherichia coli, both in the presence and absence of PHA. The aim of the present work was to perform a structural characterization of this protein, to shed light on its properties. Its aminoacid composition revealed that it lacks clear hydrophobic domains, a characteristic that appears to be common to most phasins, despite their lipid granule binding capacity. The secondary structure of this protein, consisting of α-helices and disordered regions, has a remarkable capacity to change according to its environment. Several experimental data support that it is a tetramer, probably due to interactions between coiled-coil regions. These structural features have also been detected in other phasins, and may be related to their functional diversity. PMID:25077609

  14. Deflection-Based Structural Loads Estimation From the Active Aeroelastic Wing F/A-18 Aircraft

    NASA Technical Reports Server (NTRS)

    Lizotte, Andrew M.; Lokos, William A.

    2005-01-01

    Traditional techniques in structural load measurement entail the correlation of a known load with strain-gage output from the individual components of a structure or machine. The use of strain gages has proved successful and is considered the standard approach for load measurement. However, remotely measuring aerodynamic loads using deflection measurement systems to determine aeroelastic deformation as a substitute to strain gages may yield lower testing costs while improving aircraft performance through reduced instrumentation weight. This technique was examined using a reliable strain and structural deformation measurement system. The objective of this study was to explore the utility of a deflection-based load estimation, using the active aeroelastic wing F/A-18 aircraft. Calibration data from ground tests performed on the aircraft were used to derive left wing-root and wing-fold bending-moment and torque load equations based on strain gages, however, for this study, point deflections were used to derive deflection-based load equations. Comparisons between the strain-gage and deflection-based methods are presented. Flight data from the phase-1 active aeroelastic wing flight program were used to validate the deflection-based load estimation method. Flight validation revealed a strong bending-moment correlation and slightly weaker torque correlation. Development of current techniques, and future studies are discussed.

  15. Strain Gage Loads Calibration Testing of the Active Aeroelastic Wing F/A-18 Aircraft

    NASA Technical Reports Server (NTRS)

    Lokos, William A.; Olney, Candida D.; Chen, Tony; Crawford, Natalie D.; Stauf, Rick; Reichenbach, Eric Y.; Bessette, Denis (Technical Monitor)

    2002-01-01

    This report describes strain-gage calibration loading through the application of known loads of the Active Aeroelastic Wing F/A-18 airplane. The primary goal of this test is to produce a database suitable for deriving load equations for left and right wing root and fold shear; bending moment; torque; and all eight wing control-surface hinge moments. A secondary goal is to produce a database of wing deflections measured by string potentiometers and the onboard flight deflection measurement system. Another goal is to produce strain-gage data through both the laboratory data acquisition system and the onboard aircraft data system as a check of the aircraft system. Thirty-two hydraulic jacks have applied loads through whiffletrees to 104 tension-compression load pads bonded to the lower wing surfaces. The load pads covered approximately 60 percent of the lower wing surface. A series of 72 load cases has been performed, including single-point, double-point, and distributed load cases. Applied loads have reached 70 percent of the flight limit load. Maximum wingtip deflection has reached nearly 16 in.

  16. Inlet Flow Characteristics During Rapid Maneuvers for an F/A-18A Airplane

    NASA Technical Reports Server (NTRS)

    Steenken, William G.; Williams, John G.; Walsh, Kevin R.

    1999-01-01

    The F404-GE-400 engine powered F/A-18A High Alpha Research Vehicle (HARV) was used to examine the characteristics of inlet airflow during rapid aircraft maneuvers. A study of the degree of similarity between inlet data obtained during rapid aircraft maneuvers and inlet data obtained at steady aerodynamic attitudes was conducted at the maximum engine airflow of approximately 145 Ibm/sec using a computer model that was generated from inlet data obtained during steady aerodynamic maneuvers. Results show that rapid-maneuver inlet recoveries agreed very well with the recoveries obtained at equivalent stabilized angle-of-attack conditions. The peak dynamic circumferential distortion values obtained during rapid maneuvers agreed within 0.01 units of distortion over the 10 - 38 degree angle of attack range with the values obtained during steady aerodynamic maneuvers while similar agreement was found for the peak dynamic radial distortion values up to 29 degrees angle-of-attack. Exceedences of the rapid-maneuver peak dynamic circumferential distortion values relative to the peak distortion model values at steady attitudes occurred only at low or negative angles of attack and were inconsequential from an engine-stability assessment point of view. The results of this study validate the current industry practice of testing at steady aerodynamic conditions to characterize inlet recovery and peak dynamic distortion levels.

  17. Environmental embrittlement of iron-aluminide alloy FA-129 during gas tungsten arc welding

    SciTech Connect

    Fasching, A.A.; Edwards, G.R.; David, S.A.

    1994-12-31

    Iron aluminides are susceptible to hydrogen cold cracking during gastungsten arc welding (GTAW). Cracking occurs by brittle fracture in the fusion zone, which has been attributed to excessive grain growth during solidification. To further investigate hydrogen cold cracking in iron aluminides and, specifically, to study the effect of base material grain size on fusion zone cracking susceptibility, base materials of varying grain size were GTAW. The specimens for this investigation came from a production-sized vacuum arc remelt (VAR) ingot. The results of this investigation showed that changes in either the base material thermomechanical processing or the common welding parameters could not easily be used to refine the fusion zone grain size. This investigation showed that conventional GTAW produced coarse fusion zone grain structures even in fine-grained base material. The results also revealed that fracture strength decreased only slightly with a decrease in heat input, but exhibited a dramatic decrease as the water vapor content increased. in addition, the unrecrystallized base material showed the greatest susceptibility toward hydrogen cold cracking. Fracture stress versus grain size plots at different levels of water vapor were produced for iron-aluminide alloy FA-129.

  18. Papiliotrema siamense f.a., sp. nov., a yeast species isolated from plant leaves.

    PubMed

    Surussawadee, Janjira; Khunnamwong, Pannida; Srisuk, Nantana; Limtong, Savitree

    2014-09-01

    Two strains representing a novel species were isolated from the external surface of a sugar cane leaf (DMKU-SP85(T)) and tissue of a rice leaf (DMKU-RE97) collected in Thailand. On the basis of morphological, biochemical, physiological and chemotaxonomic characteristics, and sequence analysis of the D1/D2 region of the large subunit (LSU) rRNA gene and the internal transcribed spacer (ITS) region, the two strains were determined to represent a novel species of the genus Papiliotrema although sexual reproduction was not observed. The sequences of the D1/D2 region of the LSU rRNA gene and ITS region of the two strains were identical, but differed from those of the type strain of Cryptococcus nemorosus by 0.6 % nucleotide substitutions (four nucleotide substitutions out of 597 nucleotides) in the D1/D2 region of the LSU rRNA gene and 1.8 % nucleotide substitutions (nine nucleotide substitutions out of 499 nucleotides) in the ITS region. The name Papiliotrema siamense f.a., sp. nov. is proposed. The type strain is DMKU-SP85(T)( = BCC 69499(T) = CBS 13330(T)). PMID:24925598

  19. The aerodynamic characteristics of vortex ingestion for the F/A-18 inlet duct

    NASA Technical Reports Server (NTRS)

    Anderson, Bernhard H.

    1991-01-01

    A Reduced Navier-Stokes (RNS) solution technique was successfully combined with the concept of partitioned geometry and mesh generation to form a very efficient 3D RNS code aimed at the analysis-design engineering environment. Partitioned geometry and mesh generation is a pre-processor to augment existing geometry and grid generation programs which allows the solver to (1) recluster an existing gridlife mesh lattice, and (2) perturb an existing gridfile definition to alter the cross-sectional shape and inlet duct centerline distribution without returning to the external geometry and grid generator. The present results provide a quantitative validation of the initial value space marching 3D RNS procedure and demonstrates accurate predictions of the engine face flow field, with a separation present in the inlet duct as well as when vortex generators are installed to supress flow separation. The present results also demonstrate the ability of the 3D RNS procedure to analyze the flow physics associated with vortex ingestion in general geometry ducts such as the F/A-18 inlet. At the conditions investigated, these interactions are basically inviscid like, i.e., the dominant aerodynamic characteristics have their origin in inviscid flow theory.

  20. Induced Moment Effects of Formation Flight Using Two F/A-18 Aircraft

    NASA Technical Reports Server (NTRS)

    Hansen, Jennifer L.; Cobleigh, Brent R.

    2002-01-01

    Previous investigations into formation flight have shown the possibility for significant fuel savings through drag reduction. Using two F/A-18 aircraft, NASA Dryden Flight Research Center has investigated flying aircraft in autonomous formation. Positioning the trailing airplane for best drag reduction requires investigation of the wingtip vortex effects induced by the leading airplane. A full accounting of the vortex effect on the trailing airplane is desired to validate vortex-effect prediction methods and provide a database for the design of a formation flight autopilot. A recent flight phase has mapped the complete wingtip vortex effects at two flight conditions with the trailing airplane at varying distances behind the leading one. Force and moment data at Mach 0.56 and an altitude of 25,000 ft and Mach 0.86 and an altitude of 36,000 ft have been obtained with 20, 55, 110, and 190 ft of longitudinal distance between the aircraft. The moments induced by the vortex on the trailing airplane were well within the pilot's ability to control. This report discusses the data analysis methods and vortex-induced effects on moments and side force. An assessment of the impact of the nonlinear vortex effects on the design of a formation autopilot is offered.

  1. Spatial Characteristics of the Unsteady Differential Pressures on 16 percent F/A-18 Vertical Tails

    NASA Technical Reports Server (NTRS)

    Moses, Robert W.; Ashley, Holt

    1998-01-01

    Buffeting is an aeroelastic phenomenon which plagues high performance aircraft at high angles of attack. For the F/A-18 at high angles of attack, vortices emanating from wing/fuselage leading edge extensions burst, immersing the vertical tails in their turbulent wake. The resulting buffeting of the vertical tails is a concern from fatigue and inspection points of view. Previous flight and wind-tunnel investigations to determine the buffet loads on the tail did not provide a complete description of the spatial characteristics of the unsteady differential pressures. Consequently, the unsteady differential pressures were considered to be fully correlated in the analyses of buffet and buffeting. The use of fully correlated pressures in estimating the generalized aerodynamic forces for the analysis of buffeting yielded responses that exceeded those measured in flight and in the wind tunnel. To learn more about the spatial characteristics of the unsteady differential pressures, an available 16%, sting-mounted, F-18 wind-tunnel model was modified and tested in the Transonic Dynamics Tunnel (TDT) at the NASA Langley Research Center as part of the ACROBAT (Actively Controlled Response Of Buffet-Affected Tails) program. Surface pressures were measured at high angles of attack on flexible and rigid tails. Cross-correlation and cross-spectral analyses of the pressure time histories indicate that the unsteady differential pressures are not fully correlated. In fact, the unsteady differential pressure resemble a wave that travels along the tail. At constant angle of attack, the pressure correlation varies with flight speed.

  2. Twist Model Development and Results From the Active Aeroelastic Wing F/A-18 Aircraft

    NASA Technical Reports Server (NTRS)

    Lizotte, Andrew; Allen, Michael J.

    2005-01-01

    Understanding the wing twist of the active aeroelastic wing F/A-18 aircraft is a fundamental research objective for the program and offers numerous benefits. In order to clearly understand the wing flexibility characteristics, a model was created to predict real-time wing twist. A reliable twist model allows the prediction of twist for flight simulation, provides insight into aircraft performance uncertainties, and assists with computational fluid dynamic and aeroelastic issues. The left wing of the aircraft was heavily instrumented during the first phase of the active aeroelastic wing program allowing deflection data collection. Traditional data processing steps were taken to reduce flight data, and twist predictions were made using linear regression techniques. The model predictions determined a consistent linear relationship between the measured twist and aircraft parameters, such as surface positions and aircraft state variables. Error in the original model was reduced in some cases by using a dynamic pressure-based assumption and by using neural networks. These techniques produced excellent predictions for flight between the standard test points and accounted for nonlinearities in the data. This report discusses data processing techniques and twist prediction validation, and provides illustrative and quantitative results.

  3. Acoustic emission testing on an F/A-18 E/F titanium bulkhead

    NASA Astrophysics Data System (ADS)

    Martin, Christopher A.; Van Way, Craig B.; Lockyer, Allen J.; Kudva, Jayanth N.; Ziola, Steve M.

    1995-04-01

    An important opportunity recently transpired at Northrop Grumman Corporation to instrument an F/A - 18 E/F titanium bulkhead with broad band acoustic emission sensors during a scheduled structural fatigue test. The overall intention of this effort was to investigate the potential for detecting crack propagation using acoustic transmission signals for a large structural component. Key areas of experimentation and experience included (1) acoustic noise characterization, (2) separation of crack signals from extraneous noise, (3) source location accuracy, and (4) methods of acoustic transducer attachment. Fatigue cracking was observed and monitored by strategically placed acoustic emission sensors. The outcome of the testing indicated that accurate source location still remains enigmatic for non-specialist engineering personnel especially at this level of structural complexity. However, contrary to preconceived expectations, crack events could be readily separated from extraneous noise. A further dividend from the investigation materialized in the form of close correspondence between frequency domain waveforms of the bulkhead test specimen tested and earlier work with thick plates.

  4. Active Control of F/A-18 Vertical Tail Buffeting using Piezoelectric Actuators

    NASA Technical Reports Server (NTRS)

    Sheta, Essam F.; Moses, Robert W.; Huttsell, Lawerence J.; Harrand, Vincent J.

    2003-01-01

    Vertical tail buffeting is a serious multidisciplinary problem that limits the performance of twin-tail fighter aircraft. The buffet problem occurs at high angles of attack when the vortical flow breaks down ahead of the vertical tails resulting in unsteady and unbalanced pressure loads on the vertical tails. This paper describes a multidisciplinary computational investigation for buffet load alleviation of full F/A-18 aircraft using distributed piezoelectric actuators. The inboard and outboard surfaces of the vertical tail are equipped with piezoelectric actuators to control the buffet responses in the first bending and torsion modes. The electrodynamics of the smart structure are expressed with a three-dimensional finite element model. A single-input-single-output controller is designed to drive the active piezoelectric actuators. High-fidelity multidisciplinary analysis modules for the fluid dynamics, structure dynamics, electrodynamics of the piezoelectric actuators, fluid-structure interfacing, and grid motion are integrated into a multidisciplinary computing environment that controls the temporal synchronization of the analysis modules. Peak values of the power spectral density of tail tip acceleration are reduced by as much as 22% in the first bending mode and by as much as 82% in the first torsion mode. RMS values of tip acceleration are reduced by as much as 12%.

  5. F/A-18 forebody vortex control. Volume 2: Rotary-balance tests

    NASA Technical Reports Server (NTRS)

    Kramer, Brian R.; Suarez, Carlos J.; Malcolm, Gerald N.; Ayers, Bert F.

    1994-01-01

    A rotary-balance wind tunnel test was conducted on a six percent model of the F/A-18 at the NASA Ames 7 X 10-Foot Low Speed Wind Tunnel. The data reduction was specially written for the test in National Instruments' LabVIEW. The data acquisition, reduction and analysis was performed with a Macintosh computer. The primary objective of the test was to evaluate the effectiveness of several forebody vortex control configurations in a rotary flow field. The devices that were found to be the most effective during the static tests (Volume 1) were investigated and included both mechanical and pneumatic configurations. The mechanical systems evaluated were small, single and dual, rotating nose tip strakes and a vertical nose strake. The jet blowing configuration used nozzles canted inboard 60 degrees. A two segment tangential slot was also evaluated. The different techniques were evaluated at angles of attack of 30 degrees, 45 degrees, 51 degrees, and 60 degrees. Sideslip and Reynolds number were varied for some of the configurations. All of the techniques proved to be effective in the rotating flow field. The vertical nose strake had the largest 'envelope' of effectiveness. Forebody vortex control provides large, robust yawing moments at medium to high angles of attack, even during combat maneuvers such as loaded roll.

  6. Full-scale high angle-of-attack tests of an F/A-18

    NASA Technical Reports Server (NTRS)

    Meyn, Larry A.; Lanser, Wendy R.; James, Kevin D.

    1992-01-01

    This paper presents an overview of high angle-of-attack tests of a full-scale F/A-18 in the 80- by 120-Foot Wind Tunnel of the National Full-Scale Aerodynamic Complex at NASA Ames Research Center at Moffett Field, California. A production aircraft was tested over an angle-of-attack range of 18 to 50 deg and at wind speeds of up to 100 knots. These tests had three primary test objectives. Pneumatic and mechanical forebody flow control devices were tested at full-scale and shown to produce significant yawing moments for lateral control of the aircraft at high angles of attack. Mass flow requirements for the pneumatic system were found to scale with freestream density and speed rather than freestream dynamic pressure. Detailed measurements of the pressures buffeting the vertical tail were made and spatial variations in the buffeting frequency were found. The LEX fence was found to have a significant effect on the frequency distribution on the outboard surface of the vertical fin. In addition to the above measurements, an extensive set of data was acquired for the validation of computational fluid dynamics codes and for comparison with flight test and small-scale wind tunnel test results.

  7. Early-life study of the FA409 full-depth asphalt-concrete pavement sections

    SciTech Connect

    Hill, H.J.

    1988-01-01

    The Illinois Department of Transportation (IDOT) is currently implementing a mechanistic thickness-design procedure for full-depth asphalt-concrete pavements. This thesis is an early design-life investigation of full-depth asphalt-concrete pavements, constructed on FA409 near Carlyle, Illinois in 1986. Included in the study are: sampling and testing of paving and subgrade materials; extensive non-destructive testing (NDT) using the Falling Weight Deflectometer (FWD); development of techniques for interpreting NDT data; determination of as-built structural characteristics of the various pavement sections; evaluation of subsurface drainage and lime-treated soil behavior; and examination of the validity of the ILLI-PAVE computer model. The simplicity of a full-depth asphalt-concrete pavement allows useful information regarding pavement structure to be determined from FWD surface-deflection data. The ILLI-PAVE model was used in conjunction with statistical methods to quantify, in the form of regression equations or algorithms, the relationship between pavement structure (Tac, Eac, and Eri) and pavement response to FWD loading. Testing of pavement and subgrade material samples as used to validate these algorithms.

  8. Update: HFC 245fa Blown Foam Development with External Tank Spray Foams

    NASA Technical Reports Server (NTRS)

    Davis, S.

    2001-01-01

    The Marshall Space Flight Center (MSFC) Thermal Protection Systems (TPS) Materials Research Laboratory is currently investigating environmentally friendly blowing agents for use in the insulations of the Space Shuttle's External Tank. The original TPS foam materials of the External Tank were blown with chlorofluorocarbon 11, which is now regulated because of its high Ozone Depletion Potential (ODP). Hydrochlorofluorocarbons (HCFCs), with an ODP that is one tenth that of CFCs, have been widely adopted as an interim blowing agent in urethane insulations. In FY96, Lockheed Martin completed the production qualification and validation of HCFC 141b blown insulations. Because of the expected limited commercial lifetime of HCFC 141b, research efforts are underway to identify and develop alternatives with zero ODP. HFC245fa (1,1,1,3,3-pentaflouropropane) has been chosen by the manufacturer as a third-generation blowing agent to be marketed commercially. Preliminary work evaluating this third-generation candidate has demonstrated promising material mechanical property data. Favorable results from small-scale spray activities have justified evaluations using production foam processing spray parameters. With the scale-up of the spray equipment, however, additional processing issues have been identified. This paper will present data collected to date regarding the use of this blowing agent in External Tank spray foams.

  9. Aeroservoelastic Model Validation and Test Data Analysis of the F/A-18 Active Aeroelastic Wing

    NASA Technical Reports Server (NTRS)

    Brenner, Martin J.; Prazenica, Richard J.

    2003-01-01

    Model validation and flight test data analysis require careful consideration of the effects of uncertainty, noise, and nonlinearity. Uncertainty prevails in the data analysis techniques and results in a composite model uncertainty from unmodeled dynamics, assumptions and mechanics of the estimation procedures, noise, and nonlinearity. A fundamental requirement for reliable and robust model development is an attempt to account for each of these sources of error, in particular, for model validation, robust stability prediction, and flight control system development. This paper is concerned with data processing procedures for uncertainty reduction in model validation for stability estimation and nonlinear identification. F/A-18 Active Aeroelastic Wing (AAW) aircraft data is used to demonstrate signal representation effects on uncertain model development, stability estimation, and nonlinear identification. Data is decomposed using adaptive orthonormal best-basis and wavelet-basis signal decompositions for signal denoising into linear and nonlinear identification algorithms. Nonlinear identification from a wavelet-based Volterra kernel procedure is used to extract nonlinear dynamics from aeroelastic responses, and to assist model development and uncertainty reduction for model validation and stability prediction by removing a class of nonlinearity from the uncertainty.

  10. F/A-18 1/9th scale model tail buffet measurements

    NASA Technical Reports Server (NTRS)

    Martin, C. A.; Glaister, M. K.; Maclaren, L. D.; Meyn, L. A.; Ross, J.

    1991-01-01

    Wind tunnel tests were carried out on a 1/9th scale model of the F/A-18 at high angles of attack to investigate the characteristics of tail buffet due to bursting of the wing leading edge extension (LEX) vortices. The tests were carried out at the Aeronautical Research Laboratory low-speed wind tunnel facility and form part of a collaborative activity with NASA Ames Research Center, organized by The Technical Cooperative Program (TTCP). Information from the program will be used in the planning of similar collaborative tests, to be carried out at NASA Ames, on a full-scale aircraft. The program covered the measurement of unsteady pressures and fin vibration for cases with and without the wing LEX fences fitted. Fourier transform methods were used to analyze the unsteady data, and information on the spatial and temporal content of the vortex burst pressure field was obtained. Flow visualization of the vortex behavior was carried out using smoke and a laser light sheet technique.

  11. Adaptive Augmenting Control Flight Characterization Experiment on an F/A-18

    NASA Technical Reports Server (NTRS)

    VanZwieten, Tannen S.; Gilligan, Eric T.; Wall, John H.; Orr, Jeb S.; Miller, Christopher J.; Hanson, Curtis E.

    2014-01-01

    The NASA Marshall Space Flight Center (MSFC) Flight Mechanics and Analysis Division developed an Adaptive Augmenting Control (AAC) algorithm for launch vehicles that improves robustness and performance by adapting an otherwise welltuned classical control algorithm to unexpected environments or variations in vehicle dynamics. This AAC algorithm is currently part of the baseline design for the SLS Flight Control System (FCS), but prior to this series of research flights it was the only component of the autopilot design that had not been flight tested. The Space Launch System (SLS) flight software prototype, including the adaptive component, was recently tested on a piloted aircraft at Dryden Flight Research Center (DFRC) which has the capability to achieve a high level of dynamic similarity to a launch vehicle. Scenarios for the flight test campaign were designed specifically to evaluate the AAC algorithm to ensure that it is able to achieve the expected performance improvements with no adverse impacts in nominal or nearnominal scenarios. Having completed the recent series of flight characterization experiments on DFRC's F/A-18, the AAC algorithm's capability, robustness, and reproducibility, have been successfully demonstrated. Thus, the entire SLS control architecture has been successfully flight tested in a relevant environment. This has increased NASA's confidence that the autopilot design is ready to fly on the SLS Block I vehicle and will exceed the performance of previous architectures.

  12. Review of Full-Scale F/A-18 Research at NASA Ames Research Center

    NASA Technical Reports Server (NTRS)

    Olson, Lawrence E.; Schmitz, Fredric H. (Technical Monitor)

    1994-01-01

    Results of flow visualization and tail buffett studies conducted on a full-scale production F/A-18 fighter aircraft in the 80- by 120-Foot Wind Tunnel of the National Full-Scale Aerodynamic Complex are presented. Test conditions range between 20 degrees and 40 degrees angle of attack, 16 degrees and -16 degrees side-slip angle, and up to a Mach number of 0.15 (corresponding to a Reynolds number of 12.3 x 10(exp 6) based on mean aerodynamic chord). Flow visualization results include both surface and off-surface techniques that examine forebody, canopy, leading-edge extension, and wing flow fields. Unsteady pressures measured at 96 locations on the port tail fin are used to determine the effect of a removable leading-edge extension fence on tail buffet loads at high angle of attack. Analyses and comparisons include tail fin bending moment and wave velocities on the tail surface. Repeatability and scaling issues are assessed through comparison with measurements from previous full-scale tests and several small-scales tests.

  13. Functional characterization of FaNIP1;1 gene, a ripening-related and receptacle-specific aquaporin in strawberry fruit.

    PubMed

    Molina-Hidalgo, Francisco J; Medina-Puche, Laura; Gelis, Samuel; Ramos, José; Sabir, Farzana; Soveral, Graça; Prista, Catarina; Iglesias-Fernández, Raquel; Caballero, José L; Muñoz-Blanco, Juan; Blanco-Portales, Rosario

    2015-09-01

    Strawberry fruit (Fragaria × ananassa) is a soft fruit with high water content at ripe stage (more than 90% of its fresh weight). Aquaporins play an important role in plant water homeostasis, through the facilitation of water transport and solutes. We report the role played by FaNIP1;1 in the receptacle ripening process. The analysis by qRT-PCR of FaNIP1;1 showed that this gene is mainly expressed in fruit receptacle and has a ripening-related expression pattern that was accompanied by an increase in both the abscisic acid and water content of the receptacle throughout fruit ripening. Moreover, FaNIP1;1 was induced in situations of water deficit. Additionally, we show that FaNIP1;1 expression was positively regulated by abscisic acid and negatively regulated by auxins. The water transport capacity of FaNIP1;1 was determined by a stopped-flow spectroscopy in yeast over-expressing FaNIP1;1. Glycerol, H2O2 and boron transport were also demonstrated in yeast. On the other hand, GFP-FaNIP1;1 fusion protein was located in plasma membrane. In conclusion, FaNIP1;1 seems to play an important role increasing the plasma membrane permeability, that allows the water accumulation in the strawberry fruit receptacle throughout the ripening process. PMID:26259188

  14. Characterization of a chromosomal type II toxin-antitoxin system mazEaFa in the Cyanobacterium Anabaena sp. PCC 7120.

    PubMed

    Ning, Degang; Jiang, Yan; Liu, Zhaoying; Xu, Qinggang

    2013-01-01

    Cyanobacteria have evolved to survive stressful environmental changes by regulating growth, however, the underlying mechanism for this is obscure. The ability of chromosomal type II toxin-antitoxin (TA) systems to modulate growth or cell death has been documented in a variety of prokaryotes. A chromosomal mazEaFa locus of Anabaena sp. PCC 7120 has been predicted as a putative mazEF TA system. Here we demonstrate that mazEaFa form a bicistronic operon that is co-transcribed under normal growth conditions. Overproduction of MazFa induced Anabaena growth arrest which could be neutralized by co-expression of MazEa. MazFa also inhibited the growth of Escherichia coli cells, and this effect could be overcome by simultaneous or subsequent expression of MazEa via formation of the MazEa-MazFa complex in vivo, further confirming the nature of the mazEaFa locus as a type II TA system. Interestingly, like most TA systems, deletion of mazEaFa had no effect on the growth of Anabaena during the tested stresses. Our data suggest that mazEaFa, or together with other chromosomal type II TA systems, may promote cells to cope with particular stresses by inducing reversible growth arrest of Anabaena.

  15. Functional characterization of FaNIP1;1 gene, a ripening-related and receptacle-specific aquaporin in strawberry fruit.

    PubMed

    Molina-Hidalgo, Francisco J; Medina-Puche, Laura; Gelis, Samuel; Ramos, José; Sabir, Farzana; Soveral, Graça; Prista, Catarina; Iglesias-Fernández, Raquel; Caballero, José L; Muñoz-Blanco, Juan; Blanco-Portales, Rosario

    2015-09-01

    Strawberry fruit (Fragaria × ananassa) is a soft fruit with high water content at ripe stage (more than 90% of its fresh weight). Aquaporins play an important role in plant water homeostasis, through the facilitation of water transport and solutes. We report the role played by FaNIP1;1 in the receptacle ripening process. The analysis by qRT-PCR of FaNIP1;1 showed that this gene is mainly expressed in fruit receptacle and has a ripening-related expression pattern that was accompanied by an increase in both the abscisic acid and water content of the receptacle throughout fruit ripening. Moreover, FaNIP1;1 was induced in situations of water deficit. Additionally, we show that FaNIP1;1 expression was positively regulated by abscisic acid and negatively regulated by auxins. The water transport capacity of FaNIP1;1 was determined by a stopped-flow spectroscopy in yeast over-expressing FaNIP1;1. Glycerol, H2O2 and boron transport were also demonstrated in yeast. On the other hand, GFP-FaNIP1;1 fusion protein was located in plasma membrane. In conclusion, FaNIP1;1 seems to play an important role increasing the plasma membrane permeability, that allows the water accumulation in the strawberry fruit receptacle throughout the ripening process.

  16. GLUCOMANNAN AND GLUCOMANNAN PLUS SPIRULINA-ENRICHED SQUID-SURIMI ADDED TO HIGH SATURATED DIET AFFECT GLYCEMIA, PLASMA AND ADIPOSE LEPTIN AND ADIPONECTIN LEVELS IN GROWING FA/FA RATS.

    PubMed

    Vázquez-Velasco, Miguel; González-Torres, Laura; Méndez, María Teresa; Bastida, Sara; Benedí, Juana; González-Muñoz, M José; Sánchez-Muniz, Francisco J

    2015-12-01

    Type 2 diabetes is a very prevalent chronic disease. Among dietary factors for its prevention and treatment, interest has grown in satiating fibre (konjac glucomannan) and spirulina. Our previous studies suggest that glucomannan itself and/or in conjunction to spirulina displayed hypolipemic and antioxidant effects when incorporated to squid surimi as functional ingredients. The present study aims to determine whether glucomannan- enriched or glucomannan plus spirulina-enriched squid-surimi improve plasma glucose and insulin levels in Zucker fa/fa rats fed a high saturated fat diet. Twenty four growing rats, divided into three groups, were given modified AIN-93M diets for seven weeks: 30% squid-surimi control diet (C), 30% glucomannan-enriched squid-surimi diet (G) and 30% glucomannan plus spirulina-enriched squid-surimi diet (GS). All rats became hyperglycemics and hyperinsulinemics, but G and GS diets induced significantly lower glucose levels (20%; p < 0.05) but did not modify insulinemia with respect to C diet. GS animals showed higher HOMA-D (p < 0.05) than C ones suggesting increased insulin availability. Plasma leptin and adiponectin decreased in G and GS vs. C group (p < 0.05). Adipose adiponectin increased significantly in G and GS vs. C rats (16-20 times, p < 0.01). Leptin in adipose tissue was higher in GS vs. G group (p < 0.05). In conclusion, both glucomannan-diets were able to reduce hyperglycemia and increase adipose tissue adiponectin levels in fa/fa rats, suggesting an anti-hypertrophic and insulin-sensitizing adipokine effect in this tissue. Spirulina inclusion increased insulin availability. Although results are promising, the utility of consuming glucomannan surimis as part of usual diets demands future studies.

  17. GLUCOMANNAN AND GLUCOMANNAN PLUS SPIRULINA-ENRICHED SQUID-SURIMI ADDED TO HIGH SATURATED DIET AFFECT GLYCEMIA, PLASMA AND ADIPOSE LEPTIN AND ADIPONECTIN LEVELS IN GROWING FA/FA RATS.

    PubMed

    Vázquez-Velasco, Miguel; González-Torres, Laura; Méndez, María Teresa; Bastida, Sara; Benedí, Juana; González-Muñoz, M José; Sánchez-Muniz, Francisco J

    2015-01-01

    Type 2 diabetes is a very prevalent chronic disease. Among dietary factors for its prevention and treatment, interest has grown in satiating fibre (konjac glucomannan) and spirulina. Our previous studies suggest that glucomannan itself and/or in conjunction to spirulina displayed hypolipemic and antioxidant effects when incorporated to squid surimi as functional ingredients. The present study aims to determine whether glucomannan- enriched or glucomannan plus spirulina-enriched squid-surimi improve plasma glucose and insulin levels in Zucker fa/fa rats fed a high saturated fat diet. Twenty four growing rats, divided into three groups, were given modified AIN-93M diets for seven weeks: 30% squid-surimi control diet (C), 30% glucomannan-enriched squid-surimi diet (G) and 30% glucomannan plus spirulina-enriched squid-surimi diet (GS). All rats became hyperglycemics and hyperinsulinemics, but G and GS diets induced significantly lower glucose levels (20%; p < 0.05) but did not modify insulinemia with respect to C diet. GS animals showed higher HOMA-D (p < 0.05) than C ones suggesting increased insulin availability. Plasma leptin and adiponectin decreased in G and GS vs. C group (p < 0.05). Adipose adiponectin increased significantly in G and GS vs. C rats (16-20 times, p < 0.01). Leptin in adipose tissue was higher in GS vs. G group (p < 0.05). In conclusion, both glucomannan-diets were able to reduce hyperglycemia and increase adipose tissue adiponectin levels in fa/fa rats, suggesting an anti-hypertrophic and insulin-sensitizing adipokine effect in this tissue. Spirulina inclusion increased insulin availability. Although results are promising, the utility of consuming glucomannan surimis as part of usual diets demands future studies. PMID:26667726

  18. Interaction of PqqE and PqqD in the pyrroloquinoline quinone (PQQ) biosynthetic pathway links PqqD to the radical SAM superfamily.

    PubMed

    Wecksler, Stephen R; Stoll, Stefan; Iavarone, Anthony T; Imsand, Erin M; Tran, Ha; Britt, R David; Klinman, Judith P

    2010-10-01

    pqqD is one of six genes required for PQQ production in Klebsiella pneumoniae. Herein, we demonstrate that PqqD interacts specifically with the radical SAM enzyme PqqE, causing a perturbation in the electronic environment around the [4Fe-4S](+) clusters. This interaction redirects the role for PqqD in PQQ biosynthesis.

  19. Organometallic Complex Formed by an Unconventional Radical S-Adenosylmethionine Enzyme.

    PubMed

    Dong, Min; Horitani, Masaki; Dzikovski, Boris; Pandelia, Maria-Eirini; Krebs, Carsten; Freed, Jack H; Hoffman, Brian M; Lin, Hening

    2016-08-10

    Pyrococcus horikoshii Dph2 (PhDph2) is an unusual radical S-adenosylmethionine (SAM) enzyme involved in the first step of diphthamide biosynthesis. It catalyzes the reaction by cleaving SAM to generate a 3-amino-3-carboxypropyl (ACP) radical. To probe the reaction mechanism, we synthesized a SAM analogue (SAMCA), in which the ACP group of SAM is replaced with a 3-carboxyallyl group. SAMCA is cleaved by PhDph2, yielding a paramagnetic (S = 1/2) species, which is assigned to a complex formed between the reaction product, α-sulfinyl-3-butenoic acid, and the [4Fe-4S] cluster. Electron-nuclear double resonance (ENDOR) measurements with (13)C and (2)H isotopically labeled SAMCA support a π-complex between the C═C double bond of α-sulfinyl-3-butenoic acid and the unique iron of the [4Fe-4S] cluster. This is the first example of a radical SAM-related [4Fe-4S](+) cluster forming an organometallic complex with an alkene, shedding additional light on the mechanism of PhDph2 and expanding our current notions for the reactivity of [4Fe-4S] clusters in radical SAM enzymes. PMID:27465315

  20. Transonic Unsteady Aerodynamics of the F/A-18E at Conditions Promoting Abrupt Wing Stall

    NASA Technical Reports Server (NTRS)

    Schuster, David M.; Byrd, James E.

    2003-01-01

    A transonic wind tunnel test of an 8% F/A-18E model was conducted in the NASA Langley Research Center (LaRC) 16-Foot Transonic Tunnel (16-Ft TT) to investigate the Abrupt Wing Stall (AWS) characteristics of this aircraft. During this test, both steady and unsteady measurements of balance loads, wing surface pressures, wing root bending moments, and outer wing accelerations were performed. The test was conducted with a wide range of model configurations and test conditions in an attempt to reproduce behavior indicative of the AWS phenomenon experienced on full-scale aircraft during flight tests. This paper focuses on the analysis of the unsteady data acquired during this test. Though the test apparatus was designed to be effectively rigid. model motions due to sting and balance flexibility were observed during the testing, particularly when the model was operating in the AWS flight regime. Correlation between observed aerodynamic frequencies and model structural frequencies are analyzed and presented. Significant shock motion and separated flow is observed as the aircraft pitches through the AWS region. A shock tracking strategy has been formulated to observe this phenomenon. Using this technique, the range of shock motion is readily determined as the aircraft encounters AWS conditions. Spectral analysis of the shock motion shows the frequencies at which the shock oscillates in the AWS region, and probability density function analysis of the shock location shows the propensity of the shock to take on a bi-stable and even tri-stable character in the AWS flight regime.

  1. Navier-Stokes, flight, and wind tunnel flow analysis for the F/A-18 aircraft

    NASA Technical Reports Server (NTRS)

    Ghaffari, Farhad

    1994-01-01

    Computational analysis of flow over the F/A-18 aircraft is presented along with complementary data from both flight and wind tunnel experiments. The computational results are based on the three-dimensional thin-layer Navier-Stokes formulation and are obtained from an accurate surface representation of the fuselage, leading-edge extension (LEX), and the wing geometry. However, the constraints imposed by either the flow solver and/or the complexity associated with the flow-field grid generation required certain geometrical approximations to be implemented in the present numerical model. In particular, such constraints inspired the removal of the empennage and the blocking (fairing) of the inlet face. The results are computed for three different free-stream flow conditions and compared with flight test data of surface pressure coefficients, surface tuft flow, and off-surface vortical flow characteristics that included breakdown phenomena. Excellent surface pressure coefficient correlations, both in terms of magnitude and overall trend, are obtained on the forebody throughout the range of flow conditions. Reasonable pressure agreement was obtained over the LEX; the general correlation tends to improve at higher angles of attack. The surface tuft flow and the off-surface vortex flow structures compared qualitatively well with the flight test results. To evaluate the computational results, a wind tunnel investigation was conducted to determine the effects of existing configurational differences between the flight vehicle and the numerical model on aerodynamic characteristics. In most cases, the geometrical approximations made to the numerical model had very little effect on overall aerodynamic characteristics.

  2. Design and development of an F/A-18 inlet distortion rake: A cost and time saving solution

    NASA Technical Reports Server (NTRS)

    Yuhas, Andrew J.; Ray, Ronald J.; Burley, Richard R.; Steenken, William G.; Lechtenberg, Leon; Thornton, Don

    1995-01-01

    An innovative inlet total pressure distortion measurement rake has been designed and developed for the F/A-18 A/B/C/D aircraft inlet. The design was conceived by NASA and General Electric Aircraft Engines personnel. This rake has been flight qualified and flown in the F/A-18 High Alpha Research Vehicle at NASA Dryden Flight Research Center, Edwards, California. The eight-legged, one-piece, wagon wheel design of the rake was developed at a reduced cost and offered reduced installation time compared to traditional designs. The rake features 40 dual-measurement ports for low- and high-frequency pressure measurements with the high-frequency transducer mounted at the port. This high-frequency transducer offers direct absolute pressure measurements from low to high frequencies of interest, thereby allowing the rake to be used during highly dynamic aircraft maneuvers. Outstanding structural characteristics are inherent to the design through its construction and use of lightweight materials.

  3. Crystallization and electron paramagnetic resonance characterization of the complex of photosystem I with its natural electron acceptor ferredoxin.

    PubMed Central

    Fromme, Petra; Bottin, Hervé; Krauss, Norbert; Sétif, Pierre

    2002-01-01

    The formation of a transient complex between photosystem I and ferredoxin is involved in the process of ferredoxin photoreduction in oxygenic photosynthetic organisms. Reduced ferredoxin is an essential redox intermediate involved in many assimilatory processes and is necessary for the reduction of NADP(+) to NADPH. Single crystals from a complex of photosystem I with ferredoxin were grown using PEG 400 and CaCl(2) as precipitation agents. The crystals diffract x-rays to a resolution of 7-8 A. The space group was determined to be orthorhombic with the unit cell dimensions a = 194 A, b = 208 A, and c = 354 A. The crystals contain photosystem I and ferredoxin in a 1:1 ratio. Electron paramagnetic resonance (EPR) measurements on these crystals are reported, where EPR signals of the three [4Fe-4S] clusters F(A), F(B), F(X), and the [2Fe-2S] cluster of ferredoxin were detected. From the EPR spectra observed at three particular orientations of the crystal in the magnetic field, the full orientation pattern of the F g-tensor was simulated. This simulation is consistent with the presence of 12 magnetically inequivalent F clusters per unit cell with the C(3) axis of the PSI trimers oriented at (23 degrees, 72 degrees, 77 degrees ) to the unit cell axes. PMID:12324399

  4. An H-Infinity Approach to Control Synthesis with Load Minimization for the F/A-18 Active Aeroelastic Wing

    NASA Technical Reports Server (NTRS)

    Lind, Rick

    1999-01-01

    The F/A-18 Active Aeroelastic Wing research aircraft will demonstrate technologies related to aeroservoelastic effects such as wing twist and load minimization. This program presents several challenges for control design that are often not considered for traditional aircraft. This paper presents a control design based on H-infinity synthesis that simultaneously considers the multiple objectives associated with handling qualities, actuator limitations, and loads. A point design is presented to demonstrate a controller and the resulting closed-loop properties.

  5. Natural abundance stable carbon isotope evidence for the routing and de novo synthesis of bone FA and cholesterol.

    PubMed

    Jim, Susan; Ambrose, Stanley H; Evershed, Richard P

    2003-02-01

    This research reported in this paper investigated the relationship between diet and bone FA and cholesterol in rats raised on a variety of isotopically controlled diets comprising 20% C3 or C4 protein (casein) and C3 and/or C4 nonprotein or energy (sucrose, starch, and oil) macronutrients. Compound-specific stable carbon isotope analysis (delta13C) was performed on the FA (16:0, 18:0, 18:1, and 18:2) and cholesterol isolated from the diet (n = 4) and bone (n = 8) of these animals. The dietary signals reflected by the bone lipids were investigated using linear regression analysis. delta13C values of bone cholesterol and stearic (18:0) acid were shown to reflect whole-diet delta13C values, whereas the delta13C values of bone palmitic (16:0), oleic (18:1), and linoleic (18:2) acids reflected dietary FA delta13C values. Dietary signal differences are a result of the balance between direct incorporation (or routing) and de novo synthesis of each of these bone lipids. Estimates of the degree of routing of these bone lipids gleaned from correlations between delta13C(dlipid-wdiet) (= delta13C(diet lipid) - delta13C(whole diet)) spacings and delta13C(blipid-wdiet) (= delta13C(bone lipid) - delta13C(whole diet)) fractionations demonstrated that the extent of routing, where 18:2 > 16:0 > 18:1 > 18:0 > cholesterol, reflected the relative abundances of these lipids in the diet. These findings provide the basis for more accurate insights into diet when the delta13C analysis of bone fatty FA or cholesterol is employed.

  6. Smoke generators show the twisting paths of wingtip vortices behind two NASA Dryden F/A-18 jets used

    NASA Technical Reports Server (NTRS)

    2001-01-01

    Smoke generators show the twisting paths of wingtip vortices behind two NASA Dryden F/A-18 jets used in the Autonomous Formation Flight (AFF) program. A vortex is a spiraling current of air emanating from aircraft wingtips as they fly. By mapping the vortex pattern and using sophisticated software to put the trailing aircraft in the optimum location, the energy of the vortex could result in fuel savings for the follower aircraft of 15 percent or more.

  7. A NASA F/A-18, participating in the Automated Aerial Refueling (AAR) project, flies over the Dryden

    NASA Technical Reports Server (NTRS)

    2002-01-01

    A NASA F/A-18 flies over the Dryden Flight Research Center and Rogers Dry Lake on December 11, 2002. The aircraft is participating in the Automated Aerial Refueling (AAR) project. The 300-gallon aerial refueling store seen on the belly of the aircraft carries fuel and a refueling drogue. This aircraft acts as a tanker in the study to develop an aerodynamic model for future automated aerial refueling, especially of unmanned vehicles.

  8. Fluorophore Absorption Size Exclusion Chromatography (FA-SEC): An Alternative Method for High-Throughput Detergent Screening of Membrane Proteins.

    PubMed

    Lin, Sung-Yao; Sun, Xing-Han; Hsiao, Yu-Hsuan; Chang, Shao-En; Li, Guan-Syun; Hu, Nien-Jen

    2016-01-01

    Membrane proteins play key roles in many fundamental functions in cells including ATP synthesis, ion and molecule transporter, cell signalling and enzymatic reactions, accounting for ~30% genes of whole genomes. However, the hydrophobic nature of membrane proteins frequently hampers the progress of structure determination. Detergent screening is the critical step in obtaining stable detergent-solubilized membrane proteins and well-diffracting protein crystals. Fluorescence Detection Size Exclusion Chromatography (FSEC) has been developed to monitor the extraction efficiency and monodispersity of membrane proteins in detergent micelles. By tracing the FSEC profiles of GFP-fused membrane proteins, this method significantly enhances the throughput of detergent screening. However, current methods to acquire FSEC profiles require either an in-line fluorescence detector with the SEC equipment or an off-line spectrofluorometer microplate reader. Here, we introduce an alternative method detecting the absorption of GFP (FA-SEC) at 485 nm, thus making this methodology possible on conventional SEC equipment through the in-line absorbance spectrometer. The results demonstrate that absorption is in great correlation with fluorescence of GFP. The comparably weaker absorption signal can be improved by using a longer path-length flow cell. The FA-SEC profiles were congruent with the ones plotted by FSEC, suggesting FA-SEC could be a comparable and economical setup for detergent screening of membrane proteins. PMID:27332877

  9. Active Aeroelastic Wing Aerodynamic Model Development and Validation for a Modified F/A-18A Airplane

    NASA Technical Reports Server (NTRS)

    Cumming, Stephen B.; Diebler, Corey G.

    2005-01-01

    A new aerodynamic model has been developed and validated for a modified F/A-18A airplane used for the Active Aeroelastic Wing (AAW) research program. The goal of the program was to demonstrate the advantages of using the inherent flexibility of an aircraft to enhance its performance. The research airplane was an F/A-18A with wings modified to reduce stiffness and a new control system to increase control authority. There have been two flight phases. Data gathered from the first flight phase were used to create the new aerodynamic model. A maximum-likelihood output-error parameter estimation technique was used to obtain stability and control derivatives. The derivatives were incorporated into the National Aeronautics and Space Administration F-18 simulation, validated, and used to develop new AAW control laws. The second phase of flights was used to evaluate the handling qualities of the AAW airplane and the control law design process, and to further test the accuracy of the new model. The flight test envelope covered Mach numbers between 0.85 and 1.30 and dynamic pressures from 600 to 1250 pound-force per square foot. The results presented in this report demonstrate that a thorough parameter identification analysis can be used to improve upon models that were developed using other means. This report describes the parameter estimation technique used, details the validation techniques, discusses differences between previously existing F/A-18 models, and presents results from the second phase of research flights.

  10. A water tunnel flow visualization study of the vortex flow structures on the F/A-18 aircraft

    NASA Technical Reports Server (NTRS)

    Sandlin, Doral R.; Ramirez, Edgar J.

    1991-01-01

    The vortex flow structures occurring on the F/A-18 aircraft at high angles of attack were studied. A water tunnel was used to gather flow visualization data on the forebody vortex and the wing leading edge extension vortex. The longitudinal location of breakdown of the leading edge vortex was found to be consistently dependent on the angle of attack. Other parameters such as Reynolds number, model scale, and model fidelity had little influence on the overall behavior of the flow structures studied. The lateral location of the forebody vortex system was greatly influenced by changes in the angle of sideslip. Strong interactions can occur between the leading edge extension vortex and the forebody vortex. Close attention was paid to vortex induced flows on various airframe components of the F/A-18. Reynolds number and angle of attack greatly affected the swirling intensity, and therefore the strength of the studied vortices. Water tunnel results on the F/A-18 correlated well with those obtained in similar studies at both full and sub scale levels. The water tunnel can provide, under certain conditions, good simulations of realistic flows in full scale configurations.

  11. Fluorophore Absorption Size Exclusion Chromatography (FA-SEC): An Alternative Method for High-Throughput Detergent Screening of Membrane Proteins.

    PubMed

    Lin, Sung-Yao; Sun, Xing-Han; Hsiao, Yu-Hsuan; Chang, Shao-En; Li, Guan-Syun; Hu, Nien-Jen

    2016-01-01

    Membrane proteins play key roles in many fundamental functions in cells including ATP synthesis, ion and molecule transporter, cell signalling and enzymatic reactions, accounting for ~30% genes of whole genomes. However, the hydrophobic nature of membrane proteins frequently hampers the progress of structure determination. Detergent screening is the critical step in obtaining stable detergent-solubilized membrane proteins and well-diffracting protein crystals. Fluorescence Detection Size Exclusion Chromatography (FSEC) has been developed to monitor the extraction efficiency and monodispersity of membrane proteins in detergent micelles. By tracing the FSEC profiles of GFP-fused membrane proteins, this method significantly enhances the throughput of detergent screening. However, current methods to acquire FSEC profiles require either an in-line fluorescence detector with the SEC equipment or an off-line spectrofluorometer microplate reader. Here, we introduce an alternative method detecting the absorption of GFP (FA-SEC) at 485 nm, thus making this methodology possible on conventional SEC equipment through the in-line absorbance spectrometer. The results demonstrate that absorption is in great correlation with fluorescence of GFP. The comparably weaker absorption signal can be improved by using a longer path-length flow cell. The FA-SEC profiles were congruent with the ones plotted by FSEC, suggesting FA-SEC could be a comparable and economical setup for detergent screening of membrane proteins.

  12. PREFACE: Nuclear Cluster Conference; Cluster'07

    NASA Astrophysics Data System (ADS)

    Freer, Martin

    2008-05-01

    The Cluster Conference is a long-running conference series dating back to the 1960's, the first being initiated by Wildermuth in Bochum, Germany, in 1969. The most recent meeting was held in Nara, Japan, in 2003, and in 2007 the 9th Cluster Conference was held in Stratford-upon-Avon, UK. As the name suggests the town of Stratford lies upon the River Avon, and shortly before the conference, due to unprecedented rainfall in the area (approximately 10 cm within half a day), lay in the River Avon! Stratford is the birthplace of the `Bard of Avon' William Shakespeare, and this formed an intriguing conference backdrop. The meeting was attended by some 90 delegates and the programme contained 65 70 oral presentations, and was opened by a historical perspective presented by Professor Brink (Oxford) and closed by Professor Horiuchi (RCNP) with an overview of the conference and future perspectives. In between, the conference covered aspects of clustering in exotic nuclei (both neutron and proton-rich), molecular structures in which valence neutrons are exchanged between cluster cores, condensates in nuclei, neutron-clusters, superheavy nuclei, clusters in nuclear astrophysical processes and exotic cluster decays such as 2p and ternary cluster decay. The field of nuclear clustering has become strongly influenced by the physics of radioactive beam facilities (reflected in the programme), and by the excitement that clustering may have an important impact on the structure of nuclei at the neutron drip-line. It was clear that since Nara the field had progressed substantially and that new themes had emerged and others had crystallized. Two particular topics resonated strongly condensates and nuclear molecules. These topics are thus likely to be central in the next cluster conference which will be held in 2011 in the Hungarian city of Debrechen. Martin Freer Participants and Cluster'07

  13. High-altitude searches for vulcanoids: Observations from F/A-18B aircraft

    NASA Astrophysics Data System (ADS)

    Durda, D. D.; Stern, S. A.

    2003-05-01

    We have conducted a high-altitude observing campaign to search for vulcanoids, a population of small, asteroid-like bodies hypothesized to reside in the dynamically stable region interior to Mercury's orbit (i.e., orbits with aphelia <0.21 AU). This airborne search campaign utilized our versatile and highly capable SWUIS-A (Southwest Universal Imaging System - Airborne) instrument flown with SwRI flight astronomers to an altitude of 49,000 ft MSL aboard NASA F/A-18B aircraft in order to obtain darker twilight conditions for near-Sun observing than are possible from the ground. The first observing run (3 nights) was successfully completed at NASA's Dryden Flight Research Center during the March/April 2002 vernal equinox observing opportunity; the second observing run (3 nights) was completed during the September 2002 autumnal equinox observing opportunity. On each of the three evening and three morning twilight flights we recorded image data covering 250 square degrees of sky centered on the ecliptic from solar elongations of 6-18 deg. Reduction of the Mar/Apr and Sep 2002 data sets demonstrates that we are reliably detecting objects to magnitude V = 9.5-11 at 15-20 degrees solar elongation. This is significantly fainter than the instrument would have performed from the ground and comparable to the faintest stars visible in our space-based SOHO LASCO C3 coronagraph vulcanoids search (Durda et al. 2000; Icarus 148, 312-315). The SWUIS-A instrument itself is capable of imaging objects as faint as magnitude V = 13, corresponding to vulcanoids less than 10 km across, with a sufficiently dark sky background. For reference, V = 10 corresponds to a 18-km diameter object 1 AU from Earth and 0.15 AU from the sun with a Mercury-like geometric albedo of 14%. No vulcanoid candidates have been detected in the 49,000-ft altitude airborne observations to date. We thank NASA research pilots Rick Searfoss, Frank Batteas, Craig Bomben, and Dana Purifoy. This research is supported by

  14. Survey on granularity clustering.

    PubMed

    Ding, Shifei; Du, Mingjing; Zhu, Hong

    2015-12-01

    With the rapid development of uncertain artificial intelligent and the arrival of big data era, conventional clustering analysis and granular computing fail to satisfy the requirements of intelligent information processing in this new case. There is the essential relationship between granular computing and clustering analysis, so some researchers try to combine granular computing with clustering analysis. In the idea of granularity, the researchers expand the researches in clustering analysis and look for the best clustering results with the help of the basic theories and methods of granular computing. Granularity clustering method which is proposed and studied has attracted more and more attention. This paper firstly summarizes the background of granularity clustering and the intrinsic connection between granular computing and clustering analysis, and then mainly reviews the research status and various methods of granularity clustering. Finally, we analyze existing problem and propose further research.

  15. Cluster automorphism groups of cluster algebras with coefficients

    NASA Astrophysics Data System (ADS)

    Chang, Wen; Zhu, Bin

    2016-10-01

    We study the cluster automorphism group of a skew-symmetric cluster algebra with geometric coefficients. For this, we introduce the notion of gluing free cluster algebra, and show that under a weak condition the cluster automorphism group of a gluing free cluster algebra is a subgroup of the cluster automorphism group of its principal part cluster algebra (i.e. the corresponding cluster algebra without coefficients). We show that several classes of cluster algebras with coefficients are gluing free, for example, cluster algebras with principal coefficients, cluster algebras with universal geometric coefficients, and cluster algebras from surfaces (except a 4-gon) with coefficients from boundaries. Moreover, except four kinds of surfaces, the cluster automorphism group of a cluster algebra from a surface with coefficients from boundaries is isomorphic to the cluster automorphism group of its principal part cluster algebra; for a cluster algebra with principal coefficients, its cluster automorphism group is isomorphic to the automorphism group of its initial quiver.

  16. With a long flight data probe extending from its nose, this F/A-18A has been modified to conduct fli

    NASA Technical Reports Server (NTRS)

    2001-01-01

    With a long flight data probe extending from its nose, this F/A-18A has been modified to conduct flight research in the Active Aeroelastic Wing (AAW) project at NASA's Dryden Flight Research Center, Edwards, California.

  17. A modified F/A-18A sporting a distinctive red, white and blue paint scheme is the test aircraft for

    NASA Technical Reports Server (NTRS)

    2001-01-01

    A modified F/A-18A sporting a distinctive red, white and blue paint scheme is the test aircraft for the Active Aeroelastic Wing (AAW) project at NASA's Dryden Flight Research Center, Edwards, California.

  18. This modified F/A-18A with its distinctive red, white and blue paint scheme is the test aircraft for

    NASA Technical Reports Server (NTRS)

    2001-01-01

    This modified F/A-18A with its distinctive red, white and blue paint scheme is the test aircraft for the Active Aeroelastic Wing (AAW) project at NASA's Dryden Flight Research Center, Edwards, California.

  19. GNRs@SiO₂-FA in combination with radiotherapy induces the apoptosis of HepG2 cells by modulating the expression of apoptosis-related proteins.

    PubMed

    Gao, Bin; Shen, Lei; He, Ke-Wu; Xiao, Wei-Hua

    2015-11-01

    The aim of the present study was to examine the apoptosis of the hepatocellular carcinoma cell line, HepG2, induced by treatment with folic acid-conjugated silica-coated gold nanorods (GNRs@SiO2-FA) in combination with radiotherapy, and to determine the involvement of apoptosis-related proteins. An MTT colorimetric assay was used to assess the biocompatibility of GNRs@SiO2-FA. The distribution of GNRs@SiO2-FA into the cells was observed using transmission electron microscopy (TEM). HepG2 cells cultured in vitro were divided into the following 4 groups: i)the control group (untreated), ii) the GNRs@SiO2-FA group, iii) the radiotherapy group (iodine 125 seeds) and iv) the combination group (treated with GNRs@SiO2-FA and iodine 125 seeds) groups. The apoptosis of the HepG2 cells was detected by flow cytometry. The concentration range of <40 µg/ml GNRs@SiO2-FA was found to be safe for the biological activity of the HepG2 cells. GNRs@SiO2-FA entered the cytoplasm through endocytosis. The apoptotic rates of the HepG2 cells were higher in the GNRs@SiO2-FA and radiotherapy groups than in the control group (P<0.05). The apoptotic rate was also significantly higher in the combination group than the GNRs@SiO2-FA and radiotherapy groups (P<0.05). Taken together, these findings demonstrate that the combination of GNRs@SiO2-FA and radiotherapy more effectively induces the apoptosis of HepG2 cells. These apoptotic effects are achieved by increasing the protein expression of Bax and caspase-3, and inhibiting the protein expression of Bcl-2 and Ki-67. The combination of GNRs@SiO2-FA and radiotherapy may thus prove to be a new approach in the treatment of primary liver cancer.

  20. Glucomannan and glucomannan plus spirulina added to pork significantly block dietary cholesterol effects on lipoproteinemia, arylesterase activity, and CYP7A1 expression in Zucker fa/fa rats.

    PubMed

    González-Torres, Laura; Vázquez-Velasco, Miguel; Olivero-David, Raúl; Bastida, Sara; Benedí, Juana; González, Rafaela Raposo; González-Muñoz, Ma José; Sánchez-Muniz, Francisco J

    2015-12-01

    Zucker fa/fa rats easily develop dyslipidemia and obesity. Restructured pork (RP) is a suitable matrix for including functional ingredients. The effects of glucomannan- RP or glucomannan plus spirulina-enriched RP on plasma lipid/lipoprotein levels, cytochrome P450 7A1 (CYP7A1) expression, and arylesterase activity in growing fa/fa rats fed high-energy, high-fat cholesterol-enriched diets were tested. Groups of six rats each received diet containing 15% control-RP (C), 15% glucomannan-RP diet (G), 15% glucomannan + spirulina-RP diet (GS), and same diets enriched with 2.4% cholesterol and 0.49% cholic acid (cholesterol-enriched control (HC), cholesterol-enriched glucomannan (HG), and cholesterol-enriched glucomannan + spirulina (HGS) diets) over a 7-week period. C diet induced obesity, severe hyperglycemia, moderate hypercholesterolemia, and hypertriglyceridemia. Those facts were not significantly modified by G or GS diets. G diet increased CYP7A1 expression but decreased the total cholesterol/high density lipoproteins (HDL)-cholesterol ratio (p < 0.05) vs. C diet. GS vs. G diet increased (p < 0.05) CYP7A1 expression. HC vs. C diet reduced food intake, body weight gain, and plasma glucose (p < 0.01) but increased cholesterolemia (p < 0.01), lipidemia (plasma cholesterol plus triglycerides) (p < 0.001), cholesterol/triglyceride ratio in very low density lipoproteins (VLDL), and HDL (p < 0.05), cholesterol transported by VLDL and intermediate density lipoproteins (IDL) + low density lipoproteins (LDL), total cholesterol/HDL-cholesterol ratio and CYP7A1 expression (at least p < 0.05). HG and HGS diets vs. HC noticeably reduced lipidemia (p < 0.001), normalized VLDL and IDL + LDL lipid composition, and increased CYP7A1 expression (p < 0.01) but did not modify the cholesterol/HDL-cholesterol ratio. HGS vs. HG decreased triglyceridemia, the triglyceride-glucose (TyG) index and increased arylesterase/HDL-cholesterol activity (p < 0

  1. Potent in vitro synergism of fusidic acid (FA) and berberine chloride (BBR) against clinical isolates of methicillin-resistant Staphylococcus aureus (MRSA).

    PubMed

    Liang, Rong-mei; Yong, Xiao-lan; Duan, Yu-qin; Tan, Yong-hong; Zeng, Ping; Zhou, Zi-ying; Jiang, Yan; Wang, Shi-hua; Jiang, Yun-ping; Huang, Xiao-chun; Dong, Zhao-hui; Hu, Ting-ting; Shi, Hui-qing; Li, Nan

    2014-11-01

    It was found in the present study that combined use of fusidic acid (FA) and berberine chloride (BBR) offered an in vitro synergistic action against 7 of the 30 clinical methicillin-resistant Staphylococcus aureus (MRSA) strains, with a fractional inhibitory concentration (FIC) index ranging from 0.5 to 0.19. This synergistic effect was most pronounced on MRSA 4806, an FA-resistant isolate, with a minimum inhibitory concentration (MIC) value of 1,024 μg/ml. The time-kill curve experiment showed that FA plus BBR yielded a 4.2 log10 c.f.u./ml reduction in the number of MRSA 4806 bacteria after 24-h incubation as compared with BBR alone. Viable count analysis showed that FA plus BBR produced a 3.0 log10 c.f.u./ml decrease in biofilm formation and a 1.5 log10 c.f.u./ml decrease in mature biofilm in viable cell density as compared with BBR alone. In addition, phase contrast micrographs confirmed that biofilm formation was significantly inhibited and mature biofilm was obviously destructed when FA was used in combination with BBR. These results provide evidence that combined use of FA and BBR may prove to be a promising clinical therapeutic strategy against MRSA.

  2. Auxin-Dependent Cell Cycle Reactivation through Transcriptional Regulation of Arabidopsis E2Fa by Lateral Organ Boundary Proteins[W

    PubMed Central

    Berckmans, Barbara; Vassileva, Valya; Schmid, Stephan P.C.; Maes, Sara; Parizot, Boris; Naramoto, Satoshi; Magyar, Zoltan; Kamei, Claire Lessa Alvim; Koncz, Csaba; Bögre, Laszlo; Persiau, Geert; De Jaeger, Geert; Friml, Jiří; Simon, Rüdiger; Beeckman, Tom; De Veylder, Lieven

    2011-01-01

    Multicellular organisms depend on cell production, cell fate specification, and correct patterning to shape their adult body. In plants, auxin plays a prominent role in the timely coordination of these different cellular processes. A well-studied example is lateral root initiation, in which auxin triggers founder cell specification and cell cycle activation of xylem pole–positioned pericycle cells. Here, we report that the E2Fa transcription factor of Arabidopsis thaliana is an essential component that regulates the asymmetric cell division marking lateral root initiation. Moreover, we demonstrate that E2Fa expression is regulated by the LATERAL ORGAN BOUNDARY DOMAIN18/LATERAL ORGAN BOUNDARY DOMAIN33 (LBD18/LBD33) dimer that is, in turn, regulated by the auxin signaling pathway. LBD18/LBD33 mediates lateral root organogenesis through E2Fa transcriptional activation, whereas E2Fa expression under control of the LBD18 promoter eliminates the need for LBD18. Besides lateral root initiation, vascular patterning is disrupted in E2Fa knockout plants, similarly as it is affected in auxin signaling and lbd mutants, indicating that the transcriptional induction of E2Fa through LBDs represents a general mechanism for auxin-dependent cell cycle activation. Our data illustrate how a conserved mechanism driving cell cycle entry has been adapted evolutionarily to connect auxin signaling with control of processes determining plant architecture. PMID:22003076

  3. Suppression of the ELO-2 FA elongation activity results in alterations of the fatty acid composition and multiple physiological defects, including abnormal ultradian rhythms, in Caenorhabditis elegans.

    PubMed Central

    Kniazeva, Marina; Sieber, Matt; McCauley, Scott; Zhang, Kang; Watts, Jennifer L; Han, Min

    2003-01-01

    While the general steps of fatty acid (FA) biosynthesis are well understood, the individual enzymes involved in the elongation of long chain saturated and polyunsaturated FA (PUFA) are largely unknown. Recent research indicates that these enzymes might be of considerable physiological importance for human health. We use Caenorhabditis elegans to study FA elongation activities and associated abnormal phenotypes. In this article we report that the predicted C. elegans F11E6.5/ELO-2 is a functional enzyme with the FA elongation activity. It is responsible for the elongation of palmitic acid and is involved in PUFA biosynthesis. RNAi-mediated suppression of ELO-2 causes an accumulation of palmitate and an associated decrease in the PUFA fraction in triacylglycerides and phospholipid classes. This imbalance in the FA composition results in multiple phenotypic defects such as slow growth, small body size, reproductive defects, and changes in rhythmic behavior. ELO-2 cooperates with the previously reported ELO-1 in 20-carbon PUFA production, and at least one of the enzymes must function to provide normal growth and development in C. elegans. The presented data indicate that suppression of a single enzyme of the FA elongation machinery is enough to affect various organs and systems in worms. This effect resembles syndromic disorders in humans. PMID:12586704

  4. The strawberry (Fragariaxananassa) fruit-specific rhamnogalacturonate lyase 1 (FaRGLyase1) gene encodes an enzyme involved in the degradation of cell-wall middle lamellae.

    PubMed

    Molina-Hidalgo, Francisco J; Franco, Antonio R; Villatoro, Carmen; Medina-Puche, Laura; Mercado, José A; Hidalgo, Miguel A; Monfort, Amparo; Caballero, José Luis; Muñoz-Blanco, Juan; Blanco-Portales, Rosario

    2013-04-01

    Pectins are essential components of primary plant cell walls and middle lamellae, and are related to the consistency of the fruit and its textural changes during ripening. In fact, strawberries become soft as the middle lamellae of cortical parenchyma cells are extensively degraded during ripening, leading to the observed short post-harvest shelf life. Using a custom-made oligonucleotide-based strawberry microarray platform, a putative rhamnogalacturonate lyase gene (FaRGlyase1) was identified. Bioinformatic analysis of the FaRGlyase1 sequence allowed the identification of a conserved rhamnogalacturonate lyase domain, which was also present in other putative RGlyase sequences deposited in the databases. Expression of FaRGlyase1 occurred mainly in the receptacle, concurrently with ripening, and it was positively regulated by abscisic acid and negatively by auxins. FaRGLyase1 gene expression was transiently silenced by injecting live Agrobacterium cells harbouring RNA interference constructs into fruit receptacles. Light and electron microscopy analyses of these transiently silenced fruits revealed that this gene is involved in the degradation of pectins present in the middle lamella region between parenchymatic cells. In addition, genetic linkage association analyses in a strawberry-segregating population showed that FaRGLyase1 is linked to a quantitative trait loci linkage group related to fruit hardness and firmness. The results showed that FaRGlyase1 could play an important role in the fruit ripening-related softening process that reduces strawberry firmness and post-harvest life.

  5. Fasted-state simulated intestinal fluid "FaSSIF-C", a cholesterol containing intestinal model medium for in vitro drug delivery development.

    PubMed

    Khoshakhlagh, Pooneh; Johnson, Raphael; Langguth, Peter; Nawroth, Thomas; Schmueser, Lars; Hellmann, Nadja; Decker, Heinz; Szekely, Noemi Kinga

    2015-07-01

    A set of biorelevant media "fasted-state simulated intestinal fluid with cholesterol (FaSSIF-C)" for the in vitro study of intestinal drug dissolution in the duodenum was developed. These contain cholesterol at the same levels as in human bile: the cholesterol content of FaSSIF-7C is equivalent to healthy female, FaSSIF-10C to healthy male persons, and FaSSIF-13C to several disease cases that lead to gallstones. The fluids were studied in three aspects: biocompatibility, intestinal nanostructure, and solubilizing power of hydrophobic drugs of the BCS class II. The biocompatibility study showed no toxic effects in a Caco-2 cell system. The drug-solubilizing capacity toward Fenofibrate, Danazol, Griseofulvin, and Carbamazepine was assessed as example. It varied with the cholesterol content widely from a fourfold improvement to a twofold reduction. The nanostructure study by dynamic light scattering and small-angle neutron scattering indicated vesicles as the main component of FaSSIF-C in equilibrium (>1 h), but at high cholesterol content, larger particles were observed as a minor contribution. The neutron experiments indicated the presence of complex micelle-vesicle mixtures, even after 1 h development of fed-state bile model to FaSSIF. The results indicate that cholesterol affects some drugs in solubilization and particle size in intestinal model fluids.

  6. Matlab Cluster Ensemble Toolbox

    SciTech Connect

    Sapio, Vincent De; Kegelmeyer, Philip

    2009-04-27

    This is a Matlab toolbox for investigating the application of cluster ensembles to data classification, with the objective of improving the accuracy and/or speed of clustering. The toolbox divides the cluster ensemble problem into four areas, providing functionality for each. These include, (1) synthetic data generation, (2) clustering to generate individual data partitions and similarity matrices, (3) consensus function generation and final clustering to generate ensemble data partitioning, and (4) implementation of accuracy metrics. With regard to data generation, Gaussian data of arbitrary dimension can be generated. The kcenters algorithm can then be used to generate individual data partitions by either, (a) subsampling the data and clustering each subsample, or by (b) randomly initializing the algorithm and generating a clustering for each initialization. In either case an overall similarity matrix can be computed using a consensus function operating on the individual similarity matrices. A final clustering can be performed and performance metrics are provided for evaluation purposes.

  7. Reductive activation in periplasmic nitrate reductase involves chemical modifications of the Mo-cofactor beyond the first coordination sphere of the metal ion.

    PubMed

    Jacques, Julien G J; Fourmond, Vincent; Arnoux, Pascal; Sabaty, Monique; Etienne, Emilien; Grosse, Sandrine; Biaso, Frédéric; Bertrand, Patrick; Pignol, David; Léger, Christophe; Guigliarelli, Bruno; Burlat, Bénédicte

    2014-02-01

    In Rhodobacter sphaeroides periplasmic nitrate reductase NapAB, the major Mo(V) form (the "high g" species) in air-purified samples is inactive and requires reduction to irreversibly convert into a catalytically competent form (Fourmond et al., J. Phys. Chem., 2008). In the present work, we study the kinetics of the activation process by combining EPR spectroscopy and direct electrochemistry. Upon reduction, the Mo (V) "high g" resting EPR signal slowly decays while the other redox centers of the protein are rapidly reduced, which we interpret as a slow and gated (or coupled) intramolecular electron transfer between the [4Fe-4S] center and the Mo cofactor in the inactive enzyme. Besides, we detect spin-spin interactions between the Mo(V) ion and the [4Fe-4S](1+) cluster which are modified upon activation of the enzyme, while the EPR signatures associated to the Mo cofactor remain almost unchanged. This shows that the activation process, which modifies the exchange coupling pathway between the Mo and the [4Fe-4S](1+) centers, occurs further away than in the first coordination sphere of the Mo ion. Relying on structural data and studies on Mo-pyranopterin and models, we propose a molecular mechanism of activation which involves the pyranopterin moiety of the molybdenum cofactor that is proximal to the [4Fe-4S] cluster. The mechanism implies both the cyclization of the pyran ring and the reduction of the oxidized pterin to give the competent tricyclic tetrahydropyranopterin form.

  8. Development and verification of real-time controllers for the F/A-18 vertical fin buffet load alleviation

    NASA Astrophysics Data System (ADS)

    Chen, Yong; Viresh, Wickramasinghe; Zimcik, David

    2006-03-01

    Twin-tail fighter aircraft such as the F/A-18 may experience intense buffet loads at high angles of attack flight conditions and the broadband buffet loads primarily excite the first bending and torsional modes of the vertical fin that results in severe vibration and dynamic stresses on the vertical fin structures. To reduce the premature fatigue failure of the structure and to increase mission availability, a novel hybrid actuation system was developed to actively alleviate the buffet response of a full-scale F/A-18 vertical fin. A hydraulic rudder actuator was used to control the bending mode of the fin by engaging the rudder inertial force. Multiple Macro Fiber Composites actuators were surface mounted to provide induced strain actuation authority to control the torsional mode. Experimental system identification approach was selected to obtain a state-space model of the system using open-loop test data. An LQG controller was developed to minimize the dynamic response of the vertical fin at critical locations. Extensive simulations were conducted to evaluate the control authority of the actuators and the performance of the controller under various buffet load cases and levels. Closed-loop tests were performed on a full-scale F/A-18 empennage and the results validated the effectiveness of the real-time controller as well as the development methodology. In addition, the ground vibration test demonstrated that the hybrid actuation system is a feasible solution to alleviate the vertical tail buffet loads in high performance fighter aircraft.

  9. Interplay between Arabidopsis Activating Factors E2Fb and E2Fa in Cell Cycle Progression and Development1[W

    PubMed Central

    Sozzani, Rosangela; Maggio, Caterina; Varotto, Serena; Canova, Sabrina; Bergounioux, Catherine; Albani, Diego; Cella, Rino

    2006-01-01

    Eukaryotic E2Fs are conserved transcription factors playing crucial and antagonistic roles in several pathways related to cell division, DNA repair, and differentiation. In plants, these processes are strictly intermingled at the growing zone to produce postembryonic development in response to internal signals and environmental cues. Of the six AtE2F proteins found in Arabidopsis (Arabidopsis thaliana), only AtE2Fa and AtE2Fb have been clearly indicated as activators of E2F-responsive genes. AtE2Fa activity was shown to induce S phase and endoreduplication, whereas the function of AtE2Fb and the interrelationship between these two transcription factors was unclear. We have investigated the role played by the AtE2Fb gene during cell cycle and development performing in situ RNA hybridization, immunolocalization of the AtE2Fb protein in planta, and analysis of AtE2Fb promoter activity in transgenic plants. Overexpression of AtE2Fb in transgenic Arabidopsis plants led to striking modifications of the morphology of roots, cotyledons, and leaves that can be ascribed to stimulation of cell division. The accumulation of the AtE2Fb protein in these lines was paralleled by an increased expression of E2F-responsive G1/S and G2/M marker genes. These results suggest that AtE2Fa and AtE2Fb have specific expression patterns and play similar but distinct roles during cell cycle progression. PMID:16514015

  10. In Situ Generation of Active Molybdenum Octahedral Clusters for Photocatalytic Hydrogen Production from Water.

    PubMed

    Feliz, Marta; Puche, Marta; Atienzar, Pedro; Concepción, Patricia; Cordier, Stéphane; Molard, Yann

    2016-08-01

    The photocatalytic hydrogen evolution reaction (HER) from water under homogeneous and heterogeneous conditions is explored for the {Mo6 Br(i) 8 }(4+) cluster core based unit starting from (TBA)2 [Mo6 Br(i) 8 F(a) 6 ] (TBA=tetra-n-butylammonium; "i" and "a" refer to the face-capping inner and terminal apical ligand, respectively). The catalytic activity of {Mo6 Br(i) 8 }(4+) is enhanced by the in situ generation of [Mo6 Br(i) 8 F(a) 5 (OH)(a) ](2-) , [Mo6 Br(i) 8 F(a) 3 (OH)(a) 3 ](2-) , and [Mo6 Br(i) 8 (OH)(a) 6 ](2-) , which are identified by ESIMS, luminescence, and NMR techniques. Full substitution of F(-) by OH(-) leads to the formation of (H3 O)2 [Mo6 Br(i) 8 (OH)(a) 6 ]⋅10 H2 O; its structure was determined by single-crystal XRD. The immobilization of the active {Mo6 Br(i) 8 }(4+) onto graphene oxide (GO) surfaces enhances its stability under catalytic conditions. The catalytic activity of the resulting (TBA)2 Mo6 Br(i) 8 @GO material is improved with respect to GO, but is reduced compared to the activity under homogeneous conditions because of changes in the GO semiconducting properties as well as lower activity and/or accessibility of the anchored cluster. PMID:27314221

  11. ciliaFA: a research tool for automated, high-throughput measurement of ciliary beat frequency using freely available software

    PubMed Central

    2012-01-01

    Background Analysis of ciliary function for assessment of patients suspected of primary ciliary dyskinesia (PCD) and for research studies of respiratory and ependymal cilia requires assessment of both ciliary beat pattern and beat frequency. While direct measurement of beat frequency from high-speed video recordings is the most accurate and reproducible technique it is extremely time consuming. The aim of this study was to develop a freely available automated method of ciliary beat frequency analysis from digital video (AVI) files that runs on open-source software (ImageJ) coupled to Microsoft Excel, and to validate this by comparison to the direct measuring high-speed video recordings of respiratory and ependymal cilia. These models allowed comparison to cilia beating between 3 and 52 Hz. Methods Digital video files of motile ciliated ependymal (frequency range 34 to 52 Hz) and respiratory epithelial cells (frequency 3 to 18 Hz) were captured using a high-speed digital video recorder. To cover the range above between 18 and 37 Hz the frequency of ependymal cilia were slowed by the addition of the pneumococcal toxin pneumolysin. Measurements made directly by timing a given number of individual ciliary beat cycles were compared with those obtained using the automated ciliaFA system. Results The overall mean difference (± SD) between the ciliaFA and direct measurement high-speed digital imaging methods was −0.05 ± 1.25 Hz, the correlation coefficient was shown to be 0.991 and the Bland-Altman limits of agreement were from −1.99 to 1.49 Hz for respiratory and from −2.55 to 3.25 Hz for ependymal cilia. Conclusions A plugin for ImageJ was developed that extracts pixel intensities and performs fast Fourier transformation (FFT) using Microsoft Excel. The ciliaFA software allowed automated, high throughput measurement of respiratory and ependymal ciliary beat frequency (range 3 to 52 Hz) and avoids operator error due to selection bias. We have

  12. New chemical alternative for ozone-depleting substances: HFC-236fa. Final report, December 1996-April 1997

    SciTech Connect

    Smith, N.D.; Brna, T.G.; Gage, C.L.; Hendriks, R.V.

    1997-07-01

    The report gives results of a preliminary evaluation of a new hydrofluoro-carbon (HFC)--HFC-236fa or 1,1,1,3,3,3-hexafluoropropane--asa possible alternative for chlorofluorocarbon (CFC)-114 (1,2-dichloro-1, 1,2,2-tetrafluoroethane) refrigerant for chillers and asa possible fire suppressant replacement for halon-1301 (bromotrifluoromethane). Evaluation tests included an examination of flammability, stability, atmospheric lifetime, thermophysical properties, lubricant miscibility and solubility, materials compatibility, inhalation toxicity, refrigerant performance, heat transfer characteristics, and flame suppression.

  13. Alternatives to CFC-114 in high-temperature heat pumps: Compressor performance with HFC-236ea and HFC-236fa

    SciTech Connect

    Kazachki, G S; Gage, C L; Hendriks, R V

    1996-01-01

    The paper gives results of comprehensive calorimeter tests on a semihermetic compressor with chlorofluorocarbon (CFC)-114, hydrofluorocarbon (HFC)-236ea, and HFC-236fa over a wide range of temperature test conditions: evaporating temperatures from 0 to 35 C and condensing temperatures from 40 to 110 C. Parameters assessed as criteria for performance evaluation and for reliable performance include: cooling capacity; electric power input, current, and voltage; coefficients of performance; compressor volumetric and isentropic efficiencies; and discharge and oil temperatures. Polyolester oil was used as lubricant in the compressor.

  14. Design of an effective bifunctional catalyst organotriphosphonic acid-functionalized ferric alginate (ATMP-FA) and optimization by Box-Behnken model for biodiesel esterification synthesis of oleic acid over ATMP-FA.

    PubMed

    Liu, Wei; Yin, Ping; Liu, Xiguang; Qu, Rongjun

    2014-12-01

    Biodiesel production has become an intense research area because of rapidly depleting energy reserves and increasing petroleum prices together with environmental concerns. This paper focused on the optimization of the catalytic performance in the esterification reaction of oleic acid for biodiesel production over the bifunctional catalyst organotriphosphonic acid-functionalized ferric alginate ATMP-FA. The reaction parameters including catalyst amount, ethanol to oleic acid molar ratio and reaction temperature have been optimized by response surface methodology (RSM) using the Box-Behnken model. It was found that the reaction temperature was the most significant factor, and the best conversion ratio of oleic acid could reach 93.17% under the reaction conditions with 9.53% of catalyst amount and 8.62:1 of ethanol to oleic acid molar ratio at 91.0 °C. The research results show that two catalytic species could work cooperatively to promote the esterification reaction, and the bifunctional ATMP-FA is a potential catalyst for biodiesel production.

  15. Star cluster dynamics.

    PubMed

    Vesperini, Enrico

    2010-02-28

    Dynamical evolution plays a key role in shaping the current properties of star clusters and star cluster systems. A detailed understanding of the effects of evolutionary processes is essential to be able to disentangle the properties that result from dynamical evolution from those imprinted at the time of cluster formation. In this review, I focus my attention on globular clusters, and review the main physical ingredients driving their early and long-term evolution, describe the possible evolutionary routes and show how cluster structure and stellar content are affected by dynamical evolution.

  16. A new clustering strategy

    NASA Astrophysics Data System (ADS)

    Feng, Jian-xin; Tang, Jia-fu; Wang, Guang-xing

    2007-04-01

    On the basis of the analysis of clustering algorithm that had been proposed for MANET, a novel clustering strategy was proposed in this paper. With the trust defined by statistical hypothesis in probability theory and the cluster head selected by node trust and node mobility, this strategy can realize the function of the malicious nodes detection which was neglected by other clustering algorithms and overcome the deficiency of being incapable of implementing the relative mobility metric of corresponding nodes in the MOBIC algorithm caused by the fact that the receiving power of two consecutive HELLO packet cannot be measured. It's an effective solution to cluster MANET securely.

  17. FANCD2 influences replication fork processes and genome stability in response to clustered DSBs

    PubMed Central

    Zhu, Jiayun; Su, Fengtao; Mukherjee, Shibani; Mori, Eiichiro; Hu, Burong; Asaithamby, Aroumougame

    2015-01-01

    Fanconi Anemia (FA) is a cancer predisposition syndrome and the factors defective in FA are involved in DNA replication, DNA damage repair and tumor suppression. Here, we show that FANCD2 is critical for genome stability maintenance in response to high-linear energy transfer (LET) radiation. We found that FANCD2 is monoubiquitinated and recruited to the sites of clustered DNA double-stranded breaks (DSBs) specifically in S/G2 cells after high-LET radiation. Further, FANCD2 facilitated the repair of clustered DSBs in S/G2 cells and proper progression of S-phase. Furthermore, lack of FANCD2 led to a reduced rate of replication fork progression and elevated levels of both replication fork stalling and new origin firing in response to high-LET radiation. Mechanistically, FANCD2 is required for correct recruitment of RPA2 and Rad51 to the sites of clustered DSBs and that is critical for proper processing of clustered DSBs. Significantly, FANCD2-decifient cells exhibited defective chromosome segregation, elevated levels of chromosomal aberrations, and anchorage-independent growth in response to high-LET radiation. These findings establish FANCD2 as a key factor in genome stability maintenance in response to high-LET radiation and as a promising target to improve cancer therapy. PMID:26083937

  18. Unconventional methods for clustering

    NASA Astrophysics Data System (ADS)

    Kotyrba, Martin

    2016-06-01

    Cluster analysis or clustering is a task of grouping a set of objects in such a way that objects in the same group (called a cluster) are more similar (in some sense or another) to each other than to those in other groups (clusters). It is the main task of exploratory data mining and a common technique for statistical data analysis used in many fields, including machine learning, pattern recognition, image analysis, information retrieval, and bioinformatics. The topic of this paper is one of the modern methods of clustering namely SOM (Self Organising Map). The paper describes the theory needed to understand the principle of clustering and descriptions of algorithm used with clustering in our experiments.

  19. Characterisation and differentiation of pigments employed on the façade of ``Noto's Valley'' monuments (Sicily)

    NASA Astrophysics Data System (ADS)

    La Russa, M. F.; Barone, G.; Mazzoleni, P.; Pezzino, A.; Crupi, V.; Majolino, D.

    2008-07-01

    Most of the “Noto’s Valley” monuments façades, located in different towns of Sicily such as Ragusa Ibla, Modica and Noto, present different colours and in many cases the towns themselves are characterized by evident chromatic variations. The knowledge of colour and in particular the characterization of pigments is of utmost importance in the baroque Sicilian buildings, because the peculiarity of the colour is one of the features that makes the “Noto Valley” monuments a World Cultural Heritage site. The present works aim is to characterise and differentiate the pigments used on the façade of monuments and inside the plasters. In particular, we perform a micro-textural and analytical analysis through scanning electron microscopy (SEM) and a mineralogical investigation through the conjunction of optical microscopy and fourier transform infrared spectroscopy (FT-IR). All the experimental results have allowed us to clearly classify the pigments into earths rich in clay minerals and earth containing gypsum. Furthermore, we also show that the earths rich in clay minerals from Ragusa and Modica areas have local provenance.

  20. Transonic Free-To-Roll Analysis of the F/A-18E and F-35 Configurations

    NASA Technical Reports Server (NTRS)

    Owens, D. Bruce; McConnell, Jeffrey K.; Brandon, Jay M.; Hall, Robert M.

    2004-01-01

    The free-to-roll technique is used as a tool for predicting areas of uncommanded lateral motions. Recently, the NASA/Navy/Air Force Abrupt Wing Stall Program extended the use of this technique to the transonic speed regime. Using this technique, this paper evaluates various wing configurations on the pre-production F/A-18E aircraft and the Joint Strike Fighter (F-35) aircraft. The configurations investigated include leading and trailing edge flap deflections, fences, leading edge flap gap seals, and vortex generators. These tests were conducted in the NASA Langley 16-Foot Transonic Tunnel. The analysis used a modification of a figure-of-merit developed during the Abrupt Wing Stall Program to discern configuration effects. The results showed how the figure-of-merit can be used to schedule wing flap deflections to avoid areas of uncommanded lateral motion. The analysis also used both static and dynamic wind tunnel data to provide insight into the uncommanded lateral behavior. The dynamic data was extracted from the time history data using parameter identification techniques. In general, modifications to the pre-production F/A-18E resulted in shifts in angle-of-attack where uncommanded lateral activity occurred. Sealing the gap between the inboard and outboard leading-edge flaps on the Navy version of the F-35 eliminated uncommanded lateral activity or delayed the activity to a higher angle-of-attack.

  1. Genetic modifiers of Lepr{sup fa} associated with variability in insulin production and susceptibility to NIDDM

    SciTech Connect

    Chung, W.K.; Zheng, M.; Chua, M.

    1997-05-01

    In an attempt to identify the genetic basis for susceptibility to non-insulin-dependent diabetes mellitus within the context of obesity, we generated 401 genetically obese Lepr{sup fa}/Lepr{sup fa} F2 WKY13M intercross rats that demonstrated wide variation in multiple phenotypic measures related to diabetes, including plasma glucose concentration, percentage of glycosylated hemoglobin, plasma insulin concentration, and pancreatic islet morphology. Using selective genotyping genome scanning approaches, we have identified three quantitative trait loci (QTLs) on Chr. 1 (LOD 7.1 for pancreatic morpholology), Chr. 12 (LOD 5.1 for body mass index and LOD 3.4 for plasma glucose concentration), and Chr. 16 (P < 0.001 for genotype effect on plasma glucose concentration). The obese F2 progeny demonstrated sexual dimorphism for these traits, with increased diabetes susceptibility in the males appearing at approximately 6 weeks of age, as sexual maturation occurred. For each of the QTLs, the linked phenotypes demonstrated sexual dimorphism (more severe affection in males). The QTL on Chr. 1 maps to a region vicinal to that previously linked to adiposity in studies of diabetes susceptibility in the nonobese Goto-Kakizaki rat, which is genetically closely related to the Wistar counterstrain we employed. Several candidate genes, including tubby (tub), multigenic obesity 1 (Mob1), adult obesity and diabetes (Ad), and insulin-like growth factor-2 (Igf2), map to murine regions homologous to the QTL region identified on rat Chr. 1. 60 refs., 5 figs., 4 tabs.

  2. Multiaxis thrust vectoring using axisymmetric nozzles and postexit vanes on an F/A-18 configuration vehicle

    NASA Technical Reports Server (NTRS)

    Bowers, Albion H.; Noffz, Gregory K.; Grafton, Sue B.; Mason, Mary L.; Peron, Lee R.

    1991-01-01

    A ground-based investigation was conducted on an operational system of multiaxis thrust vectoring using postexit vanes around an axisymmetric nozzle. This thrust vectoring system will be tested on the NASA F/A-18 High Alpha Research Vehicle (HARV) aircraft. The system provides thrust vectoring capability in both pitch and yaw. Ground based data were gathered from two separate tests at NASA Langley Research Center. The first was a static test in the 16-foot Transonic Tunnel Cold-Jet Facility with a 14.25 percent scale model of the axisymmetric nozzle and the postexit vanes. The second test was conducted in the 30 by 60 foot wind tunnel with a 16 percent F/A-18 complete configuration model. Data from the two sets are being used to develop models of jet plume deflection and thrust loss as a function of vane deflection. In addition, an aerodynamic interaction model based on plume deflection angles will be developed. Results from the scale model nozzle test showed that increased vane deflection caused exhaust plume turning. Aerodynamic interaction effects consisted primarily of favorable interaction of moments and unfavorable interaction of forces caused by the vectored jet plume.

  3. Flying Quality Analysis of a JAS 39 Gripen Ministick Controller in an F/A-18 Aircraft

    NASA Technical Reports Server (NTRS)

    Carter, John F.; Stoliker, P. C.

    2000-01-01

    NASA Dryden conducted a handling qualities experiment using a small displacement centerstick controller that Saab-Scania developed for the JAS 39 Gripen aircraft. The centerstick, or ministick, was mounted in the rear cockpit of an F/A-18 aircraft. Production support flight control computers (PSFCC) provided a pilot-selectable research control system. The objectives for this experiment included determining whether the mechanical characteristics of the centerstick controller had any significant effect on the handling qualities of the F/A-18, and determining the usefulness of the PSFCCs for this kind of experiment. Five pilots evaluated closed-loop tracking tasks, including echelon and column formation flight and target following. Cooper-Harper ratings and pilot comments were collected for each maneuver. This paper describes the test system, including the PSFCCs, the Gripen centerstick, and the flight test experiment. The paper presents results of longitudinal handling qualities maneuvers, including low order equivalent systems, Neal-Smith, and controls anticipation parameter analyses. The experiment showed that, while the centerstick controller provided a different aircraft feel, few handling qualities deficiencies resulted. It also demonstrated that the PSFCCs were useful for this kind of investigation.

  4. [Effect of the inoculant strain Sphingomonas paucimobilis 20006FA on the bacterial composition of a phenanthrene-degrading consortium].

    PubMed

    Madueño, L; Coppotelli, B M; Morelli, I S

    2009-01-01

    The effect of the inoculant strain Sphingomonas paucimobilis 20006FA on the bacterial composition of a phenanthrene-degrading consortium obtained from a pristine soil in sequencing batch cultures was studied. Inoculated (F200+1) and non-inoculated (F200) phenanthrene-degrading consortia, were obtained. Bacterial diversity of consortia was studied at cultivable (phenotype and genotype characterization) and non-cultivable (PCR-DGGE) levels. During the successive cultures, a loss in the phenanthrene-degrading capacity and a decrease in the bacterial diversity were observed in both consortia. Although inoculation did not produce any significant changes in the consortia phenanthrene-degrading capacity (29.9% F200 and 27.6% F200+1), it did produce changes in the bacterial composition, showing a differential structural dynamics in the DGGE profiles of the inoculated consortium. In both consortia, a dominant band placed at the same position as that of the DNA of the inoculant strain in the DGGE gel could be observed. However, isolated cultures from the consortia which had an identical band position to that of S. paucimobilis 20006FA in the PCR-DGGE profile showed low similarity with respect to the inoculant strain (RAPD).

  5. The mechanisms underlying overgeneral autobiographical memory: an evaluative review of evidence for the CaR-FA-X model.

    PubMed

    Sumner, Jennifer A

    2012-02-01

    Overgeneral autobiographical memory (OGM) has been found to be an important cognitive phenomenon with respect to depression and trauma-related psychopathology (e.g., posttraumatic stress disorder), and researchers have been interested in better understanding the factors that contribute to this proposed vulnerability factor. The most prominent model of mechanisms underlying OGM to date is Williams et al.'s (2007) CaR-FA-X model. This model proposes that three processes influence OGM: capture and rumination, functional avoidance, and impaired executive control. The author reviews the current state of support for the CaR-FA-X model by evaluating 38 studies that have examined OGM and one or more mechanisms of the model. Collectively, these studies reveal robust support for associations between OGM and both rumination and impaired executive control. OGM also appears to be a cognitive avoidance strategy, and there is evidence that avoiding the retrieval of specific memories reduces distress after an aversive event, at least in the short term. Important issues that have been left unresolved are highlighted, including the nature of the capture phenomenon, the role of trauma in functional avoidance, and the developmental nature of functional avoidance. Recommendations for future research that will enhance understanding of the factors that contribute to OGM are suggested.

  6. What can the Samoan "Fa'afafine" teach us about the Western concept of gender identity disorder in childhood?

    PubMed

    Vasey, Paul L; Bartlett, Nancy H

    2007-01-01

    This article examines whether gender identity disorder in childhood (GIDC) constitutes a mental disorder as outlined by the Diagnostic and Statistical Manual of Mental Disorders, 4th edition (DSM-IV-TR). Data were collected in Samoa, a culture that is characterized by a high degree of social tolerance towards feminine males who are known locally as fa'afafine. The study location was chosen because, unlike Western locales, it afforded the opportunity to examine whether gender-atypical behavior, gender-atypical identity, and sex-atypical identity, in and of themselves, cause distress in sex/gender variant individuals, while simultaneously controlling for the confounding effects of extreme societal intolerance towards such individuals. Because of our focus on the DSM-IV-TR's diagnosis of GIDC, we were specifically interested in ascertaining whether adult fa'afafine recalled a strong and persistent cross-gender identification in childhood, a sense of inappropriateness in the male-typical gender role, a discomfort with their sex, or distress associated with any of the above. In addition, we sought to determine whether parental encouragement or discouragement of cross-gender behaviors influence feelings of distress in relation to the behaviors in question. Based on the cross-cultural information presented here, we conclude that the diagnostic category of GIDC should not occur in its current form in future editions of the DSM, as there is no compelling evidence that cross-gender behaviors or identities, in and of themselves, cause distress in the individual.

  7. Microbial deterioration of artistic tiles from the façade of the Grande Albergo Ausonia & Hungaria (Venice, Italy).

    PubMed

    Giacomucci, Lucia; Bertoncello, Renzo; Salvadori, Ornella; Martini, Ilaria; Favaro, Monica; Villa, Federica; Sorlini, Claudia; Cappitelli, Francesca

    2011-08-01

    The Grande Albergo Ausonia & Hungaria (Venice Lido, Italy) has an Art Nouveau polychrome ceramic coating on its façade, which was restored in 2007. Soon after the conservation treatment, many tiles of the façade decoration showed coloured alterations putatively attributed to the presence of microbial communities. To confirm the presence of the biological deposit and the stratigraphy of the Hungaria tiles, stereomicroscope, optical and environmental scanning electron microscope observations were made. The characterisation of the microbial community was performed using a PCR-DGGE approach. This study reported the first use of a culture-independent approach to identify the total community present in biodeteriorated artistic tiles. The case study examined here reveals that the coloured alterations on the tiles were mainly due to the presence of cryptoendolithic cyanobacteria. In addition, we proved that the microflora present on the tiles was generally greatly influenced by the environment of the Hungaria hotel. We found several microorganisms related to the alkaline environment, which is in the range of the tile pH, and related to the aquatic environment, the presence of the acrylic resin Paraloid B72® used during the 2007 treatment and the pollutants of the Venice lagoon.

  8. The Heliothis virescens cadherin protein expressed in Drosophila S2 cells functions as a receptor for Bacillus thuringiensis Cry1A but not Cry1Fa toxins.

    PubMed

    Jurat-Fuentes, Juan Luis; Adang, Michael J

    2006-08-15

    Genetic knockout of the BtR4 gene encoding the Heliothis virescens cadherin-like protein (HevCaLP) is linked to resistance against Cry1Ac toxin from Bacillus thuringiensis. However, the functional Cry1Ac receptor role of this protein has not been established. We previously proposed HevCaLP as a shared binding site for B. thuringiensis (Bt) Cry1A and Cry1Fa toxins in the midgut epithelium of H. virescens larvae. Considering that Cry1Ac and Cry1Fa are coexpressed in second-generation transgenic cotton for enhanced control of Heliothine and Spodoptera species, our model suggests the possibility of evolution of cross resistance via alteration of HevCaLP. To test whether HevCaLP is a Cry1Ac and Cry1Fa receptor, HevCaLP was transiently expressed on the surface of Drosophila melanogaster Schneider 2 (S2) cells. Expressed HevCaLP bound [(125)I]Cry1A toxins under native (dot blot) and denaturing (ligand blot) conditions. Affinity pull-down assays demonstrated that Cry1Fa does not bind to HevCaLP expressed in S2 cells or in solubilized brush border membrane proteins. Using a fluorescence-based approach, we tested the ability of expressed HevCaLP to mediate toxicity of Cry1A and Cry1Fa toxins. Cry1A toxins killed S2 cells expressing HevCaLP, whereas Cry1Fa toxin did not. Our results demonstrate that HevCaLP is a functional Cry1A but not Cry1Fa receptor. PMID:16893170

  9. Testing the CaR-FA-X Model: Investigating the Mechanisms Underlying Reduced Autobiographical Memory Specificity in Individuals With and Without a History of Depression

    PubMed Central

    Sumner, Jennifer A.; Mineka, Susan; Adam, Emma K.; Craske, Michelle G.; Vrshek-Schallhorn, Suzanne; Wolitzky-Taylor, Kate; Zinbarg, Richard E.

    2014-01-01

    Reduced autobiographical memory specificity (AMS) is an important cognitive phenomenon in major depressive disorder (MDD), but knowledge is lacking about its mechanisms. The CaR-FA-X model of Williams and colleagues proposed that three processes contribute to reduced AMS, alone or in interaction: capture and rumination (CaR), functional avoidance (FA), and impaired executive control (X). However, the entire CaR-FA-X model has not been tested. We addressed this gap in the literature by investigating contributions of the CaR-FA-X mechanisms to reduced AMS, alone or in interaction, in a subset of young adults (N=439) from the Northwestern-UCLA Youth Emotion Project. Participants were classified as those with (n=164) and without (n=275) a history of MDD at AMS assessment. They completed measures of: AMS; rumination (the brooding factor; CaR); childhood, adolescent, and early adulthood adversity (FA); avoidant coping (FA); and verbal fluency (X). Using structural equation modeling, we found greatest support for associations between reduced AMS and the capture and rumination, and impaired executive control mechanisms. In those with and without a history of MDD, brooding and verbal fluency interacted to contribute to reduced AMS. For participants without a history of MDD, lower verbal fluency (indicating impaired executive control) was associated with reduced AMS among those high on brooding. For participants with a history of MDD, lower verbal fluency was associated with reduced AMS among those low on brooding. The first finding was consistent with predictions from the CaR-FA-X model but the latter was not. Implications for conceptualizations of reduced AMS and its mechanisms are discussed. PMID:24978693

  10. Interaction of Boron Clusters with Oxygen: a DFT Study

    NASA Astrophysics Data System (ADS)

    Salavitabar, Kamron; Boggavarapu, Kiran; Kandalam, Anil

    A controlled combustion involving aluminum nanoparticles has often been the focus of studies in the field of solid fuel propellants. However very little focus has been given to the study of boron nanoparticles in controlled combustion. In contrast to aluminum nanoclusters, boron nanoclusters (Bn) are known to exhibit a planar geometries even at the size of n = 19 - 20, and thus offer a greater surface area for interaction with oxygen. Earlier experimental studies have shown that boron nanoclusters exhibit different reactivity with oxygen depending on their size and charge. In this poster, we present our recent density functional theory based results, focusing on the reactivity patterns of neutral and negatively charged B5 cluster with On, where n = 1 - 5; and B6 cluster with On (n = 1 - 2). The effect of charge on the reactivity of boron cluster, variation in the stability of product clusters, i e., neutral and negatively charged B5On (n = 1 - 5) and B6On (n = 1 - 2) are also examined. Financial Support from West Chester University Foundation under FaStR grant is acknowledged.

  11. Information-based clustering

    PubMed Central

    Slonim, Noam; Atwal, Gurinder Singh; Tkačik, Gašper; Bialek, William

    2005-01-01

    In an age of increasingly large data sets, investigators in many different disciplines have turned to clustering as a tool for data analysis and exploration. Existing clustering methods, however, typically depend on several nontrivial assumptions about the structure of data. Here, we reformulate the clustering problem from an information theoretic perspective that avoids many of these assumptions. In particular, our formulation obviates the need for defining a cluster “prototype,” does not require an a priori similarity metric, is invariant to changes in the representation of the data, and naturally captures nonlinear relations. We apply this approach to different domains and find that it consistently produces clusters that are more coherent than those extracted by existing algorithms. Finally, our approach provides a way of clustering based on collective notions of similarity rather than the traditional pairwise measures. PMID:16352721

  12. Convex Discriminative Multitask Clustering.

    PubMed

    Zhang, Xiao-Lei

    2015-01-01

    Multitask clustering tries to improve the clustering performance of multiple tasks simultaneously by taking their relationship into account. Most existing multitask clustering algorithms fall into the type of generative clustering, and none are formulated as convex optimization problems. In this paper, we propose two convex Discriminative Multitask Clustering (DMTC) objectives to address the problems. The first one aims to learn a shared feature representation, which can be seen as a technical combination of the convex multitask feature learning and the convex Multiclass Maximum Margin Clustering (M3C). The second one aims to learn the task relationship, which can be seen as a combination of the convex multitask relationship learning and M3C. The objectives of the two algorithms are solved in a uniform procedure by the efficient cutting-plane algorithm and further unified in the Bayesian framework. Experimental results on a toy problem and two benchmark data sets demonstrate the effectiveness of the proposed algorithms. PMID:26353206

  13. Clusters of galaxies

    NASA Astrophysics Data System (ADS)

    Vikhlinin, A. A.; Kravtsov, A. V.; Markevich, M. L.; Sunyaev, R. A.; Churazov, E. M.

    2014-04-01

    Galaxy clusters are formed via nonlinear growth of primordial density fluctuations and are the most massive gravitationally bound objects in the present Universe. Their number density at different epochs and their properties depend strongly on the properties of dark matter and dark energy, making clusters a powerful tool for observational cosmology. Observations of the hot gas filling the gravitational potential well of a cluster allows studying gasdynamic and plasma effects and the effect of supermassive black holes on the heating and cooling of gas on cluster scales. The work of Yakov Borisovich Zeldovich has had a profound impact on virtually all cosmological and astrophysical studies of galaxy clusters, introducing concepts such as the Harrison-Zeldovich spectrum, the Zeldovich approximation, baryon acoustic peaks, and the Sunyaev-Zeldovich effect. Here, we review the most basic properties of clusters and their role in modern astrophysics and cosmology.

  14. Geophysical data collected from the St. Clair River between Michigan and Ontario, Canada (2008-016-FA)

    USGS Publications Warehouse

    Denny, Jane F.; Foster, D.S.; Worley, C.R.; Irwin, Barry J.

    2011-01-01

    In 2008, the U.S. Geological Survey (USGS), Woods Hole Coastal and Marine Science Center (WHCMSC), in cooperation with the U.S. Army Corps of Engineers conducted a geophysical and sampling survey of the riverbed of the Upper St. Clair River between Port Huron, Mich., and Sarnia, Ontario, Canada. The objectives were to define the Quaternary geologic framework of the riverbed of the St. Clair River to evaluate the relationship between morphologic change of the riverbed and underlying stratigraphy. This report presents the geophysical and sample data collected from the St. Clair River, May 29-June 6, 2008, as part of the International Upper Great Lakes Study, a 5-year project funded by the International Joint Commission of the United States and Canada to examine whether physical changes in the St. Clair River are affecting water levels within upper Great Lakes, to assess regulation plans for outflows from Lake Superior, and to examine the potential effect of climate change on the Great Lakes water levels (http://www.iugls.org). This document makes available the data that were used in a separate report, U.S. Geological Survey Open-File Report 2009-1137, which detailed the interpretations of the Quaternary geologic framework of the region. This report includes a description of the high-resolution acoustic and sediment-sampling systems that were used to map the morphology, surficial sediment distribution, and underlying geology of the Upper St. Clair River during USGS field activity 2008-016-FA (http://quashnet.er.usgs.gov/cgi-bin/datasource/public_ds_info.pl?fa=2008-016-FA). Video and photographs of the riverbed were also collected and are included in this data release. Future analyses will be focused on substrate erosion and its effects on river-channel morphology and geometry. Ultimately, the International Upper Great Lakes Study will attempt to determine where physical changes in the St. Clair River affect water flow and, subsequently, water levels in the Upper Great

  15. Mini-clusters

    NASA Technical Reports Server (NTRS)

    Chinellato, J. A.; Dobrigkeit, C.; Bellandifilho, J.; Lattes, C. M. G.; Menon, M. J.; Navia, C. E.; Pamilaju, A.; Sawayanagi, K.; Shibuya, E. H.; Turtelli, A., Jr.

    1985-01-01

    Experimental results of mini-clusters observed in Chacaltaya emulsion chamber no.19 are summarized. The study was made on 54 single core shower upper and 91 shower clusters of E(gamma) 10 TeV from 30 families which are visible energy greater than 80 TeV and penetrate through both upper and lower detectors of the two-story chamber. The association of hadrons in mini-cluster is made clear from their penetrative nature and microscopic observation of shower continuation in lower chamber. Small P sub t (gamma) of hadrons in mini-clusters remained in puzzle.

  16. Reactions of intermetallic clusters

    NASA Astrophysics Data System (ADS)

    Farley, R. W.; Castleman, A. W., Jr.

    1990-02-01

    Reaction of bismuth-alkali clusters with closed-shell HX acids provides insight into the structures, formation, and stabilities of these intermetallic species. HC1 and HI are observed to quantitatively strip BixNay and BixKy, respectively, of their alkali component, leaving bare bismuth clusters as the only bismuth-containing species detected. Product bismuth clusters exhibit the same distribution observed when pure bismuth is evaporated in the source. Though evaporated simultaneously from the same crucible, this suggests alkali atoms condense onto existing bismuth clusters and have negligible effect on their formation and consequent distribution. The indistinguishibility of reacted and pure bismuth cluster distributions further argues against the simple replacement of alkali atoms with hydrogen in these reactions. This is considered further evidence that the alkali atoms are external to the stable bismuth Zintl anionic structures. Reactivities of BixNay clusters with HC1 are estimated to lie between 3×10-13 for Bi4Na, to greater than 4×10-11 for clusters possessing large numbers of alkali atoms. Bare bismuth clusters are observed in separate experiments to react significantly more slowly with rates of 1-9×10-14 and exhibit little variation of reactivity with size. The bismuth clusters may thus be considered a relatively inert substrate upon which the alkali overlayer reacts.

  17. Management of cluster headache.

    PubMed

    Tfelt-Hansen, Peer C; Jensen, Rigmor H

    2012-07-01

    The prevalence of cluster headache is 0.1% and cluster headache is often not diagnosed or misdiagnosed as migraine or sinusitis. In cluster headache there is often a considerable diagnostic delay - an average of 7 years in a population-based survey. Cluster headache is characterized by very severe or severe orbital or periorbital pain with a duration of 15-180 minutes. The cluster headache attacks are accompanied by characteristic associated unilateral symptoms such as tearing, nasal congestion and/or rhinorrhoea, eyelid oedema, miosis and/or ptosis. In addition, there is a sense of restlessness and agitation. Patients may have up to eight attacks per day. Episodic cluster headache (ECH) occurs in clusters of weeks to months duration, whereas chronic cluster headache (CCH) attacks occur for more than 1 year without remissions. Management of cluster headache is divided into acute attack treatment and prophylactic treatment. In ECH and CCH the attacks can be treated with oxygen (12 L/min) or subcutaneous sumatriptan 6 mg. For both oxygen and sumatriptan there are two randomized, placebo-controlled trials demonstrating efficacy. In both ECH and CCH, verapamil is the prophylactic drug of choice. Verapamil 360 mg/day was found to be superior to placebo in one clinical trial. In clinical practice, daily doses of 480-720 mg are mostly used. Thus, the dose of verapamil used in cluster headache treatment may be double the dose used in cardiology, and with the higher doses the PR interval should be checked with an ECG. At the start of a cluster, transitional preventive treatment such as corticosteroids or greater occipital nerve blockade can be given. In CCH and in long-standing clusters of ECH, lithium, methysergide, topiramate, valproic acid and ergotamine tartrate can be used as add-on prophylactic treatment. In drug-resistant CCH, neuromodulation with either occipital nerve stimulation or deep brain stimulation of the hypothalamus is an alternative treatment strategy

  18. The youngest globular clusters

    NASA Astrophysics Data System (ADS)

    Beck, Sara

    2015-11-01

    It is likely that all stars are born in clusters, but most clusters are not bound and disperse. None of the many protoclusters in our Galaxy are likely to develop into long-lived bound clusters. The super star clusters (SSCs) seen in starburst galaxies are more massive and compact and have better chances of survival. The birth and early development of SSCs takes place deep in molecular clouds, and during this crucial stage the embedded clusters are invisible to optical or UV observations but are studied via the radio-infrared supernebulae (RISN) they excite. We review observations of embedded clusters and identify RISN within 10 Mpc whose exciting clusters have ≈ 106 M⊙ or more in volumes of a few pc3 and which are likely to not only survive as bound clusters, but to evolve into objects as massive and compact as Galactic globulars. These clusters are distinguished by very high star formation efficiency η, at least a factor of 10 higher than the few percent seen in the Galaxy, probably due to the violent disturbances their host galaxies have undergone. We review recent observations of the kinematics of the ionized gas in RISN showing outflows through low-density channels in the ambient molecular cloud; this may protect the cloud from feedback by the embedded H II region.

  19. Clustering versus non-clustering phase synchronizations

    SciTech Connect

    Liu, Shuai; Zhan, Meng

    2014-03-15

    Clustering phase synchronization (CPS) is a common scenario to the global phase synchronization of coupled dynamical systems. In this work, a novel scenario, the non-clustering phase synchronization (NPS), is reported. It is found that coupled systems do not transit to the global synchronization until a certain sufficiently large coupling is attained, and there is no clustering prior to the global synchronization. To reveal the relationship between CPS and NPS, we further analyze the noise effect on coupled phase oscillators and find that the coupled oscillator system can change from CPS to NPS with the increase of noise intensity or system disorder. These findings are expected to shed light on the mechanism of various intriguing self-organized behaviors in coupled systems.

  20. Research on the F/A-18E/F Using a 22%-Dynamically-Scaled Drop Model

    NASA Technical Reports Server (NTRS)

    Croom, M.; Kenney, H.; Murri, D.; Lawson, K.

    2000-01-01

    Research on the F/A-18E/F configuration was conducted using a 22%-dynamically-scaled drop model to study flight dynamics in the subsonic regime. Several topics were investigated including longitudinal response, departure/spin resistance, developed spins and recoveries, and the failing leaf mode. Comparisons to full-scale flight test results were made and show the drop model strongly correlates to the airplane even under very dynamic conditions. The capability to use the drop model to expand on the information gained from full-scale flight testing is also discussed. Finally, a preliminary analysis of an unusual inclined spinning motion, dubbed the "cartwheel", is presented here for the first time.

  1. Release and environmental impact of silver nanoparticles and conventional organic biocides from coated wooden façades.

    PubMed

    Künniger, Tina; Gerecke, Andreas C; Ulrich, Andrea; Huch, Anja; Vonbank, Roger; Heeb, Markus; Wichser, Adrian; Haag, Regula; Kunz, Petra; Faller, Markus

    2014-01-01

    This study represents for the first time a comprehensive assessment of functionality and environmental impacts of metallic silver nanoparticles (Ag-NP) compared to conventional organic biocides. Four different transparent, hydrophobic coatings of wooden outdoor façades were tested during one year outdoor weathering. The total silver release from products with Ag-NP was proportional to the overall erosion of the coating. The results indicate that the Ag-NPs are likely transformed to silver complexes, which are considerably less toxic than ionic silver. The protective effect of the silver containing coatings against mold, blue stain and algae was insufficient, even in immaculate and non-weathered conditions. The release of organic biocides from conventional coatings was dependent on the weather conditions, the type of biocide and the use in the base or top coat. The conventional coating showed a good overall performance free from mold, blue stain and algae until the end of the test period.

  2. FMRFamide-related peptides (FaRPs): A new family of peptides from amphibian defensive skin secretions.

    PubMed

    Wang, Lei; Smyth, Anita; Johnsen, Anders H; Zhou, Mei; Chen, Tianbao; Walker, Brian; Shaw, Chris

    2009-06-01

    Amphibian defensive skin secretions are known to contain a plethora of biologically-active peptides that are often structural and functional analogues of vertebrate neuropeptides. Here we report the structures of two invertebrate neuropeptide analogues, IPPQFMRF amide (IF-8 amide) and EGDEDEFLRF amide (EF-10 amide), from the defensive skin secretions of two different species of African hyperoliid frogs, Kassina maculata and Phylictimantis verrucosus, respectively. These represent the first canonical FMRF amide-related peptides (FaRPs) from a vertebrate source. The cDNA encoding IF-8 amide was cloned from a skin secretion library and found to contain a single copy of the peptide located at the C-terminus of a 58 amino acid residue open-reading frame. These data extend the potential targets of the defensive arsenal of amphibian tegumental secretions to parasitic/predatory invertebrates and the novel peptides described may represent the first vertebrate peptidic endectocides. PMID:19358831

  3. New approach for the identification and validation of a nonlinear F/A-18 model by use of neural networks.

    PubMed

    Boely, Nicolas; Botez, Ruxandra Mihaela

    2010-11-01

    This paper presents a new approach for identifying and validating the F/A-18 aeroservoelastic model, based on flight flutter tests. The neural network (NN), trained with five different flight flutter cases, is validated using 11 other flight flutter test (FFT) data. A total of 16 FFT cases were obtained for all three flight regimes (subsonic, transonic, and supersonic) at Mach numbers ranging between 0.85 and 1.30 and at altitudes of between 5000 and 25 000 ft. The results obtained highlight the efficiency of the multilayer perceptron NN in model identification. Optimization of the NN requires mixing of two proprieties: the hidden layer size reduction and four-layered NN performances. This paper shows that a four-layer NN with only 16 neurons is enough to create an accurate model. The fit coefficients were higher than 92% for both the identification and the validation test data, thus demonstrating accuracy of the NN.

  4. Façade Greening: High-rise apartment building in Milan using pre-stressed concrete slab

    NASA Astrophysics Data System (ADS)

    Sun, Wenning; Li, Mingxin; Han, Yinong; Wang, Moqi; Ansourian, Peter

    2016-08-01

    In this project, one single level of the Façade Greening was designed and modelled using finite element method in Strand7. A static analysis was performed in order to understand the deflection and the stress due to the extra loads imposed by the soil and plants. The results produced by the linear static solver are compared with the strength of the materials and the European limitations. The maximum tension stress which exceeds the tensile strength in concrete is found in the root of the cantilever balcony. An alternative design of the cantilevered balcony with pre-stressed concrete slab is modelled separately for the balcony. Decrease is found in the tension stress and the significant improvement of deflection of the balcony with pre-stressed concrete slab. The dynamic loads such as wind and earthquake did not suggest significant effect on the pre-stressed concrete slab.

  5. Water tunnel flow visualization and wind tunnel data analysis of the F/A-18. [leading edge extension vortex effects

    NASA Technical Reports Server (NTRS)

    Erickson, G. E.

    1982-01-01

    Six degree of freedom studies were utilized to extract a band of yawing and rolling moment coefficients from the F/A-18 aircraft flight records. These were compared with 0.06 scale model data obtained in a 16T wind tunnel facility. The results, indicate the flight test yawing moment data exhibit an improvement over the wind tunnel data to near neutral stability and a significant reduction in lateral stability (again to anear neutral level). These data are consistent with the flight test results since the motion was characterized by a relatively slo departure. Flight tests repeated the slow yaw departure at M 0.3. Only 0.16 scale model wind tunnel data showed levels of lateral stability similar to the flight test results. Accordingly, geometric modifications were investigated on the 0.16 scale model in the 30x60 foot wind tunnel to improve high angle of attack lateral stability.

  6. Capability Description for NASA's F/A-18 TN 853 as a Testbed for the Integrated Resilient Aircraft Control Project

    NASA Technical Reports Server (NTRS)

    Hanson, Curt

    2009-01-01

    The NASA F/A-18 tail number (TN) 853 full-scale Integrated Resilient Aircraft Control (IRAC) testbed has been designed with a full array of capabilities in support of the Aviation Safety Program. Highlights of the system's capabilities include: 1) a quad-redundant research flight control system for safely interfacing controls experiments to the aircraft's control surfaces; 2) a dual-redundant airborne research test system for hosting multi-disciplinary state-of-the-art adaptive control experiments; 3) a robust reversionary configuration for recovery from unusual attitudes and configurations; 4) significant research instrumentation, particularly in the area of static loads; 5) extensive facilities for experiment simulation, data logging, real-time monitoring and post-flight analysis capabilities; and 6) significant growth capability in terms of interfaces and processing power.

  7. Directionality of Electron Transfer in Type I Reaction Center Proteins: High-Frequency EPR Study of PS I with Removed Iron-Sulfur Centers.

    PubMed

    Poluektov, Oleg G; Utschig, Lisa M

    2015-10-29

    A key step of photosynthetic solar energy conversion involves rapid light-induced sequential electron-transfer steps that result in the formation of a stabilized charge-separated state. These primary reactions take place in large integral membrane reaction center (RC) proteins, wherein a series of donor/acceptor cofactors are specifically positioned for efficient electron transfer. RCs can be divided in two classes, Type I and Type II and examples of both types, photosystem I (PS I) and photosystem II (PS II), are involved in the oxygenic photosynthesis of higher plants, cyanobacteria, and algae. High-resolution X-ray crystal structures reveal that PS I and PS II contain two nearly symmetric branches of redox cofactors, termed the A and B branches. While unidirectional ET along the A branch in Type II RCs is well established, there is still a debate of whether primary photochemistry in Type I RCs is unidirectional along the A branch or bidirectional proceeding down both of the A and B branches. Light-induced electron transfer through the B branch has been observed in genetically modified PS I and in native PS I pretreated with strong reducing conditions to reduce three [4Fe-4S] clusters, the terminal electron acceptors of PS I; however, the extent of asymmetry of ET along both cofactor branches remains an open question. To prove that bidirectional ET in PS I is not simply an artifact of a reducing environment or genetic modification and to determine the degree of PS I ET asymmetry, we have examined biochemically modified Synechococcus leopoliensis PS I RCs, wherein the [4Fe-4S] clusters FX, FA, and FB have been removed to prevent secondary ET from phylloquinones (A1A/A1B) to FX. For these Fe-removed proteins, we observe that ET along both the A and B branches occurs with a ratio close to 1. Together with previously reported data, the concomitant structural and kinetic information obtained with HF EPR unambiguously proves the bidirectional nature of ET in PS I over

  8. A nonparametric clustering technique which estimates the number of clusters

    NASA Technical Reports Server (NTRS)

    Ramey, D. B.

    1983-01-01

    In applications of cluster analysis, one usually needs to determine the number of clusters, K, and the assignment of observations to each cluster. A clustering technique based on recursive application of a multivariate test of bimodality which automatically estimates both K and the cluster assignments is presented.

  9. FaQR, required for the biosynthesis of the strawberry flavor compound 4-hydroxy-2,5-dimethyl-3(2H)-furanone, encodes an enone oxidoreductase.

    PubMed

    Raab, Thomas; López-Ráez, Juan Antonio; Klein, Dorothée; Caballero, Jose Luis; Moyano, Enriqueta; Schwab, Wilfried; Muñoz-Blanco, Juan

    2006-04-01

    The flavor of strawberry (Fragaria x ananassa) fruit is dominated by an uncommon group of aroma compounds with a 2,5-dimethyl-3(H)-furanone structure. We report the characterization of an enzyme involved in the biosynthesis of 4-hydroxy-2,5-dimethyl-3(2H)-furanone (HDMF; Furaneol), the key flavor compound in strawberries. Protein extracts were partially purified, and the observed distribution of enzymatic activity correlated with the presence of a single polypeptide of approximately 37 kD. Sequence analysis of two peptide fragments showed total identity with the protein sequence of a strongly ripening-induced, auxin-dependent putative quinone oxidoreductase, Fragaria x ananassa quinone oxidoreductase (FaQR). The open reading frame of the FaQR cDNA consists of 969 bp encoding a 322-amino acid protein with a calculated molecular mass of 34.3 kD. Laser capture microdissection followed by RNA extraction and amplification demonstrated the presence of FaQR mRNA in parenchyma tissue of the strawberry fruit. The FaQR protein was functionally expressed in Escherichia coli, and the monomer catalyzed the formation of HDMF. After chemical synthesis and liquid chromatography-tandem mass spectrometry analysis, 4-hydroxy-5-methyl-2-methylene-3(2H)-furanone was confirmed as a substrate of FaQR and the natural precursor of HDMF. This study demonstrates the function of the FaQR enzyme in the biosynthesis of HDMF as enone oxidoreductase and provides a foundation for the improvement of strawberry flavor and the biotechnological production of HDMF.

  10. Antisense down-regulation of the strawberry β-galactosidase gene FaβGal4 increases cell wall galactose levels and reduces fruit softening

    PubMed Central

    Paniagua, Candelas; Blanco-Portales, Rosario; Barceló-Muñoz, Marta; García-Gago, Juan A.; Waldron, Keith W.; Quesada, Miguel A.; Muñoz-Blanco, Juan; Mercado, José A.

    2016-01-01

    Strawberry softening is characterized by an increase in the solubilization and depolymerization of pectins from cell walls. Galactose release from pectin side chains by β-galactosidase enzymes has been proposed as one reason for the increase in soluble pectins. A putative β-galactosidase gene, FaβGal4, has been identified using a custom-made oligonucleotide-based strawberry microarray platform. FaβGal4 was expressed mainly in the receptacle during fruit ripening, and was positively regulated by abscisic acid and negatively regulated by auxins. To ascertain the role of FaβGal4 in strawberry softening, transgenic plants containing an antisense sequence of this gene under the control of the CaMV35S promoter were generated. Phenotypic analyses were carried out in transgenic plants during three consecutive growing seasons, using non-transformed plants as control. Two out of nine independent transgenic lines yielded fruits that were 30% firmer than control at the ripe stage. FaβGal4 mRNA levels were reduced by 70% in ripe fruits from these selected transgenic lines, but they also showed significant silencing of FaβGal1, although the genes did not share significant similarity. These two transgenic lines also showed an increase in pectin covalently bound to the cell wall, extracted using Na2CO3. The amount of galactose in cell walls from transgenic fruits was 30% higher than in control; notably, the galactose increase was larger in the 1 M KOH fraction, which is enriched in hemicellulose. These results suggest that FaβGal4 participates in the solubilization of covalently bound pectins during ripening, reducing strawberry fruit firmness. PMID:26585222

  11. Antisense down-regulation of the strawberry β-galactosidase gene FaβGal4 increases cell wall galactose levels and reduces fruit softening.

    PubMed

    Paniagua, Candelas; Blanco-Portales, Rosario; Barceló-Muñoz, Marta; García-Gago, Juan A; Waldron, Keith W; Quesada, Miguel A; Muñoz-Blanco, Juan; Mercado, José A

    2016-02-01

    Strawberry softening is characterized by an increase in the solubilization and depolymerization of pectins from cell walls. Galactose release from pectin side chains by β-galactosidase enzymes has been proposed as one reason for the increase in soluble pectins. A putative β-galactosidase gene, FaβGal4, has been identified using a custom-made oligonucleotide-based strawberry microarray platform. FaβGal4 was expressed mainly in the receptacle during fruit ripening, and was positively regulated by abscisic acid and negatively regulated by auxins. To ascertain the role of FaβGal4 in strawberry softening, transgenic plants containing an antisense sequence of this gene under the control of the CaMV35S promoter were generated. Phenotypic analyses were carried out in transgenic plants during three consecutive growing seasons, using non-transformed plants as control. Two out of nine independent transgenic lines yielded fruits that were 30% firmer than control at the ripe stage. FaβGal4 mRNA levels were reduced by 70% in ripe fruits from these selected transgenic lines, but they also showed significant silencing of FaβGal1, although the genes did not share significant similarity. These two transgenic lines also showed an increase in pectin covalently bound to the cell wall, extracted using Na2CO3. The amount of galactose in cell walls from transgenic fruits was 30% higher than in control; notably, the galactose increase was larger in the 1 M KOH fraction, which is enriched in hemicellulose. These results suggest that FaβGal4 participates in the solubilization of covalently bound pectins during ripening, reducing strawberry fruit firmness. PMID:26585222

  12. The mannose-binding lectin gene FaMBL1 is involved in the resistance of unripe strawberry fruits to Colletotrichum acutatum.

    PubMed

    Guidarelli, Michela; Zoli, Lisa; Orlandini, Alessandro; Bertolini, Paolo; Baraldi, Elena

    2014-10-01

    The fungal pathogen Colletotrichum acutatum is the causal agent of strawberry (Fragaria × ananassa) anthracnose. Although the fungus can infect strawberry fruits at both unripe and ripe stages, the symptoms appear only on red ripe fruits. On white unripe fruits, the pathogen becomes quiescent as melanized appressoria after 24 h of interaction. Previous transcriptome analysis has indicated that a mannose-binding lectin (MBL) gene is the most up-regulated gene in 24-h-infected white strawberries, suggesting a role for this gene in the low susceptibility of unripe stages. A time course analysis of the expression of this MBL gene, named FaMBL1 (Fragaria × ananassa MBL 1a), was undertaken to monitor its expression profile in white and red fruits at early interaction times: FaMBL1 was expressed exclusively in white fruit after 24 h, when the pathogen was quiescent. Agrobacterium-mediated transient transformation was used to silence and overexpress the FaMBL1 gene in 24-h-infected white and red strawberries, respectively. FaMBL1-silenced unripe fruits showed an increase in susceptibility to C. acutatum. These 24-h-infected tissues contained subcuticular hyphae, indicating pathogen penetration and active growth. In contrast, overexpression of FaMBL1 in ripe fruits decreased susceptibility; here, 24-h-infected tissues showed a high percentage of ungerminated appressoria, suggesting that the growth of the pathogen had slowed. These data suggest that FaMBL1 plays a crucial role in the resistance of unripe strawberry fruits to C. acutatum. PMID:24690196

  13. Association of protein kinase FA/GSK-3alpha (a proline-directed kinase and a regulator of protooncogenes) with human cervical carcinoma dedifferentiation/progression.

    PubMed

    Yang, S D; Yu, J S; Lee, T T; Ni, M H; Yang, C C; Ho, Y S; Tsen, T Z

    1995-10-01

    Computer analysis of protein phosphorylation-sites sequence revealed that most transcriptional factors and viral oncoproteins are prime targets for regulation of proline-directed protein phosphorylation, suggesting an association of proline-directed protein kinase (PDPK) family with neoplastic transformation and tumorigenesis. In this report, an immunoprecipitate activity assay of protein kinase FA/glycogen synthase kinase-3alpha (kinase FA/GSK-3alpha) (a particular member of PDPK family) has been optimized for human cervical tissue and used to demonstrate for the first time significantly increased (P < 0.001) activity in poorly differentiated cervical carcinoma (82.8 +/- 6.6 U/mg of protein), moderately differentiated carcinoma (36.2 +/- 3.4 U/mg of protein), and well-differentiated carcinoma (18.3 +/- 2.4 U/mg of protein) from 36 human cervical carcinoma samples when compared to 12 normal controls (4.9 +/- 0.6 U/mg of protein). Immunoblotting analysis further revealed that increased activity of kinase FA/GSK-3alpha in cervical carcinoma is due to overexpression of protein synthesis of the kinase. Taken together, the results provide initial evidence that overexpression of protein synthesis and cellular activity of kinase FA/GSK-3alpha may be involved in human cervical carcinoma dedifferentiation/progression, supporting an association of proline-directed protein kinase with neoplastic transformation and tumorigenesis. Since protein kinase FA/GSK-3alpha may function as a possible regulator of transcription factors/proto-oncogenes, the results further suggest that kinase FA/GSK-3alpha may play a potential role in human cervical carcinogenesis, especially in its dedifferentiation and progression.

  14. Evaluating the Possibility of Defining Cut-Off Points for ΔFA% in Order to Differentiate Four Major Types of Peri-Tumoral White Matter Tract Involvement

    PubMed Central

    Deilami, Tourisa; Hadizadeh Kharrazi, Homayoun; Seddighi, Amir Saied; Tanzifi, Parin; Tayebivaljouzi, Reza; Zamani, Fatemeh; Chavoshzadeh Tafti, Atefeh

    2015-01-01

    Background: Diffusion tensor imaging (DTI) and its different scalar values such as fractional anisotropy (FA) have recently been used for evaluation of peri-tumoral white matter (WM) involvement to help define safer surgical excision margins. Objectives: The purpose of this study is to evaluate the possibility of defining diagnostic cut-off points for differentiating four major types of peri-tumoral WM involvement using FA. Patients and Methods: DTI was performed in 12 patients with high presumption of having brain tumors, on a 1.5 T MRI scanner. DTI data was processed by MedINRIA software. Two-hundred region of interests (ROI) were evaluated: 100 in the lesion zone and the rest in the normal WM in the contralateral hemisphere. FA value related to each ROI was measured, and the percentage of FA decrement (ΔFAs%) was calculated. Results: Of the 100 ROIs on the lesion side, 74 were related to high-grade lesions, 23 to low-grade ones, and three to “gliosis”. There were 54 “infiltrated”, 22 “displaced”, 15 “disrupted”, and 9 “edematous” tracts. The major type of fiber involvement, both in low-grade and high-grade tumors was “infiltrated, whereas “edematous” fibers comprised the minority. ΔFA% was more than -35 for “displaced” and “edematous” fibers, and less than -35 for the majority of “disrupted” ones, but “infiltrated” fibers had scattered distribution. Mean ΔFA% was the least for “disrupted”, followed by “infiltrated”, “edematous” and “displaced” parts. Conclusion: Introducing definite diagnostic cut-points was not possible, due to overlap. Based on the fact that “disruption” is the most aggressive process, a sensitivity analysis was carried out for “disrupted” fibers for several presumptive cut-off points. PMID:26528388

  15. Antisense down-regulation of the strawberry β-galactosidase gene FaβGal4 increases cell wall galactose levels and reduces fruit softening.

    PubMed

    Paniagua, Candelas; Blanco-Portales, Rosario; Barceló-Muñoz, Marta; García-Gago, Juan A; Waldron, Keith W; Quesada, Miguel A; Muñoz-Blanco, Juan; Mercado, José A

    2016-02-01

    Strawberry softening is characterized by an increase in the solubilization and depolymerization of pectins from cell walls. Galactose release from pectin side chains by β-galactosidase enzymes has been proposed as one reason for the increase in soluble pectins. A putative β-galactosidase gene, FaβGal4, has been identified using a custom-made oligonucleotide-based strawberry microarray platform. FaβGal4 was expressed mainly in the receptacle during fruit ripening, and was positively regulated by abscisic acid and negatively regulated by auxins. To ascertain the role of FaβGal4 in strawberry softening, transgenic plants containing an antisense sequence of this gene under the control of the CaMV35S promoter were generated. Phenotypic analyses were carried out in transgenic plants during three consecutive growing seasons, using non-transformed plants as control. Two out of nine independent transgenic lines yielded fruits that were 30% firmer than control at the ripe stage. FaβGal4 mRNA levels were reduced by 70% in ripe fruits from these selected transgenic lines, but they also showed significant silencing of FaβGal1, although the genes did not share significant similarity. These two transgenic lines also showed an increase in pectin covalently bound to the cell wall, extracted using Na2CO3. The amount of galactose in cell walls from transgenic fruits was 30% higher than in control; notably, the galactose increase was larger in the 1 M KOH fraction, which is enriched in hemicellulose. These results suggest that FaβGal4 participates in the solubilization of covalently bound pectins during ripening, reducing strawberry fruit firmness.

  16. In-Flight Suppression of a De-Stabilized F/A-18 Structural Mode Using the Space Launch System Adaptive Augmenting Control System

    NASA Technical Reports Server (NTRS)

    Wall, John; VanZwieten, Tannen; Giiligan Eric; Miller, Chris; Hanson, Curtis; Orr, Jeb

    2015-01-01

    Adaptive Augmenting Control (AAC) has been developed for NASA's Space Launch System (SLS) family of launch vehicles and implemented as a baseline part of its flight control system (FCS). To raise the technical readiness level of the SLS AAC algorithm, the Launch Vehicle Adaptive Control (LVAC) flight test program was conducted in which the SLS FCS prototype software was employed to control the pitch axis of Dryden's specially outfitted F/A-18, the Full Scale Advanced Systems Test Bed (FAST). This presentation focuses on a set of special test cases which demonstrate the successful mitigation of the unstable coupling of an F/A-18 airframe structural mode with the SLS FCS.

  17. Investigating potential planetary nebula/cluster pairs

    NASA Astrophysics Data System (ADS)

    Moni Bidin, C.; Majaess, D.; Bonatto, C.; Mauro, F.; Turner, D.; Geisler, D.; Chené, A.-N.; Gormaz-Matamala, A. C.; Borissova, J.; Kurtev, R. G.; Minniti, D.; Carraro, G.; Gieren, W.

    2014-01-01

    Context. Fundamental parameters characterizing the end-state of intermediate-mass stars may be constrained by discovering planetary nebulae (PNe) in open clusters (OCs). Cluster membership may be exploited to establish the distance, luminosity, age, and physical size for PNe, and the intrinsic luminosity and mass of its central star. Aims: Four potential PN-OC associations were investigated to assess the cluster membership for the PNe. Methods: Radial velocities were measured from intermediate-resolution optical spectra, complemented with previous estimates in the literature. When the radial velocity study supported the PN/OC association, we analyzed whether other parameters (e.g., age, distance, reddening, central star brightness) were consistent with this conclusion. Results: Our measurements imply that the PNe VBe 3 and HeFa 1 are not members of the OCs NGC 5999 and NGC 6067, respectively, and that they very likely belong to the background bulge population. Conversely, consistent radial velocities indicate that NGC 2452/NGC 2453 could be associated, but our results are not conclusive so additional observations are warranted. Finally, we demonstrate that all the available information point to He 2-86 being a young, highly internally obscured PN member of NGC 4463. New near-infrared photometry acquired via the Vista Variables in the Via Lactea ESO public survey was used in tandem with existing UBV photometry to measure the distance, reddening, and age of NGC 4463, finding d = 1.55 ± 0.10 kpc, E(B - V) = 0.41 ± 0.02, and τ = 65 ± 10 Myr, respectively. The same values should be adopted for the PN if the proposed cluster membership is confirmed. Based on observations gathered with ESO-VISTA telescope (program ID 172.B-2002).Based on observations gathered at Las Campanas observatory (program ID CN2012A-080).The spectra as FITS files are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc

  18. Mixed-Initiative Clustering

    ERIC Educational Resources Information Center

    Huang, Yifen

    2010-01-01

    Mixed-initiative clustering is a task where a user and a machine work collaboratively to analyze a large set of documents. We hypothesize that a user and a machine can both learn better clustering models through enriched communication and interactive learning from each other. The first contribution or this thesis is providing a framework of…

  19. Cluster Interest Inventory.

    ERIC Educational Resources Information Center

    Herzog, Douglas

    The Cluster Interest Inventory is designed to familiarize students with representative occupations in 13 career clusters: (1) agribusiness and natural resources, (2) business marketing, and office occupations, (3) communications and media, (4) consumer and homemaker, (5) fine arts and humanities, (6) health, (7) manufacturing and processing, (8)…

  20. Matlab Cluster Ensemble Toolbox

    2009-04-27

    This is a Matlab toolbox for investigating the application of cluster ensembles to data classification, with the objective of improving the accuracy and/or speed of clustering. The toolbox divides the cluster ensemble problem into four areas, providing functionality for each. These include, (1) synthetic data generation, (2) clustering to generate individual data partitions and similarity matrices, (3) consensus function generation and final clustering to generate ensemble data partitioning, and (4) implementation of accuracy metrics. Withmore » regard to data generation, Gaussian data of arbitrary dimension can be generated. The kcenters algorithm can then be used to generate individual data partitions by either, (a) subsampling the data and clustering each subsample, or by (b) randomly initializing the algorithm and generating a clustering for each initialization. In either case an overall similarity matrix can be computed using a consensus function operating on the individual similarity matrices. A final clustering can be performed and performance metrics are provided for evaluation purposes.« less

  1. [Cluster headache differential diagnosis].

    PubMed

    Guégan-Massardier, Evelyne; Laubier, Cécile

    2015-11-01

    Cluster headache is characterized by disabling stereotyped headache. Early diagnosis allows appropriate treatment, unfortunately diagnostic errors are frequent. The main differential diagnoses are other primary or essential headaches. Migraine, more frequent and whose diagnosis is carried by excess, trigeminal neuralgia or other trigemino-autonomic cephalgia. Vascular or tumoral underlying condition can mimic cluster headache, neck and brain imaging is recommended, ideally MRI.

  2. Blue emitting undecaplatinum clusters

    NASA Astrophysics Data System (ADS)

    Chakraborty, Indranath; Bhuin, Radha Gobinda; Bhat, Shridevi; Pradeep, T.

    2014-07-01

    A blue luminescent 11-atom platinum cluster showing step-like optical features and the absence of plasmon absorption was synthesized. The cluster was purified using high performance liquid chromatography (HPLC). Electrospray ionization (ESI) and matrix assisted laser desorption ionization (MALDI) mass spectrometry (MS) suggest a composition, Pt11(BBS)8, which was confirmed by a range of other experimental tools. The cluster is highly stable and compatible with many organic solvents.A blue luminescent 11-atom platinum cluster showing step-like optical features and the absence of plasmon absorption was synthesized. The cluster was purified using high performance liquid chromatography (HPLC). Electrospray ionization (ESI) and matrix assisted laser desorption ionization (MALDI) mass spectrometry (MS) suggest a composition, Pt11(BBS)8, which was confirmed by a range of other experimental tools. The cluster is highly stable and compatible with many organic solvents. Electronic supplementary information (ESI) available: Details of experimental procedures, instrumentation, chromatogram of the crude cluster; SEM/EDAX, DLS, PXRD, TEM, FT-IR, and XPS of the isolated Pt11 cluster; UV/Vis, MALDI MS and SEM/EDAX of isolated 2 and 3; and 195Pt NMR of the K2PtCl6 standard. See DOI: 10.1039/c4nr02778g

  3. Muster: Massively Scalable Clustering

    2010-05-20

    Muster is a framework for scalable cluster analysis. It includes implementations of classic K-Medoids partitioning algorithms, as well as infrastructure for making these algorithms run scalably on very large systems. In particular, Muster contains algorithms such as CAPEK (described in reference 1) that are capable of clustering highly distributed data sets in-place on a hundred thousand or more processes.

  4. Illinois' Career Cluster Model

    ERIC Educational Resources Information Center

    Jankowski, Natasha A.; Kirby, Catherine L.; Bragg, Debra D.; Taylor, Jason L.; Oertle, Kathleen M.

    2009-01-01

    This booklet provides information to multiple stakeholders on the implementation of career clusters in Illinois. The booklet is an extension of the previous edition titled "An Introduction to Illinois CTE Programs of Study" (2008), and provides a resource for partners to understand Illinois' Career Cluster Model as its own adaptation of the…

  5. Brightest Cluster Galaxy Identification

    NASA Astrophysics Data System (ADS)

    Leisman, Luke; Haarsma, D. B.; Sebald, D. A.; ACCEPT Team

    2011-01-01

    Brightest cluster galaxies (BCGs) play an important role in several fields of astronomical research. The literature includes many different methods and criteria for identifying the BCG in the cluster, such as choosing the brightest galaxy, the galaxy nearest the X-ray peak, or the galaxy with the most extended profile. Here we examine a sample of 75 clusters from the Archive of Chandra Cluster Entropy Profile Tables (ACCEPT) and the Sloan Digital Sky Survey (SDSS), measuring masked magnitudes and profiles for BCG candidates in each cluster. We first identified galaxies by hand; in 15% of clusters at least one team member selected a different galaxy than the others.We also applied 6 other identification methods to the ACCEPT sample; in 30% of clusters at least one of these methods selected a different galaxy than the other methods. We then developed an algorithm that weighs brightness, profile, and proximity to the X-ray peak and centroid. This algorithm incorporates the advantages of by-hand identification (weighing multiple properties) and automated selection (repeatable and consistent). The BCG population chosen by the algorithm is more uniform in its properties than populations selected by other methods, particularly in the relation between absolute magnitude (a proxy for galaxy mass) and average gas temperature (a proxy for cluster mass). This work supported by a Barry M. Goldwater Scholarship and a Sid Jansma Summer Research Fellowship.

  6. Marketing Occupations. Cluster Guide.

    ERIC Educational Resources Information Center

    Oregon State Dept. of Education, Salem.

    This cluster guide, which is designed to show teachers what specific knowledge and skills qualify high school students for entry-level employment (or postsecondary training) in marketing occupations, is organized into three sections: (1) cluster organization and implementation, (2) instructional emphasis areas, and (3) assessment. The first…

  7. Probability and Cancer Clusters

    ERIC Educational Resources Information Center

    Hamilton-Keene, Rachael; Lenard, Christoper T.; Mills, Terry M.

    2009-01-01

    Recently there have been several news items about possible cancer clusters in the Australian media. The term "cancer cluster" is used when an unusually large number of people in one geographic area, often a workplace, are diagnosed with cancer in a short space of time. In this paper the authors explore this important health issue using probability…

  8. Cosmology with galaxy clusters

    NASA Astrophysics Data System (ADS)

    Sartoris, Barbara

    2015-08-01

    Clusters of galaxies are powerful probes to constrain parameters that describe the cosmological models and to distinguish among different models. Since, the evolution of the cluster mass function and large-scale clustering contain the informations about the linear growth rate of perturbations and the expansion history of the Universe, clusters have played an important role in establishing the current cosmological paradigm. It is crucial to know how to determine the cluster mass from observational quantities when using clusters as cosmological tools. For this, numerical simulations are helpful to define and study robust cluster mass proxies that have minimal and well understood scatter across the mass and redshift ranges of interest. Additionally, the bias in cluster mass determination can be constrained via observations of the strong and weak lensing effect, X-ray emission, the Sunyaev- Zel’dovic effect, and the dynamics of galaxies.A major advantage of X-ray surveys is that the observable-mass relation is tight. Moreover, clusters can be easily identified in X-ray as continuous, extended sources. As of today, interesting cosmological constraints have been obtained from relatively small cluster samples (~102), X-ray selected by the ROSAT satellite over a wide redshift range (0clusters, the ROSAT All-Sky Survey.The next generation of X-ray telescopes will enhance the statistics of detected clusters and enlarge their redshift coverage. In particular, eROSITA will produce a catalog of >105 clusters with photometric redshifts from multi-band optical surveys (e.g. PanSTARRS, DES, and LSST). This will vastly improve upon current cosmological constraints, especially by the synergy with other cluster surveys that

  9. SPASM and Twitch Domains in S-Adenosylmethionine (SAM) Radical Enzymes*

    PubMed Central

    Grell, Tsehai A. J.; Goldman, Peter J.; Drennan, Catherine L.

    2015-01-01

    S-Adenosylmethionine (SAM, also known as AdoMet) radical enzymes use SAM and a [4Fe-4S] cluster to catalyze a diverse array of reactions. They adopt a partial triose-phosphate isomerase (TIM) barrel fold with N- and C-terminal extensions that tailor the structure of the enzyme to its specific function. One extension, termed a SPASM domain, binds two auxiliary [4Fe-4S] clusters and is present within peptide-modifying enzymes. The first structure of a SPASM-containing enzyme, anaerobic sulfatase-maturating enzyme (anSME), revealed unexpected similarities to two non-SPASM proteins, butirosin biosynthetic enzyme 2-deoxy-scyllo-inosamine dehydrogenase (BtrN) and molybdenum cofactor biosynthetic enzyme (MoaA). The latter two enzymes bind one auxiliary cluster and exhibit a partial SPASM motif, coined a Twitch domain. Here we review the structure and function of auxiliary cluster domains within the SAM radical enzyme superfamily. PMID:25477505

  10. Cool Cluster Correctly Correlated

    SciTech Connect

    Varganov, Sergey Aleksandrovich

    2005-01-01

    Atomic clusters are unique objects, which occupy an intermediate position between atoms and condensed matter systems. For a long time it was thought that physical and chemical properties of atomic dusters monotonically change with increasing size of the cluster from a single atom to a condensed matter system. However, recently it has become clear that many properties of atomic clusters can change drastically with the size of the clusters. Because physical and chemical properties of clusters can be adjusted simply by changing the cluster's size, different applications of atomic clusters were proposed. One example is the catalytic activity of clusters of specific sizes in different chemical reactions. Another example is a potential application of atomic clusters in microelectronics, where their band gaps can be adjusted by simply changing cluster sizes. In recent years significant advances in experimental techniques allow one to synthesize and study atomic clusters of specified sizes. However, the interpretation of the results is often difficult. The theoretical methods are frequently used to help in interpretation of complex experimental data. Most of the theoretical approaches have been based on empirical or semiempirical methods. These methods allow one to study large and small dusters using the same approximations. However, since empirical and semiempirical methods rely on simple models with many parameters, it is often difficult to estimate the quantitative and even qualitative accuracy of the results. On the other hand, because of significant advances in quantum chemical methods and computer capabilities, it is now possible to do high quality ab-initio calculations not only on systems of few atoms but on clusters of practical interest as well. In addition to accurate results for specific clusters, such methods can be used for benchmarking of different empirical and semiempirical approaches. The atomic clusters studied in this work contain from a few atoms to

  11. Document clustering methods, document cluster label disambiguation methods, document clustering apparatuses, and articles of manufacture

    DOEpatents

    Sanfilippo, Antonio; Calapristi, Augustin J.; Crow, Vernon L.; Hetzler, Elizabeth G.; Turner, Alan E.

    2009-12-22

    Document clustering methods, document cluster label disambiguation methods, document clustering apparatuses, and articles of manufacture are described. In one aspect, a document clustering method includes providing a document set comprising a plurality of documents, providing a cluster comprising a subset of the documents of the document set, using a plurality of terms of the documents, providing a cluster label indicative of subject matter content of the documents of the cluster, wherein the cluster label comprises a plurality of word senses, and selecting one of the word senses of the cluster label.

  12. Studies in clustering theory

    NASA Astrophysics Data System (ADS)

    Stell, George

    In recent years the properties of percolation models have been studied intensively. The purpose of our project was to develop a general theory of percolation and clustering between particles of arbitrary size and shape, with arbitrary correlations between them. The goal of such a theory includes the treatment of continuum percolation as well as a novel treatment of lattice percolation. We made substantial progress toward this goal. The quantities basic to a description of clustering, the mean cluster size, mean number of clusters, etc., were developed. Concise formulas were given for the terms in such series, and proved, at least for sufficiently low densities, that the series are absolutely convergent. These series can now be used to construct Pade approximants that will allow one to probe the percolation transition. A scaled-particle theory of percolation was developed which gives analytic approximants for the mean number of clusters in a large class of two and three dimensional percolation models. Although this quantity is essential in many applications, e.g., explaining colligative properties, and interpreting low-angle light-scattering data, no systematic studies of it have been done before this work. Recently carried out detailed computer simulations show that the mean number of clusters is given to high accuracy by several of there approximations. Extensions of this work will allow calculation of the complete cluster size distribution.

  13. Extending Beowulf Clusters

    USGS Publications Warehouse

    Steinwand, Daniel R.; Maddox, Brian; Beckmann, Tim; Hamer, George

    2003-01-01

    Beowulf clusters can provide a cost-effective way to compute numerical models and process large amounts of remote sensing image data. Usually a Beowulf cluster is designed to accomplish a specific set of processing goals, and processing is very efficient when the problem remains inside the constraints of the original design. There are cases, however, when one might wish to compute a problem that is beyond the capacity of the local Beowulf system. In these cases, spreading the problem to multiple clusters or to other machines on the network may provide a cost-effective solution.

  14. Partially supervised speaker clustering.

    PubMed

    Tang, Hao; Chu, Stephen Mingyu; Hasegawa-Johnson, Mark; Huang, Thomas S

    2012-05-01

    Content-based multimedia indexing, retrieval, and processing as well as multimedia databases demand the structuring of the media content (image, audio, video, text, etc.), one significant goal being to associate the identity of the content to the individual segments of the signals. In this paper, we specifically address the problem of speaker clustering, the task of assigning every speech utterance in an audio stream to its speaker. We offer a complete treatment to the idea of partially supervised speaker clustering, which refers to the use of our prior knowledge of speakers in general to assist the unsupervised speaker clustering process. By means of an independent training data set, we encode the prior knowledge at the various stages of the speaker clustering pipeline via 1) learning a speaker-discriminative acoustic feature transformation, 2) learning a universal speaker prior model, and 3) learning a discriminative speaker subspace, or equivalently, a speaker-discriminative distance metric. We study the directional scattering property of the Gaussian mixture model (GMM) mean supervector representation of utterances in the high-dimensional space, and advocate exploiting this property by using the cosine distance metric instead of the euclidean distance metric for speaker clustering in the GMM mean supervector space. We propose to perform discriminant analysis based on the cosine distance metric, which leads to a novel distance metric learning algorithm—linear spherical discriminant analysis (LSDA). We show that the proposed LSDA formulation can be systematically solved within the elegant graph embedding general dimensionality reduction framework. Our speaker clustering experiments on the GALE database clearly indicate that 1) our speaker clustering methods based on the GMM mean supervector representation and vector-based distance metrics outperform traditional speaker clustering methods based on the “bag of acoustic features” representation and statistical

  15. H-cluster stars

    NASA Astrophysics Data System (ADS)

    Lai, X. Y.; Gao, C. Y.; Xu, R. X.

    2013-06-01

    The study of dense matter at ultrahigh density has a very long history, which is meaningful for us to understand not only cosmic events in extreme circumstances but also fundamental laws of physics. It is well known that the state of cold matter at supranuclear density depends on the non-perturbative nature of quantum chromodynamics (QCD) and is essential for modelling pulsars. A so-called H-cluster matter is proposed in this paper as the nature of dense matter in reality. In compact stars at only a few nuclear densities but low temperature, quarks could be interacting strongly with each other there. That might render quarks grouped in clusters, although the hypothetical quark clusters in cold dense matter have not been confirmed due to the lack of both theoretical and experimental evidence. Motivated by recent lattice QCD simulations of the H-dibaryons (with structure uuddss), we therefore consider here a possible kind of quark clusters, H-clusters, that could emerge inside compact stars during their initial cooling as the dominant components inside (the degree of freedom could then be H-clusters there). Taking into account the in-medium stiffening effect, we find that at baryon densities of compact stars H-cluster matter could be more stable than nuclear matter. We also find that for the H-cluster matter with lattice structure, the equation of state could be so stiff that it would seem to be `superluminal' in the most dense region. However, the real sound speed for H-cluster matter is in fact difficult to calculate, so at this stage we do not put constraints on our model from the usual requirement of causality. We study the stars composed of H-clusters, i.e. H-cluster stars, and derive the dependence of their maximum mass on the in-medium stiffening effect, showing that the maximum mass could be well above 2 M⊙ as observed and that the resultant mass-radius relation fits the measurement of the rapid burster under reasonable parameters. Besides a general

  16. A critical evaluation of fasted state simulating gastric fluid (FaSSGF) that contains sodium lauryl sulfate and proposal of a modified recipe.

    PubMed

    Aburub, Aktham; Risley, Donald S; Mishra, Dinesh

    2008-01-22

    The aim of this work is to evaluate one of the most commonly used fasted state simulating gastric fluids (FaSSGFs), which contains sodium lauryl sulfate (SLS) (FaSSGF(SLS)), and propose a more appropriate surfactant concentration. Surface tension studies clearly show that the critical micelle concentration (CMC) of SLS in the relevant media (a media whose pH and sodium chloride concentration are representative of physiological conditions) is significantly lower (p<0.05) than 8.67 mM, which is the SLS concentration in FaSSGF(SLS). The CMC of SLS in the relevant media was determined to be 1.75 mM. Based on this a modified recipe is proposed in which the concentration of SLS is sufficient to achieve a surface tension similar to that in vivo without causing artificial micellar solubilization. Solubility, intrinsic dissolution, and GastroPlus modeling studies are presented to support and give rationale for the modified recipe. In addition, a comparison between the modified recipe and other FaSSGFs reported in the literature is made.

  17. 76 FR 73760 - In the Matter of the Designation of Imad Fa'iz Mughniyah also Known as Imad Fayiz Mughniyah as a...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-11-29

    ... published in the Federal Register. Dated: October 24, 2011. Hillary Rodham Clinton, Secretary of State... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF STATE In the Matter of the Designation of Imad Fa'iz Mughniyah also Known as Imad Fayiz Mughniyah as a...

  18. Deficiency of UBE2T, the E2 Ubiquitin Ligase Necessary for FANCD2 and FANCI Ubiquitination, Causes FA-T Subtype of Fanconi Anemia.

    PubMed

    Rickman, Kimberly A; Lach, Francis P; Abhyankar, Avinash; Donovan, Frank X; Sanborn, Erica M; Kennedy, Jennifer A; Sougnez, Carrie; Gabriel, Stacey B; Elemento, Olivier; Chandrasekharappa, Settara C; Schindler, Detlev; Auerbach, Arleen D; Smogorzewska, Agata

    2015-07-01

    Fanconi anemia (FA) is a rare bone marrow failure and cancer predisposition syndrome resulting from pathogenic mutations in genes encoding proteins participating in the repair of DNA interstrand crosslinks (ICLs). Mutations in 17 genes (FANCA-FANCS) have been identified in FA patients, defining 17 complementation groups. Here, we describe an individual presenting with typical FA features who is deficient for the ubiquitin-conjugating enzyme (E2), UBE2T. UBE2T is known to interact with FANCL, the E3 ubiquitin-ligase component of the multiprotein FA core complex, and is necessary for the monoubiquitination of FANCD2 and FANCI. Proband fibroblasts do not display FANCD2 and FANCI monoubiquitination, do not form FANCD2 foci following treatment with mitomycin C, and are hypersensitive to crosslinking agents. These cellular defects are complemented by expression of wild-type UBE2T, demonstrating that deficiency of the protein UBE2T can lead to Fanconi anemia. UBE2T gene gains an alias of FANCT. PMID:26119737

  19. Combining cluster number counts and galaxy clustering

    NASA Astrophysics Data System (ADS)

    Lacasa, Fabien; Rosenfeld, Rogerio

    2016-08-01

    The abundance of clusters and the clustering of galaxies are two of the important cosmological probes for current and future large scale surveys of galaxies, such as the Dark Energy Survey. In order to combine them one has to account for the fact that they are not independent quantities, since they probe the same density field. It is important to develop a good understanding of their correlation in order to extract parameter constraints. We present a detailed modelling of the joint covariance matrix between cluster number counts and the galaxy angular power spectrum. We employ the framework of the halo model complemented by a Halo Occupation Distribution model (HOD). We demonstrate the importance of accounting for non-Gaussianity to produce accurate covariance predictions. Indeed, we show that the non-Gaussian covariance becomes dominant at small scales, low redshifts or high cluster masses. We discuss in particular the case of the super-sample covariance (SSC), including the effects of galaxy shot-noise, halo second order bias and non-local bias. We demonstrate that the SSC obeys mathematical inequalities and positivity. Using the joint covariance matrix and a Fisher matrix methodology, we examine the prospects of combining these two probes to constrain cosmological and HOD parameters. We find that the combination indeed results in noticeably better constraints, with improvements of order 20% on cosmological parameters compared to the best single probe, and even greater improvement on HOD parameters, with reduction of error bars by a factor 1.4-4.8. This happens in particular because the cross-covariance introduces a synergy between the probes on small scales. We conclude that accounting for non-Gaussian effects is required for the joint analysis of these observables in galaxy surveys.

  20. Statistical properties of convex clustering

    PubMed Central

    Tan, Kean Ming; Witten, Daniela

    2016-01-01

    In this manuscript, we study the statistical properties of convex clustering. We establish that convex clustering is closely related to single linkage hierarchical clustering and k-means clustering. In addition, we derive the range of the tuning parameter for convex clustering that yields a non-trivial solution. We also provide an unbiased estimator of the degrees of freedom, and provide a finite sample bound for the prediction error for convex clustering. We compare convex clustering to some traditional clustering methods in simulation studies.

  1. Analysis of F/A-18 Tail Buffet Data Acquired in the 80- by 120-Foot Wind Tunnel

    NASA Technical Reports Server (NTRS)

    James, Kevin D.; Meyn, Larry A.; Schmitz, Fredric H. (Technical Monitor)

    1994-01-01

    Tail buffet studies were conducted on a full-scale, production, F/A-18 fighter aircraft in the 80- by 120-Foot Wind Tunnel of the National Full-Scale Aerodynamic Complex at NASA Ames Research Center at Moffett Field, California. Tail buffet data were acquired over an angle-of-attack range of +20 deg to +40 deg, a side-slip range of -16 deg to + 16 deg, and at wind speeds up to 100 knots. The maximum speed corresponds to a Reynolds number of l2.3 x l0(exp 6) based on mean aerodynamic chord and a Mach number of 0. 15. The port, vertical tail fin was instrumented with ninety-six surface-pressure transducers, arranged in six by eight arrays, on each side of the fin. ne aircraft was also equipped with a removable Leading-Edge Extension (LEX) fence whose purpose is to reduce tail-buffet loads. Current analysis methods for the unsteady aerodynamic pressures and loads are described. Only results for the zero side-slip condition are to be presented, both with and without the LEX fence. Results of the time-averaged, power-spectral analysis are presented for the tail fin bending moments which are derived from the integrated pressure field. Local wave velocities on the tail surfaces are calculated from pressure correlations. It was found that the LEX fence significantly reduces the magnitude of the root-mean-square pressures and bending moments. Scaling and repeatability issues are addressed by comparing the present full scale results for pressures at the 60%-span and 45%-chord location with previous full-scale F/A-18 tail-buffet test in the 80- by 120- Foot Wind Tunnel, and with several small-scale tests. The comparisons show that the tail buffet frequency scales very well with tail chord and free-stream velocity, and that there is good agreement with the previous full-scale test. Root-mean-square pressures and power spectra do not scale as well as the frequency results. Addition of a LEX fence caused tail-buffet loads to be reduced at all model scales.

  2. Prismatic louver active façades for natural illumination and thermal energy gain in high-rise and commercial buildings

    NASA Astrophysics Data System (ADS)

    Vlachokostas, A.; Volkmann, C.; Madamopoulos, N.

    2013-06-01

    High-rise and commercial buildings in urban centers present a great challenge in terms of their energy consumption. Due to maximization of rentable square footage, the preferred urban façade system over the past 50 years has been the "curtain wall", only a few inches thick and comprised of modular steel or aluminum framing and predominant glass infills. The perceived Achilles heel of these modern glass façade systems is their thermal inefficiency: They are inadequate thermal barriers and exhibit excessive solar gain. The excessive solar gain has a negative impact on lighting and cooling loads of the entire building. This negative impact will be further exacerbated with rising energy costs. However, rather than view the glass façade's uncontrolled solar gain merely as a weakness contributing to higher energy consumption, the condition could indeed be considered as related to an energy solution. These glass façades can be retrofitted to operate as a provider of daylight and energy for the rest of the building, taking advantage of the overexposure to the sun. With today's technology, the sun's abundant renewable energy can be the driving force for the energy transition of these building envelopes. Illumination, thermal energy, and electricity production can be directly supplied from the sun, and when correctly and efficiently managed, they can lead to a significantly less energy-intensive building stock. We propose a multi-purpose, prismatic, louver-based façade to perform both daylight and thermal energy harvesting with a goal of offering a better daylight environment for the occupants, and reduce the energy consumption and carbon footprint of the building. While decentralized air-conditioning units are commonly accepted as façade "plug-ins", such decentralization could be utilized with more benefits by passively managing the interior space conditions, without using any extra power. Just as living organisms respond and adapt to the environmental changes in

  3. [Treatment of cluster headache].

    PubMed

    Fabre, N

    2005-07-01

    Remarkable therapeutic improvements have come forward recently for trigemino-autonomic cephalalgias. Attack treatment in cluster headache is based on sumatriptan and oxygen. Non-vasoconstrictive treatments are opening a new post-triptan era but are not yet applicable. Prophylactic treatment of cluster headache is based on verapamil and lithium. The efficacy of anti-epileptic drugs in cluster headache remains to be demonstrated. Surgical treatment aimed at the parasympathetic pathways and at the trigeminal nerve demonstrates a high rate of recurrence and adverse events and questions about the relevance of a "peripheral" target in cluster headache. The efficacy of continuous hypothalamic stimulation in patients with intractable headache constitutes a breakthrough, but must be demonstrated at a larger scale and the benefice/risk ratio must be carefully evaluated. Indomethacin still remains the gold standard in paroxysmal hemicrania treatment. Until recently SUNCT was considered an intractable condition. However there are some reports of complete relief with lamotrigine, topiramate and gabapentin.

  4. Mantis BT Cluster Support

    SciTech Connect

    Riot, V.

    2009-06-05

    The software is a modidication to the Mantis BT V1.5 open source application provided by the mantis BT group to support cluster web servers. It also provides various cosmetic modifications used a LLNL.

  5. Insights into the effects of polygalacturonase FaPG1 gene silencing on pectin matrix disassembly, enhanced tissue integrity, and firmness in ripe strawberry fruits

    PubMed Central

    Posé, Sara; Paniagua, Candelas; Cifuentes, Manuel; Blanco-Portales, Rosario; Quesada, Miguel A.; Mercado, José A.

    2013-01-01

    Antisense-mediated down-regulation of the fruit-specific polygalacturonase (PG) gene FaPG1 in strawberries (Fragaria×ananassa Duch.) has been previously demonstrated to reduce fruit softening and to extend post-harvest shelf life, despite the low PG activity detected in this fruit. The improved fruit traits were suggested to be attributable to a reduced cell wall disassembly due to FaPG1 silencing. This research provides empirical evidence that supports this assumption at the biochemical, cellular, and tissue levels. Cell wall modifications of two independent transgenic antisense lines that demonstrated a >90% reduction in FaPG1 transcript levels were analysed. Sequential extraction of cell wall fractions from control and ripe fruits exhibited a 42% decrease in pectin solubilization in transgenic fruits. A detailed chromatographic analysis of the gel filtration pectin profiles of the different cell wall fractions revealed a diminished depolymerization of the more tightly bound pectins in transgenic fruits, which were solubilized with both a chelating agent and sodium carbonate. The cell wall extracts from antisense FaPG1 fruits also displayed less severe in vitro swelling. A histological analysis revealed more extended cell–cell adhesion areas and an enhanced tissue integrity in transgenic ripe fruits. An immunohistological analysis of fruit sections using the JIM5 antibody against low methyl-esterified pectins demonstrated a higher labelling in transgenic fruit sections, whereas minor differences were observed with JIM7, an antibody that recognizes highly methyl-esterified pectins. These results support that the increased firmness of transgenic antisense FaPG1 strawberry fruits is predominantly due to a decrease in pectin solubilization and depolymerization that correlates with more tightly attached cell wall-bound pectins. This limited disassembly in the transgenic lines indicates that these pectin fractions could play a key role in tissue integrity

  6. Spotlight on Cluster

    NASA Astrophysics Data System (ADS)

    1994-09-01

    For the first and only time during the development and construction of Cluster, all four satellites will be together in the space testing facilities of IABG in Munich. On this unique occasion, ESA invites you, and in particular the visual media, to a joint ESA/Industry briefing on the Cluster project at 10h30 on Tuesday, 11 October at IABG, Einsteinstrasse 20, OTTOBRUNN (Germany). After the meeting, ESA and Industry representatives as well as mission specialists will be available for interviews. A detailed agenda is enclosed. If you intend to participate please return the attached registration form by fax (33.1) 42.73.76.90 to ESA Public Relations Division. CLUSTER BRIEFING Tuesday 11 October 1994 - IABG (Munich) Agenda 09h30 Welcome and first photo opportunity 10h30-10h35 Welcome by IABG Director 10h35-10h40 Introduction by Kurt-Johann Gluitz, Dornier, Vice-President Satellite Systems 10h40-10h55 The ESA science programme by Roger Bonnet, Director of the ESA Science programme 10h55-11h10 The mission overview by Rudi Schmidt, ESA, Cluster Project Scientist 11h10-11h20 The Cluster project by John Credland, ESA Cluster Project Manager 11h20-11h30 Cluster and the European Industry by Gunther Lehn, Dornier Cluster Project Manager 11h30-12h00 Question and answer session 12h00-14h00 Interviews and buffet lunch 13h00-14h00 Second photo opportunity 14h00 End

  7. Wild Duck Cluster

    NASA Technical Reports Server (NTRS)

    2005-01-01

    On April 7, 2005, the Deep Impact spacecraft's Impactor Target Sensor camera recorded this image of M11, the Wild Duck cluster, a galactic open cluster located 6 thousand light years away. The camera is located on the impactor spacecraft, which will image comet Tempel 1 beginning 22 hours before impact until about 2 seconds before impact. Impact with comet Tempel 1 is planned for July 4, 2005.

  8. In Situ Confinement of Ultrasmall Pd Clusters within Nanosized Silicalite-1 Zeolite for Highly Efficient Catalysis of Hydrogen Generation.

    PubMed

    Wang, Ning; Sun, Qiming; Bai, Risheng; Li, Xu; Guo, Guanqi; Yu, Jihong

    2016-06-22

    Well-dispersed and ultrasmall Pd clusters in nanosized silicalite-1 (MFI) zeolite have been prepared under direct hydrothermal conditions using [Pd(NH2CH2CH2NH2)2]Cl2 as precursor. High-resolution scanning transmission electron microscopy studies indicate that the Pd clusters are encapsulated within the intersectional channels of MFI, and the Pd clusters in adjacent channels visually aggregate, forming nanoparticles (NPs) of ∼1.8 nm. The resultant catalysts show an excellent activity and highly efficient H2 generation toward the complete decomposition of formic acid (FA) under mild conditions. Notably, thanks to the further reduced Pd NP size (∼1.5 nm) and the additionally introduced basic sites, the Pd/S-1-in-K catalyst affords turnover frequency values up to 856 h(-1) at 25 °C and 3027 h(-1) at 50 °C. The easy in situ confinement synthesis of metal clusters in zeolites endows the catalysts with superior catalytic activities, excellent recyclability, and high thermal stability, thus opening new perspectives for the practical application of FA as a viable and effective H2 storage material for use in fuel cells. PMID:27248462

  9. Implantation and post-annealing characteristics when impinging small B n clusters into silicon at low fluence

    NASA Astrophysics Data System (ADS)

    Liang, J. H.; Han, H. M.

    2005-01-01

    This study investigated the similarities and differences between B1 monomer and Bn cluster ion implantation into silicon. Small polyatomic boron ions ( Bn- , n = 1-4) with the same atomic boron kinetic energy (20 keV/atom) and atomic fluence (5 × 1013 atoms/cm2) were used. In the simulation, the widely-used SRIM computer code was employed to calculate the as-implanted boron and damage depth profiles of B1 monomer ion implantation in order to make comparisons with experimental results. In the experimental one, the B1 monomer and Bn cluster ions extracted from a tandem accelerator were used to perform ion implantation. Post-annealing methods included one-step (RTA) and two-step (FA + RTA) treatments, where RTA denoted high-temperature rapid thermal annealing at 1050 °C for 10 s and FA represented low-temperature furnace annealing at 550 °C for 1 h. The results revealed that all four as-implanted range parameters (average range, longitudinal range straggling, skewness, kurtosis) increase and tend to saturate as the cluster size increases when compared to those of SRIM-calculated results for the B1 implant. Furthermore, the peculiar damage structures produced by different Bn cluster ions lead to various behaviors in both diffusing and activating boron atoms.

  10. Cluster functional renormalization group

    NASA Astrophysics Data System (ADS)

    Reuther, Johannes; Thomale, Ronny

    2014-01-01

    Functional renormalization group (FRG) has become a diverse and powerful tool to derive effective low-energy scattering vertices of interacting many-body systems. Starting from a free expansion point of the action, the flow of the RG parameter Λ allows us to trace the evolution of the effective one- and two-particle vertices towards low energies by taking into account the vertex corrections between all parquet channels in an unbiased fashion. In this work, we generalize the expansion point at which the diagrammatic resummation procedure is initiated from a free UV limit to a cluster product state. We formulate a cluster FRG scheme where the noninteracting building blocks (i.e., decoupled spin clusters) are treated exactly, and the intercluster couplings are addressed via RG. As a benchmark study, we apply our cluster FRG scheme to the spin-1/2 bilayer Heisenberg model (BHM) on a square lattice where the neighboring sites in the two layers form the individual two-site clusters. Comparing with existing numerical evidence for the BHM, we obtain reasonable findings for the spin susceptibility, the spin-triplet excitation energy, and quasiparticle weight even in coupling regimes close to antiferromagnetic order. The concept of cluster FRG promises applications to a large class of interacting electron systems.

  11. Correlates of avian building strikes at a glass façade museum surrounded by avian habitat

    NASA Astrophysics Data System (ADS)

    Kahle, L.; Flannery, M.; Dumbacher, J. P.

    2013-12-01

    Bird window collisions are the second largest anthropogenic cause of bird deaths in the world. Effective mitigation requires an understanding of which birds are most likely to strike, when, and why. Here, we examine five years of avian window strike data from the California Academy of Sciences - a relatively new museum with significant glass façade situated in Golden Gate Park, San Francisco. We examine correlates of window-killed birds, including age, sex, season, and migratory or sedentary tendencies of the birds. We also examine correlates of window kills such as presence of habitat surrounding the building and overall window area. We found that males are almost three times more likely than females to mortally strike windows, and immature birds are three times more abundant than adults in our window kill dataset. Among seasons, strikes were not notably different in spring, summer, and fall; however they were notably reduced in winter. There was no statistical effect of building orientation (north, south, east, or west), and the presence of avian habitat directly adjacent to windows had a minor effect. We also report ongoing studies examining various efforts to reduce window kill (primarily external decals and large electronic window blinds.) We hope that improving our understanding of the causes of the window strikes will help us strategically reduce window strikes.

  12. Biomineralization History in Low-Temperature Hydrothermal Precipitates in Valu Fa Ridge, Lau Back-arc Basin

    NASA Astrophysics Data System (ADS)

    Zhou, H.; Sun, Z.; Li, J.; Yang, Q.

    2010-12-01

    By means of X-ray diffraction (XRD), scanning electron microscope (SEM), energy dispersive X-ray spectroscopy (EDS), electron probe micro analysis (EPMA), Mössbauer spectroscopy (MS) and molecular biology analysis etc., forming history of low temperature (<150°C) Fe-Si-Mn precipitates from hydrothermal fields in Valu Fa Ridge, Lau Back-arc Basin were studied. It is evidently that the neutrophilic iron oxidizing bacteria such as Leptothrix ochracea, Gallionella ferruginea and the novel PV-1 strain play an important role in formation of Fe-Si-Mn deposits. The Fe oxides were precipitated on the sheath and stalk or as filaments of various species of Fe-oxidizing bacteria in the prime stage when hydrothermal fluid can freely mix with ambient seawater. Then the mineralized filaments combine together to form a three-dimensional network, leading to a promotion of nutrient concentration for the bacteria use. Silica precipitates, except a little of portion adsorbed onto ferrihydrite crusts of the cells under unsaturated state, were mainly precipitated in a later stage when condition for conductive cooling reaches in this network.

  13. Liquid filled prismatic louver façade for enhanced daylighting in high-rise commercial buildings.

    PubMed

    Vlachokostas, A; Madamopoulos, N

    2015-07-27

    A liquid filled prismatic louver (LFPL) façade that can perform daylight and thermal energy harvesting with the potential to offer enhanced natural illumination levels to office spaces and thermally assist secondary thermal driven applications is proposed and analyzed. We focus the present simulation study on the evaluation of daylight enhancement in indoor space by redirecting light from a window opening to the ceiling of the room, and then-after a diffusive reflection from the ceiling-onward to the work plane of the room. Illumination simulations using LightTools, a forward ray tracing illumination simulation software, are performed for an office building space located in New York City. We show that the LFPL system achieves deeper natural light penetration, better uniformity and higher illuminance levels compared to an office space without the LFPL system. We further extend our study to a number of other representative cities in the continental US, covering different climatic zones. The LFPL system achieves good daylight harvesting performance. Finally, we discuss the potential of the LFPL system to capture solar infrared radiation heat within the liquid (e.g., water) volume and use it to assist in secondary thermal energy applications. PMID:26367682

  14. Wickerhamiella siamensis f.a., sp. nov., an endophytic and epiphytic yeast species isolated from sugar cane leaf.

    PubMed

    Khunnamwong, Pannida; Surussawadee, Janjira; Jindamorakot, Sasitorn; Limtong, Savitree

    2014-11-01

    Six strains representing a novel yeast species were isolated from tissue (DMKU-SE106(T), DMKU-SE110, DMKU-SE112 and DMKU-SE132) and the external surface (DMKU-SP335 and DMKU-SP406) of sugar cane leaves collected in Thailand. On the basis of morphological, biochemical, physiological and chemotaxonomic characteristics, and sequence analysis of the D1/D2 region of the LSU rRNA gene and the internal transcribed spacer (ITS) region, the six strains were found to represent a single novel species of the genus Wickerhamiella although the formation of ascospores was not observed. The sequences of the D1/D2 region of the LSU rRNA gene and ITS region of the six strains differed from each other by 0-2 and 2-3 nt substitutions, respectively. The novel species was related most closely to Candida infanticola but with 4.5-4.6% nucleotide substitutions in the D1/D2 region of the LSU rRNA gene and 6.6-7.1% nucleotide substitutions in the ITS region. The name Wickerhamiella siamensis f.a., sp. nov. is proposed. The type strain is DMKU-SE106(T) ( =BCC 61185(T) =NBRC 109697(T) =CBS 13331(T)).

  15. Determination of the stability and control derivatives of the NASA F/A-18 HARV using flight data

    NASA Technical Reports Server (NTRS)

    Napolitano, Marcello R.; Spagnuolo, Joelle M.

    1993-01-01

    This report documents the research conducted for the NASA-Ames Cooperative Agreement No. NCC 2-759 with West Virginia University. A complete set of the stability and control derivatives for varying angles of attack from 10 deg to 60 deg were estimated from flight data of the NASA F/A-18 HARV. The data were analyzed with the use of the pEst software which implements the output-error method of parameter estimation. Discussions of the aircraft equations of motion, parameter estimation process, design of flight test maneuvers, and formulation of the mathematical model are presented. The added effects of the thrust vectoring and single surface excitation systems are also addressed. The results of the longitudinal and lateral directional derivative estimates at varying angles of attack are presented and compared to results from previous analyses. The results indicate a significant improvement due to the independent control surface deflections induced by the single surface excitation system, and at the same time, a need for additional flight data especially at higher angles of attack.

  16. Measurement of enhanced heat transfer coefficient with perforated twisted tape inserts during condensation of R-245fa

    NASA Astrophysics Data System (ADS)

    Khatua, A. K.; Kumar, P.; Singh, H. N.; Kumar, R.

    2016-04-01

    The experimental conductive heat transfer results for flow through inserted perforated twisted tapes in a horizontal tube during condensation of pure R-245fa vapor. The test section consisting of two separate coaxial double pipes assembled in series, acted like a counter flow heat exchanger, where the refrigerant condensed inside the inner tube by rejecting heat to the cooling water flowing inside the outer tube in reversed direction. Data for three perforated twisted tapes having constant twist ratio of 7.1 mm and pitch of perforation as 12.5, 25.0 and 37.5 mm, inserted one by one in full length of test condenser by varying refrigerant mass flux from 100 to 200 kg/m2 s in steps of 50 kg/m2 s for the range of vapor quality from 0.1 to 0.9, were collected together with flow and without insert (plain tube). It has been found that the perforated twisted tape insert having pitch of perforation equal to in order of 12.5 mm gives the highest value of average heat transfer coefficient and is of the order of 37.5 % more than that of the plain one and the correlation predicts the experimental data within an error band of ±15 %.

  17. In-Flight Wing Pressure Distributions for the NASA F/A-18A High Alpha Research Vehicle

    NASA Technical Reports Server (NTRS)

    Davis, Mark C.; Saltzman, John A.

    2000-01-01

    Pressure distributions on the wings of the F/A-18A High Alpha Research Vehicle (HARV) were obtained using both flush-mounted pressure orifices and surface-mounted pressure tubing. During quasi-stabilized 1-g flight, data were gathered at ranges for angle of attack from 5 deg to 70 deg, for angle of sideslip from -12 deg to +12 deg, and for Mach from 0.23 to 0.64, at various engine settings, and with and without the leading edge extension fence installed. Angle of attack strongly influenced the wing pressure distribution, as demonstrated by a distinct flow separation pattern that occurred between the range from 15 deg to 30 deg. Influence by the leading edge extension fence was evident on the inboard wing pressure distribution, but little influence was seen on the outboard portion of the wing. Angle-of-sideslip influence on wing pressure distribution was strongest at low angle of attack. Influence of Mach number was observed in the regions of local supersonic flow, diminishing as angle of attack was increased. Engine throttle setting had little influence on the wing pressure distribution.

  18. Wickerhamiella siamensis f.a., sp. nov., an endophytic and epiphytic yeast species isolated from sugar cane leaf.

    PubMed

    Khunnamwong, Pannida; Surussawadee, Janjira; Jindamorakot, Sasitorn; Limtong, Savitree

    2014-11-01

    Six strains representing a novel yeast species were isolated from tissue (DMKU-SE106(T), DMKU-SE110, DMKU-SE112 and DMKU-SE132) and the external surface (DMKU-SP335 and DMKU-SP406) of sugar cane leaves collected in Thailand. On the basis of morphological, biochemical, physiological and chemotaxonomic characteristics, and sequence analysis of the D1/D2 region of the LSU rRNA gene and the internal transcribed spacer (ITS) region, the six strains were found to represent a single novel species of the genus Wickerhamiella although the formation of ascospores was not observed. The sequences of the D1/D2 region of the LSU rRNA gene and ITS region of the six strains differed from each other by 0-2 and 2-3 nt substitutions, respectively. The novel species was related most closely to Candida infanticola but with 4.5-4.6% nucleotide substitutions in the D1/D2 region of the LSU rRNA gene and 6.6-7.1% nucleotide substitutions in the ITS region. The name Wickerhamiella siamensis f.a., sp. nov. is proposed. The type strain is DMKU-SE106(T) ( =BCC 61185(T) =NBRC 109697(T) =CBS 13331(T)). PMID:25168613

  19. Liquid filled prismatic louver façade for enhanced daylighting in high-rise commercial buildings.

    PubMed

    Vlachokostas, A; Madamopoulos, N

    2015-07-27

    A liquid filled prismatic louver (LFPL) façade that can perform daylight and thermal energy harvesting with the potential to offer enhanced natural illumination levels to office spaces and thermally assist secondary thermal driven applications is proposed and analyzed. We focus the present simulation study on the evaluation of daylight enhancement in indoor space by redirecting light from a window opening to the ceiling of the room, and then-after a diffusive reflection from the ceiling-onward to the work plane of the room. Illumination simulations using LightTools, a forward ray tracing illumination simulation software, are performed for an office building space located in New York City. We show that the LFPL system achieves deeper natural light penetration, better uniformity and higher illuminance levels compared to an office space without the LFPL system. We further extend our study to a number of other representative cities in the continental US, covering different climatic zones. The LFPL system achieves good daylight harvesting performance. Finally, we discuss the potential of the LFPL system to capture solar infrared radiation heat within the liquid (e.g., water) volume and use it to assist in secondary thermal energy applications.

  20. Smoke generators show the twisting paths of wingtip vortices behind two NASA Dryden F/A-18's used in

    NASA Technical Reports Server (NTRS)

    2001-01-01

    Smoke generators show the twisting paths of wingtip vortices behind two NASA Dryden F/A-18's used in the Autonomous Formation Flight (AFF) program during flight #743. The lead aircraft, F-18 #845 (NASA Dryden's Systems Research Aircraft), piloted by Craig Bomben, is followed closely by another F-18, #847, piloted by Dick Ewers. A vortex is a spiraling current of air emanating from aircraft wingtips as they fly. By mapping the vortex pattern and using sophisticated software to put the trailing aircraft in the optimum location, the energy of the vortex could result in fuel savings for the follower aircraft of 15 percent or more. Autonomous Formation Flight (AFF) is intended to allow an aircraft to fly in close formation over long distances using advanced positioning and controls technology. It utilizes Global Positioning System satellites and inertial navigation systems to position two or more aircraft in formation, with an accuracy of a few inches. This capability is expected to yield fuel efficiency improvements.

  1. Flow Visualization Techniques in Wind Tunnel Tests of a Full-Scale F/A-18 Aircraft

    NASA Technical Reports Server (NTRS)

    Lanser, Wendy R.; Botha, Gavin J.; James, Kevin D.; Bennett, Mark; Crowder, James P.; Cooper, Don; Olson, Lawrence (Technical Monitor)

    1994-01-01

    The proposed paper presents flow visualization performed during experiments conducted on a full-scale F/A-18 aircraft in the 80- by 120-Foot Wind-Tunnel at NASA Ames Research Center. The purpose of the flow-visualization experiments was to document the forebody and leading edge extension (LEX) vortex interaction along with the wing flow patterns at high angles of attack and low speed high Reynolds number conditions. This investigation used surface pressures in addition to both surface and off-surface flow visualization techniques to examine the flow field on the forebody, canopy, LEXS, and wings. The various techniques used to visualize the flow field were fluorescent tufts, flow cones treated with reflective material, smoke in combination with a laser light sheet, and a video imaging system for three-dimension vortex tracking. The flow visualization experiments were conducted over an angle of attack range from 20 deg to 45 deg and over a sideslip range from -10 deg to 10 deg. The various visualization techniques as well as the pressure distributions were used to understand the flow field structure. The results show regions of attached and separated flow on the forebody, canopy, and wings as well as the vortical flow over the leading-edge extensions. This paper will also present flow visualization comparisons with the F-18 HARV flight vehicle and small-scale oil flows on the F-18.

  2. An Overview of Controls and Flying Qualities Technology on the F/A-18 High Alpha Research Vehicle

    NASA Technical Reports Server (NTRS)

    Pahle, Joseph W.; Wichman, Keith D.; Foster, John V.; Bundick, W. Thomas

    1996-01-01

    The NASA F/A-18 High Alpha Research Vehicle (HARV) has been the flight test bed of a focused technology effort to significantly increase maneuvering capability at high angles of attack. Development and flight test of control law design methodologies, handling qualities metrics, performance guidelines, and flight evaluation maneuvers are described. The HARV has been modified to include two research control effectors, thrust vectoring, and actuated forebody strakes in order to provide increased control power at high angles of attack. A research flight control system has been used to provide a flexible, easily modified capability for high-angle-of-attack research controls. Different control law design techniques have been implemented and flight-tested, including eigenstructure assignment, variable gain output feedback, pseudo controls, and model-following. Extensive piloted simulation has been used to develop nonlinear performance guide-lines and handling qualities criteria for high angles of attack. This paper reviews the development and evaluation of technologies useful for high-angle-of-attack control. Design, development, and flight test of the research flight control system, control laws, flying qualities specifications, and flight test maneuvers are described. Flight test results are used to illustrate some of the lessons learned during flight test and handling qualities evaluations.

  3. An Inlet Distortion Assessment During Aircraft Departures at High Angle of Attack for an F/A-18A Aircraft

    NASA Technical Reports Server (NTRS)

    Steenken, William G.; Williams, John G.; Yuhas, Andrew J.; Walsh, Kevin R.

    1997-01-01

    The F404-GE-400-powered F/A-18A High Alpha Research Vehicle (HARV) was used to examine the quality of inlet airflow during departed flight maneuvers, that is, during flight outside the normal maneuvering envelope where control surfaces have little or no effectiveness. Six nose-left and six nose-right departures were initiated at Mach numbers between 0.3 and 0.4 at an altitude of 35 kft. The entry yaw rates were approximately 40 to 90 deg/sec. Engine surges were encountered during three of the nose-left and one of the nose-right departures. Time-variant inlet-total-pressure distortion levels at the engine face did not significantly exceed those at maximum angle-of-attack and sideslip maneuvers during controlled flight. Surges caused by inlet distortion levels resulted from a combination of high levels of inlet distortion and rapid changes in aircraft position. These rapid changes indicate a combination of engine support and gyroscopic loads being applied to the engine structure that impact the aerodynamic stability of the compressor through changes in the rotor-to-case clearances. This document presents the slides from an oral presentation.

  4. High-Alpha Handling Qualities Flight Research on the NASA F/A-18 High Alpha Research Vehicle

    NASA Technical Reports Server (NTRS)

    Wichman, Keith D.; Pahle, Joseph W.; Bahm, Catherine; Davidson, John B.; Bacon, Barton J.; Murphy, Patrick C.; Ostroff, Aaron J.; Hoffler, Keith D.

    1996-01-01

    A flight research study of high-angle-of-attack handling qualities has been conducted at the NASA Dryden Flight Research Center using the F/A-18 High Alpha Research Vehicle (HARV). The objectives were to create a high-angle-of-attack handling qualities flight database, develop appropriate research evaluation maneuvers, and evaluate high-angle-of-attack handling qualities guidelines and criteria. Using linear and nonlinear simulations and flight research data, the predictions from each criterion were compared with the pilot ratings and comments. Proposed high-angle-of-attack nonlinear design guidelines and proposed handling qualities criteria and guidelines developed using piloted simulation were considered. Recently formulated time-domain Neal-Smith guidelines were also considered for application to high-angle-of-attack maneuvering. Conventional envelope criteria were evaluated for possible extension to the high-angle-of-attack regime. Additionally, the maneuvers were studied as potential evaluation techniques, including a limited validation of the proposed standard evaluation maneuver set. This paper gives an overview of these research objectives through examples and summarizes result highlights. The maneuver development is described briefly, the criteria evaluation is emphasized with example results given, and a brief discussion of the database form and content is presented.

  5. A xylanase from Streptomyces sp. FA1: heterologous expression, characterization, and its application in Chinese steamed bread.

    PubMed

    Xu, Yang; Wu, Jing; Zheng, Kaixuan; Wu, Dan

    2016-05-01

    Xylanases (EC 3.2.1.8) are hydrolytic enzymes that have found widespread application in the food, feed, and paper-pulp industries. Streptomyces sp. FA1 xynA was expressed as a secreted protein in Pichia pastoris, and the xylanase was applied to the production of Chinese steamed bread for the first time. The optimal pH and the optimal temperature of XynA were 5.5 and 60 °C, respectively. Using beechwood as substrate, the K m and V max were 2.408 mg mL(-1) and 299.3 µmol min(-1) mg(-1), respectively. Under optimal conditions, a 3.6-L bioreactor produced 1374 U mL(-1) of XynA activity at a protein concentration of 6.3 g L(-1) after 132 h of fermentation. Use of recombinant XynA led to a greater increase in the specific volume of the CSB than could be achieved using commercial xylanase under optimal conditions. This study provides the basis for the application of the enzyme in the baking industry. PMID:26803505

  6. Fully automated measurement of field-dependent AMS using MFK1-FA Kappabridge equipped with 3D rotator

    NASA Astrophysics Data System (ADS)

    Chadima, Martin; Studynka, Jan

    2013-04-01

    Low-field magnetic susceptibility of paramagnetic and diamagnetic minerals is field-independent by definition being also field-independent in pure magnetite. On the other hand, in pyrrhotite, hematite and high-Ti titanomagnetite it may be clearly field-dependent. Consequently, the field-dependent AMS enables the magnetic fabric of the latter group of minerals to be separated from the whole-rock AMS. The methods for the determination of the field-dependent AMS consist of separate measurements of each specimen in several fields within the Rayleigh Law range and subsequent processing in which the field-independent and field-dependent AMS components are calculated. The disadvantage of this technique is that each specimen must be measured several times, which is relatively laborious and time consuming. Recently, a new 3D rotator was developed for the MFK1-FA Kappabridge, which rotates the specimen simultaneously about two axes with different velocities. The measurement is fully automated in such a way that, once the specimen is inserted into the rotator, it requires no additional manipulation to measure the full AMS tensor. Consequently, the 3D rotator enables to measure the AMS tensors in the pre-set field intensities without any operator interference. Whole procedure is controlled by newly developed Safyr5 software; once the measurements are finished, the acquired data are immediately processed and can be visualized in a standard way.

  7. Effects of the inoculant strain Sphingomonas paucimobilis 20006FA on soil bacterial community and biodegradation in phenanthrene-contaminated soil.

    PubMed

    Coppotelli, B M; Ibarrolaza, A; Del Panno, M T; Morelli, I S

    2008-02-01

    The effects of the inoculant strain Sphingomonas paucimobilis 20006FA (isolated from a phenanthrene-contaminated soil) on the dynamics and structure of microbial communities and phenanthrene elimination rate were studied in soil microcosms artificially contaminated with phenanthrene. The inoculant managed to be established from the first inoculation as it was evidenced by denaturing gradient gel electrophoresis analysis, increasing the number of cultivable heterotrophic and PAH-degrading cells and enhancing phenanthrene degradation. These effects were observed only during the inoculation period. Nevertheless, the soil biological activity (dehydrogenase activity and CO(2) production) showed a late increase. Whereas gradual and successive changes in bacterial community structures were caused by phenanthrene contamination, the inoculation provoked immediate, significant, and stable changes on soil bacterial community. In spite of the long-term establishment of the inoculated strain, at the end of the experiment, the bioaugmentation did not produce significant changes in the residual soil phenanthrene concentration and did not improve the residual effects on the microbial soil community.

  8. Behavioral Clustering of School Children.

    ERIC Educational Resources Information Center

    Huberty, Carl J.; And Others

    This article illustrates how a cluster analysis can be conducted, validated, and interpreted. Data normed for a behavioral assessment instrument with 14 scales on a nationally representative sample of U.S. school children were utilized. The discussion explores the similarity index, cluster method, cluster typology, cluster validity, cluster…

  9. ROTATING GLOBULAR CLUSTERS

    SciTech Connect

    Bianchini, P.; Varri, A. L.; Bertin, G.; Zocchi, A.

    2013-07-20

    Internal rotation is thought to play a major role in the dynamics of some globular clusters. However, in only a few cases has internal rotation been studied by the quantitative application of realistic and physically justified global models. Here, we present a dynamical analysis of the photometry and three-dimensional kinematics of {omega} Cen, 47 Tuc, and M15, by means of a recently introduced family of self-consistent axisymmetric rotating models. The three clusters, characterized by different relaxation conditions, show evidence of differential rotation and deviations from sphericity. The combination of line-of-sight velocities and proper motions allows us to determine their internal dynamics, predict their morphology, and estimate their dynamical distance. The well-relaxed cluster 47 Tuc is interpreted very well by our model; internal rotation is found to explain the observed morphology. For M15, we provide a global model in good agreement with the data, including the central behavior of the rotation profile and the shape of the ellipticity profile. For the partially relaxed cluster {omega} Cen, the selected model reproduces the complex three-dimensional kinematics; in particular, the observed anisotropy profile, characterized by a transition from isotropy to weakly radial anisotropy and then to tangential anisotropy in the outer parts. The discrepancy found for the steep central gradient in the observed line-of-sight velocity dispersion profile and for the ellipticity profile is ascribed to the condition of only partial relaxation of this cluster and the interplay between rotation and radial anisotropy.

  10. Clustering in bubbly liquids

    NASA Astrophysics Data System (ADS)

    Figueroa, Bernardo; Zenit, Roberto

    2004-11-01

    We are conducting experiments to determine the amount of clustering that occurs when small gas bubbles ascend in clean water. In particular, we are interested in flows for which the liquid motion around the bubbles can be described, with a certain degree of accuracy, using potential flow theory. This model is applicable for the case of bubbly liquids in which the Reynolds number is large and the Weber number is small. To clearly observe the formation of bubble clusters we propose the use of a Hele-Shaw-type channel. In this thin channel the bubbles cannot overlap in the depth direction, therefore the identification of bubble clusters cannot be misinterpreted. Direct video image analysis is performed to calculate the velocity and size of the bubbles, as well as the formation of clusters. Although the walls do affect the motion of the bubbles, the clustering phenomena does occur and has the same qualitative behavior as in fully three-dimensional flows. A series of preliminary measurements are presented. A brief discussion of our plans to perform PIV measurements to obtain the liquid velocity fields is also presented.

  11. Supervised clustering of genes

    PubMed Central

    Dettling, Marcel; Bühlmann, Peter

    2002-01-01

    Background We focus on microarray data where experiments monitor gene expression in different tissues and where each experiment is equipped with an additional response variable such as a cancer type. Although the number of measured genes is in the thousands, it is assumed that only a few marker components of gene subsets determine the type of a tissue. Here we present a new method for finding such groups of genes by directly incorporating the response variables into the grouping process, yielding a supervised clustering algorithm for genes. Results An empirical study on eight publicly available microarray datasets shows that our algorithm identifies gene clusters with excellent predictive potential, often superior to classification with state-of-the-art methods based on single genes. Permutation tests and bootstrapping provide evidence that the output is reasonably stable and more than a noise artifact. Conclusions In contrast to other methods such as hierarchical clustering, our algorithm identifies several gene clusters whose expression levels clearly distinguish the different tissue types. The identification of such gene clusters is potentially useful for medical diagnostics and may at the same time reveal insights into functional genomics. PMID:12537558

  12. Friedreich's Ataxia (FA)

    MedlinePlus

    ... About Friedreich’s Ataxia Updated December 2009 Michelle Moffitt Smith Michelle and James Smith at their wedding Dear Friends: W hen I ... for a doctorate. I met my husband, James Smith, through MDA’s magazine, Quest. He also has a ...

  13. Multiferroic rhodium clusters.

    PubMed

    Ma, Lei; Moro, Ramiro; Bowlan, John; de Heer, Walt A; Kirilyuk, Andrei

    2014-10-10

    Simultaneous magnetic and electric deflection measurements of rhodium clusters (Rh(N), 6 ≤ N ≤ 40) reveal ferromagnetism and ferroelectricity at low temperatures, while neither property exists in the bulk metal. Temperature-independent magnetic moments (up to 1 μ(B) per atom) are observed, and superparamagnetic blocking temperatures up to 20 K. Ferroelectric dipole moments on the order of 1D with transition temperatures up to 30 K are observed. Ferromagnetism and ferroelectricity coexist in rhodium clusters in the measured size range, with size-dependent variations in the transition temperatures that tend to be anticorrelated in the range n = 6-25. Both effects diminish with size and essentially vanish at N = 40. The ferroelectric properties suggest a Jahn-Teller ground state. These experiments represent the first example of multiferroic behavior in pure metal clusters. PMID:25375737

  14. Installed F/A-18 inlet flow calculations at 30 degrees angle-of-attack: A comparative study

    NASA Technical Reports Server (NTRS)

    Smith, C. Frederic; Podleski, Steve D.

    1994-01-01

    NASA Lewis is currently engaged in a research effort as a team member of the High Alpha Technology Program (HATP) within NASA. This program utilizes a specially equipped F/A-18, the High Alpha Research Vehicle (HARV), in an ambitious effort to improve the maneuverability of high-performance military aircraft at low subsonic speed, high angle of attack conditions. The overall objective of the Lewis effort is to develop inlet technology that will ensure efficient airflow delivery to the engine during these maneuvers. One part of the Lewis approach utilizes computational fluid dynamics codes to predict the installed performance of inlets for these highly maneuverable aircraft. Full Navier-Stokes (FNS) calculations on the installed F/A-18 inlet at 30 degrees angle of attack, 0 degrees yaw, and a freestream Mach number of 0.2 have been obtained in this study using an algebraic turbulence model with two grids (original and revised). Results obtained with the original grid were used to determine where further grid refinements and additional geometry were needed. In order to account properly for the external effects, the forebody, leading edge extension (LEX), ramp, and wing were included with inlet geometry. In the original grid, the diverter, LEX slot, and leading edge flap were not included due to insufficient geometry definition, but were included in a revised grid. In addition, a thin-layer Navier-Stokes (TLNS) code is used with the revised grid and the numerical results are compared to those obtained with the FNS code. The TLNS code was used to evaluate the effects on the solution using a code with more recent CFD developments such as upwinding with TVD schemes versus central differencing with artificial dissipation. The calculations are compared to a limited amount of available experimental data. The predicted forebody/fuselage surface static pressures compared well with data of all solutions. The predicted trajectory of the vortex generated under the LEX was

  15. Wind tunnel investigations of forebody strakes for yaw control on F/A-18 model at subsonic and transonic speeds

    NASA Technical Reports Server (NTRS)

    Erickson, Gary E.; Murri, Daniel G.

    1993-01-01

    Wind tunnel investigations have been conducted of forebody strakes for yaw control on 0.06-scale models of the F/A-18 aircraft at free-stream Mach numbers of 0.20 to 0.90. The testing was conducted in the 7- by 10-Foot Transonic Tunnel at the David Taylor Research Center and the Langley 7- by 10-Foot High-Speed Tunnel. The principal objectives of the testing were to determine the effects of the Mach number and the strake plan form on the strake yaw control effectiveness and the corresponding strake vortex induced flow field. The wind tunnel model configurations simulated an actuated conformal strake deployed for maximum yaw control at high angles of attack. The test data included six-component forces and moments on the complete model, surface static pressure distributions on the forebody and wing leading-edge extensions, and on-surface and off-surface flow visualizations. The results from these studies show that the strake produces large yaw control increments at high angles of attack that exceed the effect of conventional rudders at low angles of attack. The strake yaw control increments diminish with increasing Mach number but continue to exceed the effect of rudder deflection at angles of attack greater than 30 degrees. The character of the strake vortex induced flow field is similar at subsonic and transonic speeds. Cropping the strake planform to account for geometric and structural constraints on the F-18 aircraft has a small effect on the yaw control increments at subsonic speeds and no effect at transonic speeds.

  16. Wind tunnel investigation of vortex flows on F/A-18 configuration at subsonic through transonic speed

    NASA Technical Reports Server (NTRS)

    Erickson, Gary E.

    1991-01-01

    A wind tunnel experiment was conducted in the David Taylor Research Center 7- by 10-Foot Transonic Tunnel of the wing leading-edge extension (LEX) and forebody vortex flows at subsonic and transonic speeds about a 0.06-scale model of the F/A-18. The primary goal was to improve the understanding and control of the vortical flows, including the phenomena of vortex breakdown and vortex interactions with the vertical tails. Laser vapor screen flow visualizations, LEX, and forebody surface static pressures, and six-component forces and moments were obtained at angles of attack of 10 to 50 degrees, free-stream Mach numbers of 0.20 to 0.90, and Reynolds numbers based on the wing mean aerodynamic chord of 0.96 x 10(exp 6) to 1.75 x 10(exp 6). The wind tunnel results were correlated with in-flight flow visualizations and handling qualities trends obtained by NASA using an F-18 High-Alpha Research Vehicle (HARV) and by the Navy and McDonnell Douglas on F-18 aircraft with LEX fences added to improve the vertical tail buffet environment. Key issues that were addressed include the sensitivity of the vortical flows to the Reynolds number and Mach number; the reduced vertical tail excitation, and the corresponding flow mechanism, in the presence of the LEX fence; the repeatability of data obtained during high angle-of-attack wind tunnel testing of F-18 models; the effects of particle seeding for flow visualization on the quantitative model measurements; and the interpretation of off-body flow visualizations obtained using different illumination and particle seeding techniques.

  17. In-Flight Suppression of an Unstable F/A-18 Structural Mode Using the Space Launch System Adaptive Augmenting Control System

    NASA Technical Reports Server (NTRS)

    VanZwieten, Tannen S.; Gilligan, Eric T.; Wall, John H.; Miller, Christopher J.; Hanson, Curtis E.; Orr, Jeb S.

    2015-01-01

    NASA's Space Launch System (SLS) Flight Control System (FCS) includes an Adaptive Augmenting Control (AAC) component which employs a multiplicative gain update law to enhance the performance and robustness of the baseline control system for extreme off-nominal scenarios. The SLS FCS algorithm including AAC has been flight tested utilizing a specially outfitted F/A-18 fighter jet in which the pitch axis control of the aircraft was performed by a Non-linear Dynamic Inversion (NDI) controller, SLS reference models, and the SLS flight software prototype. This paper describes test cases from the research flight campaign in which the fundamental F/A-18 airframe structural mode was identified using post-flight frequency-domain reconstruction, amplified to result in closed loop instability, and suppressed in-flight by the SLS adaptive control system.

  18. In-Flight Suppression of a Destabilized F/A-18 Structural Mode Using the Space Launch System Adaptive Augmenting Control System

    NASA Technical Reports Server (NTRS)

    Wall, John H.; VanZwieten, Tannen S.; Gilligan, Eric T.; Miller, Christopher J.; Hanson, Curtis E.; Orr, Jeb S.

    2015-01-01

    NASA's Space Launch System (SLS) Flight Control System (FCS) includes an Adaptive Augmenting Control (AAC) component which employs a multiplicative gain update law to enhance the performance and robustness of the baseline control system for extreme off nominal scenarios. The SLS FCS algorithm including AAC has been flight tested utilizing a specially outfitted F/A-18 fighter jet in which the pitch axis control of the aircraft was performed by a Non-linear Dynamic Inversion (NDI) controller, SLS reference models, and the SLS flight software prototype. This paper describes test cases from the research flight campaign in which the fundamental F/A-18 airframe structural mode was identified using frequency-domain reconstruction of flight data, amplified to result in closed loop instability, and suppressed in-flight by the SLS adaptive control system.

  19. Radical SAM catalysis via an organometallic intermediate with an Fe-[5'-C]-deoxyadenosyl bond.

    PubMed

    Horitani, Masaki; Shisler, Krista; Broderick, William E; Hutcheson, Rachel U; Duschene, Kaitlin S; Marts, Amy R; Hoffman, Brian M; Broderick, Joan B

    2016-05-13

    Radical S-adenosylmethionine (SAM) enzymes use a [4Fe-4S] cluster to cleave SAM to initiate diverse radical reactions. These reactions are thought to involve the 5'-deoxyadenosyl radical intermediate, which has not yet been detected. We used rapid freeze-quenching to trap a catalytically competent intermediate in the reaction catalyzed by the radical SAM enzyme pyruvate formate-lyase activating enzyme. Characterization of the intermediate by electron paramagnetic resonance and (13)C, (57)Fe electron nuclear double-resonance spectroscopies reveals that it contains an organometallic center in which the 5' carbon of a SAM-derived deoxyadenosyl moiety forms a bond with the unique iron site of the [4Fe-4S] cluster. Discovery of this intermediate extends the list of enzymatic bioorganometallic centers to the radical SAM enzymes, the largest enzyme superfamily known, and reveals intriguing parallels to B12 radical enzymes.

  20. Bacillus thuringiensis DB27 produces two novel protoxins, Cry21Fa1 and Cry21Ha1, which act synergistically against nematodes.

    PubMed

    Iatsenko, Igor; Boichenko, Iuliia; Sommer, Ralf J

    2014-05-01

    Bacillus thuringiensis has been widely used as a biopesticide, primarily for the control of insect pests, but some B. thuringiensis strains specifically target nematodes. However, nematicidal virulence factors of B. thuringiensis are poorly investigated. Here, we describe virulence factors of nematicidal B. thuringiensis DB27 using Caenorhabditis elegans as a model. We show that B. thuringiensis DB27 kills a number of free-living and animal-parasitic nematodes via intestinal damage. Its virulence factors are plasmid-encoded Cry protoxins, since plasmid-cured derivatives do not produce Cry proteins and are not toxic to nematodes. Whole-genome sequencing of B. thuringiensis DB27 revealed multiple potential nematicidal factors, including several Cry-like proteins encoded by different plasmids. Two of these proteins appear to be novel and show high similarity to Cry21Ba1. Named Cry21Fa1 and Cry21Ha1, they were expressed in Escherichia coli and fed to C. elegans, resulting in intoxication, intestinal damage, and death of nematodes. Interestingly, the effects of the two protoxins on C. elegans are synergistic (synergism factor, 1.8 to 2.5). Using purified proteins, we determined the 50% lethal concentrations (LC50s) for Cry21Fa1 and Cry21Ha1 to be 13.6 μg/ml and 23.9 μg/ml, respectively, which are comparable to the LC50 of nematicidal Cry5B. Finally, we found that signaling pathways which protect C. elegans against Cry5B toxin are also required for protection against Cry21Fa1. Thus, B. thuringiensis DB27 produces novel nematicidal protoxins Cry21Fa1 and Cry21Ha1 with synergistic action, which highlights the importance of naturally isolated strains as a source of novel toxins.

  1. Alcohol metabolism in human cells causes DNA damage and activates the Fanconi anemia – breast cancer susceptibility (FA-BRCA) DNA damage response network

    PubMed Central

    Abraham, Jessy; Balbo, Silvia; Crabb, David; Brooks, P.J.

    2011-01-01

    Background We recently reported that exposure of human cells in vitro to acetaldehyde resulted in activation of the Fanconi anemia-breast cancer associated (FA-BRCA) DNA damage response network. Methods To determine whether intracellular generation of acetaldehyde from ethanol metabolism can cause DNA damage and activate the FA-BRCA network, we engineered HeLa cells to metabolize alcohol by expression of human alcohol dehydrogenase 1B. Results Incubation of HeLa-ADH1B cells with ethanol (20 mM) resulted in acetaldehyde accumulation in the media which was prevented by co-incubation with 4-methyl pyrazole (4-MP), a specific inhibitor of ADH. Ethanol treatment of HeLa-ADH1B cells produced a 4-fold increase in the acetaldehyde-DNA adduct, N2-ethylidene-dGuo, and also resulted in activation of the Fanconi anemia -breast cancer susceptibility (FA-BRCA) DNA damage response network, as indicated by a monoubiquitination of FANCD2, and phosphorylation of BRCA1. Ser 1524 was identified as one site of BRCA1 phosphorylation. The increased levels of DNA adducts, FANCD2 monoubiquitination, and BRCA1 phosphorylation were all blocked by 4-MP, indicating that acetaldehyde, rather than ethanol itself, was responsible for all three responses. Importantly, the ethanol concentration we used is within the range that can be attained in the human body during social drinking. Conclusions Our results indicate that intracellular metabolism of ethanol to acetaldehyde results in DNA damage which activates the FA-BRCA DNA damage response network. PMID:21919919

  2. Characterization of the photolyase-like iron sulfur protein PhrB from Agrobacterium tumefaciens by Mössbauer spectroscopy

    NASA Astrophysics Data System (ADS)

    Bauer, T. O.; Graf, D.; Lamparter, T.; Schünemann, V.

    2014-04-01

    High field Mössbauer spectroscopy has been used to characterize the [4Fe-4S] 2 +cluster of the protein PhrB from Agrobacterium tumefaciens which belongs to the cryptochrome/photolyase family (CPF) and which biological function has previously been shown to be DNA repair. Mössbauer spectra taken of the as prepared protein reveal δ = 0. 42 mms - 1, and Δ E Q = 1. 26 mms - 1as well as an asymmetry parameter of η = 0. 8. These parameters are characteristic for a ferredoxin-type [4Fe-4S] 2 +cluster. In order to investigate whether this cluster is involved in DNA-repair the protein has also been studied in its photoactivated state during DNA binding. The so obtained data sets exhibit essentially the same Mössbauer parameters as those of the non-activated PhrB. This indicates that during DNA repair the [4Fe-4S] 2 +cluster of PhrB has no significant amounts of transition states which have conformational changes compared to the resting state of the protein and which have life times of several seconds or longer.

  3. Metabolic engineering of E. coli top 10 for production of vanillin through FA catabolic pathway and bioprocess optimization using RSM.

    PubMed

    Chakraborty, Debkumar; Gupta, Gaganjot; Kaur, Baljinder

    2016-12-01

    Metabolic engineering and construction of recombinant Escherichia coli strains carrying feruloyl-CoA synthetase and enoyl-CoA hydratase genes for the bioconversion of ferulic acid to vanillin offers an alternative way to produce vanillin. Isolation and designing of fcs and ech genes was carried out using computer assisted protocol and the designed vanillin biosynthetic gene cassette was cloned in pCCIBAC expression vector for introduction in E. coli top 10. Recombinant strain was implemented for the statistical optimization of process parameters influencing F A to vanillin biotransformation. CCD matrix constituted of process variables like FA concentration, time, temperature and biomass with intracellular, extracellular and total vanillin productions as responses. Production was scaled up and 68 mg/L of vanillin was recovered from 10 mg/L of FA using cell extracts from 1 mg biomass within 30 min. Kinetic activity of enzymes were characterized. From LCMS-ESI analysis a metabolic pathway of FA degradation and vanillin production was predicted. PMID:27591788

  4. Simulation model of the F/A-18 high angle-of-attack research vehicle utilized for the design of advanced control laws

    NASA Technical Reports Server (NTRS)

    Strickland, Mark E.; Bundick, W. Thomas; Messina, Michael D.; Hoffler, Keith D.; Carzoo, Susan W.; Yeager, Jessie C.; Beissner, Fred L., Jr.

    1996-01-01

    The 'f18harv' six degree-of-freedom nonlinear batch simulation used to support research in advanced control laws and flight dynamics issues as part of NASA's High Alpha Technology Program is described in this report. This simulation models an F/A-18 airplane modified to incorporate a multi-axis thrust-vectoring system for augmented pitch and yaw control power and actuated forebody strakes for enhanced aerodynamic yaw control power. The modified configuration is known as the High Alpha Research Vehicle (HARV). The 'f18harv' simulation was an outgrowth of the 'f18bas' simulation which modeled the basic F/A-18 with a preliminary version of a thrust-vectoring system designed for the HARV. The preliminary version consisted of two thrust-vectoring vanes per engine nozzle compared with the three vanes per engine actually employed on the F/A-18 HARV. The modeled flight envelope is extensive in that the aerodynamic database covers an angle-of-attack range of -10 degrees to +90 degrees, sideslip range of -20 degrees to +20 degrees, a Mach Number range between 0.0 and 2.0, and an altitude range between 0 and 60,000 feet.

  5. Metabolic engineering of E. coli top 10 for production of vanillin through FA catabolic pathway and bioprocess optimization using RSM.

    PubMed

    Chakraborty, Debkumar; Gupta, Gaganjot; Kaur, Baljinder

    2016-12-01

    Metabolic engineering and construction of recombinant Escherichia coli strains carrying feruloyl-CoA synthetase and enoyl-CoA hydratase genes for the bioconversion of ferulic acid to vanillin offers an alternative way to produce vanillin. Isolation and designing of fcs and ech genes was carried out using computer assisted protocol and the designed vanillin biosynthetic gene cassette was cloned in pCCIBAC expression vector for introduction in E. coli top 10. Recombinant strain was implemented for the statistical optimization of process parameters influencing F A to vanillin biotransformation. CCD matrix constituted of process variables like FA concentration, time, temperature and biomass with intracellular, extracellular and total vanillin productions as responses. Production was scaled up and 68 mg/L of vanillin was recovered from 10 mg/L of FA using cell extracts from 1 mg biomass within 30 min. Kinetic activity of enzymes were characterized. From LCMS-ESI analysis a metabolic pathway of FA degradation and vanillin production was predicted.

  6. Health Occupations Cluster.

    ERIC Educational Resources Information Center

    Walraven, Catherine; And Others

    These instructional materials consist of a series of curriculum worksheets that cover tasks to be mastered by students in health occupations cluster programs. Covered in the curriculum worksheets are diagnostic procedures; observing/recording/reporting/planning; safety; nutrition/elimination; hygiene/personal care/comfort;…

  7. Nuclear Cluster Physics

    SciTech Connect

    Kamimura, Masayasu

    2011-05-06

    Predictive power of theory needs good models and accurate calculation methods to solve the Schroedinger equations of the systems concerned. We present some examples of successful predictions based on the nuclear cluster models of light nuclei and hypernuclei and on the calculation methods that have been developed by Kyushu group.

  8. Clustering in Bubble Suspensions

    NASA Astrophysics Data System (ADS)

    Zenit, Roberto

    2000-11-01

    A monidisperse bubble suspension is studied experimentally for the limit in which the Weber number is small and the Reynolds number is large. For this regime the suspension can be modeled using potential flow theory to describe the dynamics of the interstitial fluid. Complete theoretical descriptions have been composed (Spelt and Sangani, 1998) to model the behavior of these suspensions. Bubble clustering is a natural instability that arises from the potential flow considerations, in which bubbles tend to align in horizontal rafts as they move upwards. The appearance of bubble clusters was recently corroborated experimentally by Zenit et al. (2000), who found that although clusters did appear, their strength was not as strong as the predictions. Experiments involving gravity driven shear flows are used to explain the nature of the clustering observed in these type of flows. Balances of the bubble phase pressure (in terms of a calculated diffusion coefficient) and the Maxwell pressure (from the potential flow description) are presented to predict the stability of the bubble suspension. The predictions are compared with experimental results.

  9. Infrared Coronet Cluster

    NASA Technical Reports Server (NTRS)

    2007-01-01

    While perhaps not quite as well known as its star formation cousin of Orion, the Corona Australis region (containing, at its heart, the Coronet cluster) is one of the nearest and most active regions of ongoing star formation. The Spitzer image shows young stars plus diffuse emission from dust.

  10. Health Occupations Cluster Guide.

    ERIC Educational Resources Information Center

    Oregon State Dept. of Education, Salem.

    Intended to assist the vocational teacher in designing and implementing a cluster program in health occupations, this guide suggests ideas for teaching the specific knowledge and skills that qualify students for entry-level employment in the health occupations field. The knowledge and skills are applicable to 12 occupations: dental assistant;…

  11. FUEL ROD CLUSTERS

    DOEpatents

    Schultz, A.B.

    1959-08-01

    A cluster of nuclear fuel rods and a tubular casing therefor through which a coolant flows in heat-exchange contact with the fuel rods is described. The fuel rcds are held in the casing by virtue of the compressive force exerted between longitudinal ribs of the fuel rcds and internal ribs of the casing or the internal surfaces thereof.

  12. Buckets, Clusters and Dienst

    NASA Technical Reports Server (NTRS)

    Nelson, Michael L.; Maly, Kurt; Shen, Stewart N. T.

    1997-01-01

    In this paper we describe NCSTRL+, a unified, canonical digital library for scientific and technical information (STI). NCSTRL+ is based on the Networked Computer Science Technical Report Library (NCSTRL), a World Wide Web (WWW) accessible digital library (DL) that provides access to over 80 university departments and laboratories. NCSTRL+ implements two new technologies: cluster functionality and publishing "buckets." We have extended the Dienst protocol, the protocol underlying NCSTRL, to provide the ability to "cluster" independent collections into a logically centralized digital library based upon subject category classification, type of organization, and genres of material. The concept of "buckets" provides a mechanism for publishing and managing logically linked entities with multiple data formats. The NCSTRL+ prototype DL contains the holdings of NCSTRL and the NASA Technical Report Server (NTRS). The prototype demonstrates the feasibility of publishing into a multi-cluster DL, searching across clusters, and storing and presenting buckets of information. We show that the overhead for these additional capabilities is minimal to both the author and the user when compared to the equivalent process within NCSTRL.

  13. Detecting alternative graph clusterings.

    PubMed

    Mandala, Supreet; Kumara, Soundar; Yao, Tao

    2012-07-01

    The problem of graph clustering or community detection has enjoyed a lot of attention in complex networks literature. A quality function, modularity, quantifies the strength of clustering and on maximization yields sensible partitions. However, in most real world networks, there are an exponentially large number of near-optimal partitions with some being very different from each other. Therefore, picking an optimal clustering among the alternatives does not provide complete information about network topology. To tackle this problem, we propose a graph perturbation scheme which can be used to identify an ensemble of near-optimal and diverse clusterings. We establish analytical properties of modularity function under the perturbation which ensures diversity. Our approach is algorithm independent and therefore can leverage any of the existing modularity maximizing algorithms. We numerically show that our methodology can systematically identify very different partitions on several existing data sets. The knowledge of diverse partitions sheds more light into the topological organization and helps gain a more complete understanding of the underlying complex network.

  14. Construction Cluster Skills Standards.

    ERIC Educational Resources Information Center

    DePaul Univ., Chicago, IL. Built Environment Partnership.

    Twelve construction cluster skill standards and associated benchmarks were developed as part of a federally funded school-to-work initiative that included the following parties: the Chicago Public Schools; City Colleges of Chicago; and business, labor, and community organizations. The standards, which include core academic, generic workplace…

  15. PVM Support for Clusters

    NASA Technical Reports Server (NTRS)

    Springer, P.

    2000-01-01

    The latest version of PVM (3.4.3) now contains support for a PC cluster running Linux, also known as a Beowulf system. A PVM user of a computer outside the Beowulf system can add the Beowulf as a single machine.

  16. Curriculum Guide Construction Cluster.

    ERIC Educational Resources Information Center

    Kline, Ken

    As part of a model construction cluster curriculum development project, this guide was developed and implemented in the Beaverton (Oregon) School District. The curriculum guide contains 16 units covering the following topics: introduction to construction jobs; safety and first aid; blueprint readings; basic mathematics; site work; framing; roofing…

  17. PDMS embedded Ag clusters: Coalescence and cluster-matrix interaction

    NASA Astrophysics Data System (ADS)

    Roese, S.; Engemann, D.; Hoffmann, S.; Latussek, K.; Sternemann, C.; Hövel, H.

    2016-05-01

    Polydimethylsiloxane (PDMS) has proven to be a suitable embedding medium for silver clusters to prevent aggregation. In order to investigate the influence of the PDMS on the electronic and local atomic structure of the clusters the measurement of x-ray absorption near edge structure (XANES) spectra for different coverages of silver clusters in PDMS and calculations of corresponding XANES spectra have been performed. The coalescence process and the cluster-PDMS interaction were investigated with XANES.

  18. Femtosecond dynamics of cluster expansion

    NASA Astrophysics Data System (ADS)

    Gao, Xiaohui; Wang, Xiaoming; Shim, Bonggu; Arefiev, Alexey; Tushentsov, Mikhail; Breizman, Boris; Downer, Mike

    2010-03-01

    Noble gas clusters irradiated by intense ultrafast laser expand quickly and become typical plasma in picosecond time scale. During the expansion, the clustered plasma demonstrates unique optical properties such as strong absorption and positive contribution to the refractive index. Here we studied cluster expansion dynamics by fs-time-resolved refractive index and absorption measurements in cluster gas jets after ionization and heating by an intense pump pulse. The refractive index measured by frequency domain interferometry (FDI) shows the transient positive peak of refractive index due to clustered plasma. By separating it from the negative contribution of the monomer plasma, we are able to determine the cluster fraction. The absorption measured by a delayed probe shows the contribution from clusters of various sizes. The plasma resonances in the cluster explain the enhancement of the absorption in our isothermal expanding cluster model. The cluster size distribution can be determined. A complete understanding of the femtosecond dynamics of cluster expansion is essential in the accurate interpretation and control of laser-cluster experiments such as phase-matched harmonic generation in cluster medium.

  19. The Rotation of Galaxy Clusters

    NASA Astrophysics Data System (ADS)

    Tovmassian, H. M.

    2015-09-01

    The method for detection of the galaxy cluster rotation based on the study of distribution of member galaxies with velocities lower and higher than the cluster mean velocity over the cluster image is proposed. The search for rotation is made for flat clusters with a/b > 1.8 and BMI type clusters which are expected to be rotating. For comparison there were studied also round clusters and clusters of NBMI type, the second by brightness galaxy, which does not differ significantly from the cluster cD galaxy. Seventeen out of studied 65 clusters are found to be rotating. It was found that the detection rate is sufficiently high for flat clusters, over 60%, and clusters of BMI type with dominant cD galaxy, ≈ 35% . The obtained results show that clusters were formed from the huge primordial gas clouds and preserved the rotation of the primordial clouds, unless they did not experience mergings with other clusters and groups of galaxies, as a result of which the rotation was prevented.

  20. Choosing the Number of Clusters in K-Means Clustering

    ERIC Educational Resources Information Center

    Steinley, Douglas; Brusco, Michael J.

    2011-01-01

    Steinley (2007) provided a lower bound for the sum-of-squares error criterion function used in K-means clustering. In this article, on the basis of the lower bound, the authors propose a method to distinguish between 1 cluster (i.e., a single distribution) versus more than 1 cluster. Additionally, conditional on indicating there are multiple…