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  • Binding Sites  (687)
  • nitrogen
  • American Association for the Advancement of Science (AAAS)  (687)
  • Springer  (593)
  • American Institute of Physics (AIP)
  • 1995-1999  (662)
  • 1990-1994  (525)
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  • American Association for the Advancement of Science (AAAS)  (687)
  • Springer  (593)
  • American Institute of Physics (AIP)
  • Wiley-Blackwell  (12)
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  • 1
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1999-01-05
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Adams, M W -- Stiefel, E I -- New York, N.Y. -- Science. 1998 Dec 4;282(5395):1842-3.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Biochemistry and Molecular Biology, University of Georgia, Athens, GA 30602, USA. adams@bmb.uga.edu〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/9874636" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Binding Sites ; Carbon Monoxide/chemistry ; Clostridium/*enzymology ; Crystallography, X-Ray ; Cyanides/chemistry ; Humans ; Hydrogen/*metabolism ; Hydrogenase/*chemistry/*metabolism ; Iron/chemistry ; Ligands ; Oxidation-Reduction ; Pyruvic Acid/metabolism
    Print ISSN: 0036-8075
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  • 2
    Publication Date: 1999-10-09
    Description: The Yersinia pseudotuberculosis invasin protein promotes bacterial entry by binding to host cell integrins with higher affinity than natural substrates such as fibronectin. The 2.3 angstrom crystal structure of the invasin extracellular region reveals five domains that form a 180 angstrom rod with structural similarities to tandem fibronectin type III domains. The integrin-binding surfaces of invasin and fibronectin include similarly located key residues, but in the context of different folds and surface shapes. The structures of invasin and fibronectin provide an example of convergent evolution, in which invasin presents an optimized surface for integrin binding, in comparison with host substrates.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Hamburger, Z A -- Brown, M S -- Isberg, R R -- Bjorkman, P J -- New York, N.Y. -- Science. 1999 Oct 8;286(5438):291-5.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Division of Biology 156-29, Howard Hughes Medical Institute, California Institute of Technology, Pasadena, CA 91125, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/10514372" target="_blank"〉PubMed〈/a〉
    Keywords: *Adhesins, Bacterial ; Amino Acid Sequence ; Bacterial Proteins/*chemistry/metabolism ; Binding Sites ; Crystallography, X-Ray ; Evolution, Molecular ; Fibronectins/chemistry/metabolism ; Hydrogen Bonding ; Integrins/*metabolism ; Ligands ; Models, Molecular ; Protein Binding ; Protein Conformation ; Protein Folding ; Protein Structure, Secondary ; Yersinia pseudotuberculosis/*chemistry/metabolism
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  • 3
    Publication Date: 1999-09-25
    Description: The flow of information from calcium-mobilizing receptors to nuclear factor of activated T cells (NFAT)-dependent genes is critically dependent on interaction between the phosphatase calcineurin and the transcription factor NFAT. A high-affinity calcineurin-binding peptide was selected from combinatorial peptide libraries based on the calcineurin docking motif of NFAT. This peptide potently inhibited NFAT activation and NFAT-dependent expression of endogenous cytokine genes in T cells, without affecting the expression of other cytokines that require calcineurin but not NFAT. Substitution of the optimized peptide sequence into the natural calcineurin docking site increased the calcineurin responsiveness of NFAT. Compounds that interfere selectively with the calcineurin-NFAT interaction without affecting calcineurin phosphatase activity may be useful as therapeutic agents that are less toxic than current drugs.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Aramburu, J -- Yaffe, M B -- Lopez-Rodriguez, C -- Cantley, L C -- Hogan, P G -- Rao, A -- R01 AI 40127/AI/NIAID NIH HHS/ -- R01 GM056203/GM/NIGMS NIH HHS/ -- R01 HL 03601/HL/NHLBI NIH HHS/ -- R43 AI 43726/AI/NIAID NIH HHS/ -- etc. -- New York, N.Y. -- Science. 1999 Sep 24;285(5436):2129-33.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Pathology, Harvard Medical School, Boston, MA 02115, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/10497131" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acid Sequence ; Binding Sites ; Calcineurin/*metabolism ; Calcineurin Inhibitors ; Cell Nucleus/metabolism ; Cyclosporine/pharmacology ; Cytokines/biosynthesis/genetics ; DNA-Binding Proteins/*antagonists & inhibitors/chemistry/metabolism ; Gene Expression Regulation ; Genes, Reporter ; HeLa Cells ; Humans ; Immunosuppressive Agents/chemistry/metabolism/*pharmacology ; Jurkat Cells ; Molecular Sequence Data ; NFATC Transcription Factors ; *Nuclear Proteins ; Oligopeptides/chemistry/metabolism/*pharmacology ; Peptide Library ; Peptides/chemistry/metabolism/*pharmacology ; Phosphorylation ; Recombinant Fusion Proteins/metabolism ; T-Lymphocytes/*drug effects/immunology ; Transcription Factors/*antagonists & inhibitors/chemistry/metabolism ; Transfection
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  • 4
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1999-05-18
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Landick, R -- New York, N.Y. -- Science. 1999 Apr 23;284(5414):598-9.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Bacteriology, University of Wisconsin-Madison, Madison, WI 53706, USA. landick@macc.wisc.edu〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/10328742" target="_blank"〉PubMed〈/a〉
    Keywords: Base Pairing ; Binding Sites ; DNA/chemistry/*metabolism ; DNA-Directed RNA Polymerases/genetics/*metabolism ; Escherichia coli/enzymology/genetics ; Gene Expression Regulation ; Humans ; Models, Genetic ; Mutation ; Nucleic Acid Conformation ; Oligodeoxyribonucleotides, Antisense/chemistry/metabolism ; RNA, Messenger/chemistry/*metabolism ; *Terminator Regions, Genetic ; *Transcription, Genetic ; Viral Proteins/metabolism
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  • 5
    Publication Date: 1999-11-27
    Description: X-ray crystal structures of three species related to the oxidative half of the reaction of the copper-containing quinoprotein amine oxidase from Escherichia coli have been determined. Crystals were freeze-trapped either anaerobically or aerobically after exposure to substrate, and structures were determined to resolutions between 2.1 and 2.4 angstroms. The oxidation state of the quinone cofactor was investigated by single-crystal spectrophotometry. The structures reveal the site of bound dioxygen and the proton transfer pathways involved in oxygen reduction. The quinone cofactor is regenerated from the iminoquinone intermediate by hydrolysis involving Asp383, the catalytic base in the reductive half-reaction. Product aldehyde inhibits the hydrolysis, making release of product the rate-determining step of the reaction in the crystal.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Wilmot, C M -- Hajdu, J -- McPherson, M J -- Knowles, P F -- Phillips, S E -- New York, N.Y. -- Science. 1999 Nov 26;286(5445):1724-8.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Astbury Centre for Structural Molecular Biology, School of Biochemistry and Molecular Biology, University of Leeds, Leeds LS2 9JT, UK.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/10576737" target="_blank"〉PubMed〈/a〉
    Keywords: Aerobiosis ; Amine Oxidase (Copper-Containing)/*chemistry/*metabolism ; Anaerobiosis ; Aspartic Acid/chemistry/metabolism ; Binding Sites ; Catalysis ; Copper/*metabolism ; Crystallography, X-Ray ; Dihydroxyphenylalanine/*analogs & derivatives/chemistry/metabolism ; Dimerization ; Electrons ; Escherichia coli/enzymology ; Hydrogen Bonding ; Nitric Oxide/metabolism ; Oxidation-Reduction ; Oxygen/*metabolism ; Phenethylamines/metabolism ; Protein Conformation ; Protein Structure, Secondary ; Protons ; Spectrum Analysis
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  • 6
    Publication Date: 1999-09-25
    Description: The 7.8 angstrom crystal structure of the 70S ribosome reveals a discrete double-helical bridge (B4) that projects from the 50S subunit, making contact with the 30S subunit. Preliminary modeling studies localized its contact site, near the bottom of the platform, to the binding site for ribosomal protein S15. Directed hydroxyl radical probing from iron(II) tethered to S15 specifically cleaved nucleotides in the 715 loop of domain II of 23S ribosomal RNA, one of the known sites in 23S ribosomal RNA that are footprinted by the 30S subunit. Reconstitution studies show that protection of the 715 loop, but none of the other 30S-dependent protections, is correlated with the presence of S15 in the 30S subunit. The 715 loop is specifically protected by binding free S15 to 50S subunits. Moreover, the previously determined structure of a homologous stem-loop from U2 small nuclear RNA fits closely to the electron density of the bridge.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Culver, G M -- Cate, J H -- Yusupova, G Z -- Yusupov, M M -- Noller, H F -- 1F32GM18065-01/GM/NIGMS NIH HHS/ -- GM-17129/GM/NIGMS NIH HHS/ -- GM-59140/GM/NIGMS NIH HHS/ -- New York, N.Y. -- Science. 1999 Sep 24;285(5436):2133-6.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Center for Molecular Biology of RNA, Sinsheimer Laboratories, University of California, Santa Cruz, CA 95064, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/10497132" target="_blank"〉PubMed〈/a〉
    Keywords: Bacterial Proteins/chemistry/metabolism ; Binding Sites ; Crystallography, X-Ray ; Escherichia coli/chemistry ; Hydroxyl Radical ; Nucleic Acid Conformation ; Protein Conformation ; RNA, Bacterial/*chemistry/metabolism ; RNA, Ribosomal, 23S/*chemistry/metabolism ; RNA, Small Nuclear/chemistry/metabolism ; Ribosomal Proteins/chemistry/*metabolism ; Ribosomes/*chemistry/metabolism/ultrastructure ; Thermus thermophilus/chemistry
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  • 7
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1999-12-28
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Wilson, I A -- New York, N.Y. -- Science. 1999 Dec 3;286(5446):1867-8.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Molecular Biology and Skaggs Institute for Chemical Biology, The Scripps Research Institute, La Jolla, CA 92037, USA. wilson@scripps.edu〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/10610577" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Antigens/*chemistry/immunology/metabolism ; Binding Sites ; CD4-Positive T-Lymphocytes/immunology/metabolism ; CD8-Positive T-Lymphocytes/immunology/metabolism ; Crystallography, X-Ray ; Histocompatibility Antigens Class I/chemistry/immunology/metabolism ; Histocompatibility Antigens Class II/*chemistry/immunology/metabolism ; Mice ; Models, Molecular ; Peptides/chemistry/immunology/metabolism ; Protein Binding ; Protein Conformation ; Protein Structure, Secondary ; Receptors, Antigen, T-Cell, alpha-beta/*chemistry/immunology/metabolism
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  • 8
    Publication Date: 1999-08-28
    Description: Class II transactivator (CIITA) is a global transcriptional coactivator of human leukocyte antigen-D (HLA-D) genes. CIITA contains motifs similar to guanosine triphosphate (GTP)-binding proteins. This report shows that CIITA binds GTP, and mutations in these motifs decrease its GTP-binding and transactivation activity. Substitution of these motifs with analogous sequences from Ras restores CIITA function. CIITA exhibits little GTPase activity, yet mutations in CIITA that confer GTPase activity reduce transcriptional activity. GTP binding by CIITA correlates with nuclear import. Thus, unlike other GTP-binding proteins, CIITA is involved in transcriptional activation that uses GTP binding to facilitate its own nuclear import.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Harton, J A -- Cressman, D E -- Chin, K C -- Der, C J -- Ting, J P -- AI29564/AI/NIAID NIH HHS/ -- AI41751/AI/NIAID NIH HHS/ -- AI45580/AI/NIAID NIH HHS/ -- etc. -- New York, N.Y. -- Science. 1999 Aug 27;285(5432):1402-5.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Lineberger Comprehensive Cancer Center, University of North Carolina-Chapel Hill, Chapel Hill, NC 27599, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/10464099" target="_blank"〉PubMed〈/a〉
    Keywords: Adenosine Triphosphate/metabolism ; Animals ; Binding Sites ; COS Cells ; Cell Line ; Cell Nucleus/*metabolism ; GTP-Binding Proteins/chemistry/genetics/*metabolism ; *Genes, MHC Class II ; Guanosine Triphosphate/*metabolism ; HLA-DR Antigens/genetics ; Humans ; Mutation ; *Nuclear Proteins ; Promoter Regions, Genetic ; Temperature ; Trans-Activators/chemistry/genetics/*metabolism ; Transcription Factors/metabolism ; *Transcriptional Activation
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  • 9
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1999-04-30
    Description: The ability of the GroEL chaperonin to unfold a protein trapped in a misfolded condition was detected and studied by hydrogen exchange. The GroEL-induced unfolding of its substrate protein is only partial, requires the complete chaperonin system, and is accomplished within the 13 seconds required for a single system turnover. The binding of nucleoside triphosphate provides the energy for a single unfolding event; multiple turnovers require adenosine triphosphate hydrolysis. The substrate protein is released on each turnover even if it has not yet refolded to the native state. These results suggest that GroEL helps partly folded but blocked proteins to fold by causing them first to partially unfold. The structure of GroEL seems well suited to generate the nonspecific mechanical stretching force required for forceful protein unfolding.〈br /〉〈br /〉〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3427652/" target="_blank"〉〈img src="https://static.pubmed.gov/portal/portal3rc.fcgi/4089621/img/3977009" border="0"〉〈/a〉   〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3427652/" target="_blank"〉This paper as free author manuscript - peer-reviewed and accepted for publication〈/a〉〈br /〉〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Shtilerman, M -- Lorimer, G H -- Englander, S W -- GM31847/GM/NIGMS NIH HHS/ -- R01 GM031847/GM/NIGMS NIH HHS/ -- New York, N.Y. -- Science. 1999 Apr 30;284(5415):822-5.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉The Johnson Research Foundation, Department of Biochemistry and Biophysics, University of Pennsylvania School of Medicine, Philadelphia, PA 19104, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/10221918" target="_blank"〉PubMed〈/a〉
    Keywords: Adenosine Triphosphate/metabolism ; Adenylyl Imidodiphosphate/metabolism ; Binding Sites ; Chaperonin 10/chemistry/metabolism/physiology ; Chaperonin 60/chemistry/metabolism/*physiology ; Hydrogen/chemistry/metabolism ; Models, Molecular ; Protein Binding ; Protein Conformation ; *Protein Folding ; Protein Structure, Secondary ; Ribulose-Bisphosphate Carboxylase/*chemistry/metabolism
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  • 10
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1999-08-24
    Description: Clathrin-mediated endocytosis is initiated by the recruitment of the clathrin adaptor protein AP-2 to the plasma membrane where the membrane protein synaptotagmin is thought to act as a docking site. AP-2 also interacts with endocytic motifs present in other cargo proteins. Peptides with a tyrosine-based endocytic motif stimulated binding of AP-2 to synaptotagmin and enhanced AP-2 recruitment to the plasma membrane of neuronal and non-neuronal cells. This suggests a mechanism by which nucleation of clathrin-coated pits is stimulated by the loading of cargo proteins.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Haucke, V -- De Camilli, P -- CA46128/CA/NCI NIH HHS/ -- NS36252/NS/NINDS NIH HHS/ -- New York, N.Y. -- Science. 1999 Aug 20;285(5431):1268-71.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Cell Biology and Howard Hughes Medical Institute, Yale University School of Medicine, 295 Congress Avenue, New Haven, CT 06510, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/10455054" target="_blank"〉PubMed〈/a〉
    Keywords: Adaptor Protein Complex alpha Subunits ; Adaptor Proteins, Vesicular Transport ; Animals ; Binding Sites ; CHO Cells ; *Calcium-Binding Proteins ; Cattle ; Cell Membrane/metabolism ; Clathrin/*metabolism ; Coated Pits, Cell-Membrane/*metabolism ; Cricetinae ; *Endocytosis ; Membrane Glycoproteins/chemistry/*metabolism ; Membrane Proteins/*metabolism ; Nerve Tissue Proteins/chemistry/*metabolism ; Neurons/metabolism ; Oligopeptides/chemistry/metabolism/*pharmacology ; Phospholipase D/metabolism ; Protein Binding ; Rats ; Recombinant Fusion Proteins/metabolism ; Synaptic Membranes/*metabolism ; Synaptotagmins ; Tyrosine/chemistry
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  • 11
    Publication Date: 1999-07-31
    Description: Many immune receptors are composed of separate ligand-binding and signal-transducing subunits. In natural killer (NK) and T cells, DAP10 was identified as a cell surface adaptor protein in an activating receptor complex with NKG2D, a receptor for the stress-inducible and tumor-associated major histocompatibility complex molecule MICA. Within the DAP10 cytoplasmic domain, an Src homology 2 (SH2) domain-binding site was capable of recruiting the p85 subunit of the phosphatidylinositol 3-kinase (PI 3-kinase), providing for NKG2D-dependent signal transduction. Thus, NKG2D-DAP10 receptor complexes may activate NK and T cell responses against MICA-bearing tumors.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Wu, J -- Song, Y -- Bakker, A B -- Bauer, S -- Spies, T -- Lanier, L L -- Phillips, J H -- AI30581/AI/NIAID NIH HHS/ -- New York, N.Y. -- Science. 1999 Jul 30;285(5428):730-2.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉DNAX Research Institute, 901 California Avenue, Palo Alto, CA 94304, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/10426994" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acid Sequence ; Animals ; Binding Sites ; Cell Line ; Cytotoxicity, Immunologic ; Humans ; Killer Cells, Natural/*immunology/metabolism ; Ligands ; *Lymphocyte Activation ; Membrane Proteins/chemistry/genetics/*metabolism ; Mice ; Molecular Sequence Data ; NK Cell Lectin-Like Receptor Subfamily K ; Neoplasms/immunology ; Phosphatidylinositol 3-Kinases/metabolism ; Phosphorylation ; Phosphotyrosine/metabolism ; Receptors, Immunologic/chemistry/genetics/*metabolism ; Receptors, Natural Killer Cell ; Signal Transduction ; T-Lymphocytes/*immunology/metabolism ; Tumor Cells, Cultured ; src Homology Domains
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  • 12
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1999-10-16
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Liljas, A -- New York, N.Y. -- Science. 1999 Sep 24;285(5436):2077-8.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Molecular Biology, Center for Chemistry and Chemical Engineering, University of Lund, Lund, Sweden. anders.liljas@mbfys.lu.se〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/10523206" target="_blank"〉PubMed〈/a〉
    Keywords: Anticodon ; Bacterial Proteins/biosynthesis/chemistry ; Binding Sites ; Codon ; Cryoelectron Microscopy ; Crystallography, X-Ray ; Nucleic Acid Conformation ; Peptide Elongation Factors/metabolism ; Protein Conformation ; RNA, Bacterial/chemistry/metabolism ; RNA, Ribosomal/chemistry ; RNA, Transfer/chemistry/metabolism ; Ribosomal Proteins/chemistry ; Ribosomes/*chemistry/*physiology/ultrastructure
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  • 13
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1999-07-10
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Hederstedt, L -- New York, N.Y. -- Science. 1999 Jun 18;284(5422):1941-2.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Microbiology, Lund University, Lund, Sweden. Lars.Hederstedt@mikrbiol.lu.se〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/10400536" target="_blank"〉PubMed〈/a〉
    Keywords: Anaerobiosis ; Bacillus subtilis/enzymology ; Binding Sites ; Cell Membrane/enzymology ; Crystallography, X-Ray ; Dimerization ; Electron Transport ; *Energy Metabolism ; Escherichia coli/*enzymology ; Evolution, Molecular ; Fumarates/metabolism ; Mitochondria/enzymology ; Oxidation-Reduction ; Oxygen Consumption ; Protein Conformation ; Protein Structure, Secondary ; Succinate Dehydrogenase/*chemistry/*metabolism ; Succinic Acid/metabolism
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  • 14
    Publication Date: 1999-08-14
    Description: Isoleucyl-transfer RNA (tRNA) synthetase (IleRS) joins Ile to tRNA(Ile) at its synthetic active site and hydrolyzes incorrectly acylated amino acids at its editing active site. The 2.2 angstrom resolution crystal structure of Staphylococcus aureus IleRS complexed with tRNA(Ile) and Mupirocin shows the acceptor strand of the tRNA(Ile) in the continuously stacked, A-form conformation with the 3' terminal nucleotide in the editing active site. To position the 3' terminus in the synthetic active site, the acceptor strand must adopt the hairpinned conformation seen in tRNA(Gln) complexed with its synthetase. The amino acid editing activity of the IleRS may result from the incorrect products shuttling between the synthetic and editing active sites, which is reminiscent of the editing mechanism of DNA polymerases.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Silvian, L F -- Wang, J -- Steitz, T A -- GM22778/GM/NIGMS NIH HHS/ -- New York, N.Y. -- Science. 1999 Aug 13;285(5430):1074-7.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Molecular Biophysics, Yale University, and Howard Hughes Medical Institute, New Haven, CT 06520-8114, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/10446055" target="_blank"〉PubMed〈/a〉
    Keywords: Acylation ; Adenosine Monophosphate/analogs & derivatives/metabolism ; Amino Acids/metabolism ; Binding Sites ; Crystallography, X-Ray ; DNA-Directed DNA Polymerase/metabolism ; Glutamate-tRNA Ligase/chemistry/metabolism ; Isoleucine/metabolism ; Isoleucine-tRNA Ligase/*chemistry/*metabolism ; Models, Molecular ; Mupirocin/chemistry/*metabolism ; Nucleic Acid Conformation ; Oligopeptides/metabolism ; Protein Conformation ; Protein Structure, Secondary ; RNA, Transfer, Gln/chemistry/metabolism ; RNA, Transfer, Ile/*chemistry/*metabolism ; Staphylococcus aureus/enzymology ; Substrate Specificity
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  • 15
    Publication Date: 1999-04-16
    Description: Mutation of the VHL tumor suppressor is associated with the inherited von Hippel-Lindau (VHL) cancer syndrome and the majority of kidney cancers. VHL binds the ElonginC-ElonginB complex and regulates levels of hypoxia-inducible proteins. The structure of the ternary complex at 2.7 angstrom resolution shows two interfaces, one between VHL and ElonginC and another between ElonginC and ElonginB. Tumorigenic mutations frequently occur in a 35-residue domain of VHL responsible for ElonginC binding. A mutational patch on a separate domain of VHL indicates a second macromolecular binding site. The structure extends the similarities to the SCF (Skp1-Cul1-F-box protein) complex that targets proteins for degradation, supporting the hypothesis that VHL may function in an analogous pathway.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Stebbins, C E -- Kaelin, W G Jr -- Pavletich, N P -- New York, N.Y. -- Science. 1999 Apr 16;284(5413):455-61.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Biochemistry and Structural Biology, Joan and Sanford I. Weill Graduate School of Medical Sciences, Cornell University, New York, NY 10021, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/10205047" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acid Sequence ; Binding Sites ; Cell Cycle Proteins/chemistry/metabolism ; Cloning, Molecular ; Crystallography, X-Ray ; *Genes, Tumor Suppressor ; Humans ; Hydrogen Bonding ; *Ligases ; Models, Molecular ; Molecular Sequence Data ; Mutation ; Mutation, Missense ; Neoplasms/genetics ; Protein Conformation ; Protein Folding ; Protein Structure, Secondary ; Proteins/*chemistry/genetics/metabolism ; S-Phase Kinase-Associated Proteins ; Surface Properties ; Transcription Factors/*chemistry/metabolism ; *Tumor Suppressor Proteins ; *Ubiquitin-Protein Ligases ; Von Hippel-Lindau Tumor Suppressor Protein ; von Hippel-Lindau Disease/*genetics
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  • 16
    Publication Date: 1999-12-30
    Description: The Smad proteins mediate transforming growth factor-beta (TGFbeta) signaling from the transmembrane serine-threonine receptor kinases to the nucleus. The Smad anchor for receptor activation (SARA) recruits Smad2 to the TGFbeta receptors for phosphorylation. The crystal structure of a Smad2 MH2 domain in complex with the Smad-binding domain (SBD) of SARA has been determined at 2.2 angstrom resolution. SARA SBD, in an extended conformation comprising a rigid coil, an alpha helix, and a beta strand, interacts with the beta sheet and the three-helix bundle of Smad2. Recognition between the SARA rigid coil and the Smad2 beta sheet is essential for specificity, whereas interactions between the SARA beta strand and the Smad2 three-helix bundle contribute significantly to binding affinity. Comparison of the structures between Smad2 and a comediator Smad suggests a model for how receptor-regulated Smads are recognized by the type I receptors.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Wu, G -- Chen, Y G -- Ozdamar, B -- Gyuricza, C A -- Chong, P A -- Wrana, J L -- Massague, J -- Shi, Y -- CA85171/CA/NCI NIH HHS/ -- New York, N.Y. -- Science. 2000 Jan 7;287(5450):92-7.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Molecular Biology, Princeton University, Lewis Thomas Laboratory, Princeton, NJ 08544, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/10615055" target="_blank"〉PubMed〈/a〉
    Keywords: *Activin Receptors, Type I ; Amino Acid Sequence ; Binding Sites ; Carrier Proteins/*chemistry/*metabolism ; Crystallography, X-Ray ; DNA-Binding Proteins/*chemistry/genetics/*metabolism ; Hydrogen Bonding ; Models, Molecular ; Molecular Sequence Data ; Mutation ; Phosphorylation ; Point Mutation ; Protein Conformation ; Protein Structure, Secondary ; Protein Structure, Tertiary ; Protein-Serine-Threonine Kinases/chemistry/genetics/metabolism ; Receptors, Transforming Growth Factor beta/chemistry/genetics/metabolism ; Recombinant Fusion Proteins/chemistry/metabolism ; Signal Transduction ; Smad2 Protein ; Trans-Activators/*chemistry/genetics/*metabolism ; Zinc Fingers
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  • 17
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1999-10-09
    Description: For mapping energetic interactions in proteins, a technique was developed that uses evolutionary data for a protein family to measure statistical interactions between amino acid positions. For the PDZ domain family, this analysis predicted a set of energetically coupled positions for a binding site residue that includes unexpected long-range interactions. Mutational studies confirm these predictions, demonstrating that the statistical energy function is a good indicator of thermodynamic coupling in proteins. Sets of interacting residues form connected pathways through the protein fold that may be the basis for efficient energy conduction within proteins.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Lockless, S W -- Ranganathan, R -- New York, N.Y. -- Science. 1999 Oct 8;286(5438):295-9.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Howard Hughes Medical Institute and Department of Pharmacology, University of Texas Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, TX 75235-9050, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/10514373" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acid Sequence ; Amino Acids/chemistry/metabolism ; Binding Sites ; Conserved Sequence ; *Evolution, Molecular ; Models, Molecular ; Mutation ; Probability ; Protein Binding ; Protein Conformation ; Protein Folding ; Protein Structure, Tertiary ; Proteins/*chemistry/*metabolism ; Recombinant Fusion Proteins/chemistry/metabolism ; Sequence Alignment ; Statistics as Topic ; Thermodynamics
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  • 18
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1999-10-03
    Description: Ribozymes use a number of the same catalytic strategies as protein enzymes. However, general base catalysis by a ribozyme has not been demonstrated. In the hepatitis delta virus antigenomic ribozyme, imidazole buffer rescued activity of a mutant with a cytosine-76 (C76) to uracil substitution. In addition, a C76 to adenine substitution reduced the apparent pKa (where Ka is the acid constant) of the self-cleavage reaction by an amount consistent with differences in the pKa values of these two side chains. These results suggest that, in the wild-type ribozyme, C76 acts as a general base. This finding has implications for potential catalytic functions of conserved cytosines and adenines in other ribozymes and in ribonuclear proteins with enzymatic activity.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Perrotta, A T -- Shih, I -- Been, M D -- GM47322/GM/NIGMS NIH HHS/ -- New York, N.Y. -- Science. 1999 Oct 1;286(5437):123-6.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Biochemistry, Box 3711, Duke University Medical Center, Durham, NC 27710 USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/10506560" target="_blank"〉PubMed〈/a〉
    Keywords: Binding Sites ; Catalysis ; Cytosine/*chemistry/metabolism/pharmacology ; Hepatitis Delta Virus/chemistry/*enzymology ; Hydrogen-Ion Concentration ; Imidazoles/chemistry/*metabolism/pharmacology ; Magnesium Chloride/pharmacology ; Manganese/pharmacology ; Mutagenesis ; Point Mutation ; Protons ; Pyrazoles/pharmacology ; RNA, Catalytic/*chemistry/genetics/*metabolism ; Temperature
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  • 19
    Publication Date: 1999-11-13
    Description: The E6AP ubiquitin-protein ligase (E3) mediates the human papillomavirus-induced degradation of the p53 tumor suppressor in cervical cancer and is mutated in Angelman syndrome, a neurological disorder. The crystal structure of the catalytic hect domain of E6AP reveals a bilobal structure with a broad catalytic cleft at the junction of the two lobes. The cleft consists of conserved residues whose mutation interferes with ubiquitin-thioester bond formation and is the site of Angelman syndrome mutations. The crystal structure of the E6AP hect domain bound to the UbcH7 ubiquitin-conjugating enzyme (E2) reveals the determinants of E2-E3 specificity and provides insights into the transfer of ubiquitin from the E2 to the E3.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Huang, L -- Kinnucan, E -- Wang, G -- Beaudenon, S -- Howley, P M -- Huibregtse, J M -- Pavletich, N P -- New York, N.Y. -- Science. 1999 Nov 12;286(5443):1321-6.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Cellular Biochemistry and Biophysics Program, Howard Hughes Medical Institute, Memorial Sloan-Kettering Cancer Center, New York, NY 10021, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/10558980" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acid Sequence ; Angelman Syndrome/genetics ; Binding Sites ; Catalytic Domain ; Conserved Sequence ; Crystallography, X-Ray ; Cysteine/chemistry ; Humans ; Ligases/*chemistry/*metabolism ; Models, Molecular ; Molecular Sequence Data ; Mutation ; Protein Conformation ; Protein Structure, Secondary ; Substrate Specificity ; Ubiquitin-Conjugating Enzymes ; Ubiquitin-Protein Ligases ; Ubiquitins/*metabolism
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  • 20
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1999-07-10
    Description: Endocytosis is crucial for an array of cellular functions and can occur through several distinct mechanisms with the capacity to internalize anything from small molecules to entire cells. The clathrin-mediated endocytic pathway has recently received considerable attention because of (i) the identification of an array of molecules that orchestrate the assembly of clathrin-coated vesicles and the selection of the vesicle cargo and (ii) the resolution of structures for a number of these proteins. Together, these data provide an initial three-dimensional framework for understanding the clathrin endocytic machinery.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Marsh, M -- McMahon, H T -- New York, N.Y. -- Science. 1999 Jul 9;285(5425):215-20.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Medical Research Council Laboratory for Molecular Cell Biology and Department of Biochemistry, University College London, Gower Street, London WC1E 6BT, UK. m.marsh@ucl.ac.uk〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/10398591" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Binding Sites ; Calcium-Binding Proteins/chemistry/physiology ; Cell Membrane/ultrastructure ; Clathrin/chemistry/*physiology ; Coated Pits, Cell-Membrane/physiology/ultrastructure ; Coated Vesicles/physiology/ultrastructure ; Dynamins ; *Endocytosis ; GTP Phosphohydrolases/chemistry/physiology ; Membrane Proteins/chemistry/physiology ; Nerve Tissue Proteins/chemistry/physiology ; Phosphoproteins/chemistry/physiology ; Signal Transduction
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  • 21
    Publication Date: 1999-11-24
    Description: Binding of virus particles to specific host cell surface receptors is known to be an obligatory step in infection even though the molecular basis for these interactions is not well characterized. The crystal structure of the adenovirus fiber knob domain in complex with domain I of its human cellular receptor, coxsackie and adenovirus receptor (CAR), is presented here. Surface-exposed loops on knob contact one face of CAR, forming a high-affinity complex. Topology mismatches between interacting surfaces create interfacial solvent-filled cavities and channels that may be targets for antiviral drug therapy. The structure identifies key determinants of binding specificity, which may suggest ways to modify the tropism of adenovirus-based gene therapy vectors.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Bewley, M C -- Springer, K -- Zhang, Y B -- Freimuth, P -- Flanagan, J M -- 1P41 RR12408-01A1/RR/NCRR NIH HHS/ -- New York, N.Y. -- Science. 1999 Nov 19;286(5444):1579-83.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Biology Department, Brookhaven National Laboratory, Upton, NY 11973, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/10567268" target="_blank"〉PubMed〈/a〉
    Keywords: Adenoviruses, Human/chemistry/*metabolism ; Amino Acid Substitution ; Binding Sites ; Capsid/*chemistry/*metabolism ; *Capsid Proteins ; Coxsackie and Adenovirus Receptor-Like Membrane Protein ; Crystallization ; Crystallography, X-Ray ; Hydrogen Bonding ; Models, Molecular ; Mutagenesis ; Protein Binding ; Protein Conformation ; Protein Structure, Secondary ; Receptors, Virus/*chemistry/*metabolism ; Recombinant Proteins/chemistry/metabolism ; Thermodynamics
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  • 22
    Publication Date: 1999-10-09
    Description: Crystal structures of the Asp96 to Asn mutant of the light-driven proton pump bacteriorhodopsin and its M photointermediate produced by illumination at ambient temperature have been determined to 1.8 and 2.0 angstroms resolution, respectively. The trapped photoproduct corresponds to the late M state in the transport cycle-that is, after proton transfer to Asp85 and release of a proton to the extracellular membrane surface, but before reprotonation of the deprotonated retinal Schiff base. Its density map describes displacements of side chains near the retinal induced by its photoisomerization to 13-cis,15-anti and an extensive rearrangement of the three-dimensional network of hydrogen-bonded residues and bound water that accounts for the changed pKa values (where Ka is the acid constant) of the Schiff base and Asp85. The structural changes detected suggest the means for conserving energy at the active site and for ensuring the directionality of proton translocation.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Luecke, H -- Schobert, B -- Richter, H T -- Cartailler, J P -- Lanyi, J K -- R01-GM29498/GM/NIGMS NIH HHS/ -- R01-GM56445/GM/NIGMS NIH HHS/ -- R01-GM59970/GM/NIGMS NIH HHS/ -- New York, N.Y. -- Science. 1999 Oct 8;286(5438):255-61.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Molecular Biology and Biochemistry, University of California, Irvine, CA 92697, USA. hudel@uci.edu〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/10514362" target="_blank"〉PubMed〈/a〉
    Keywords: Bacteriorhodopsins/*chemistry/*metabolism ; Binding Sites ; Crystallography, X-Ray ; Cytoplasm/chemistry ; Hydrogen Bonding ; Hydrogen-Ion Concentration ; Ion Transport ; Isomerism ; Light ; Models, Molecular ; Photolysis ; Photons ; Point Mutation ; Protein Conformation ; Protein Structure, Secondary ; Proton Pumps/*chemistry/*metabolism ; Protons ; Retinaldehyde/chemistry/metabolism ; Schiff Bases ; Thermodynamics ; Water
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  • 23
    Publication Date: 1999-05-13
    Description: Insulin elicits a spectrum of biological responses by binding to its cell surface receptor. In a screen for small molecules that activate the human insulin receptor tyrosine kinase, a nonpeptidyl fungal metabolite (L-783,281) was identified that acted as an insulin mimetic in several biochemical and cellular assays. The compound was selective for insulin receptor versus insulin-like growth factor I (IGFI) receptor and other receptor tyrosine kinases. Oral administration of L-783,281 to two mouse models of diabetes resulted in significant lowering in blood glucose levels. These results demonstrate the feasibility of discovering novel insulin receptor activators that may lead to new therapies for diabetes.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Zhang, B -- Salituro, G -- Szalkowski, D -- Li, Z -- Zhang, Y -- Royo, I -- Vilella, D -- Diez, M T -- Pelaez, F -- Ruby, C -- Kendall, R L -- Mao, X -- Griffin, P -- Calaycay, J -- Zierath, J R -- Heck, J V -- Smith, R G -- Moller, D E -- New York, N.Y. -- Science. 1999 May 7;284(5416):974-7.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Molecular Endocrinology, Merck Research Laboratories, R80W250, Post Office Box 2000, Rahway, NJ 07065, USA. bei_zhang@merck.com〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/10320380" target="_blank"〉PubMed〈/a〉
    Keywords: Adenosine Triphosphate/metabolism ; Animals ; Ascomycota/*metabolism ; Binding Sites ; Blood Glucose/metabolism ; CHO Cells ; Cricetinae ; Diabetes Mellitus, Type 2/*drug therapy ; Dose-Response Relationship, Drug ; Drug Evaluation, Preclinical ; Enzyme Activation ; Glucose Tolerance Test ; Hyperglycemia/drug therapy ; Hypoglycemic Agents/chemistry/metabolism/*pharmacology/therapeutic use ; Indoles/chemistry/metabolism/*pharmacology/therapeutic use ; Insulin/blood/metabolism/*pharmacology ; Insulin Receptor Substrate Proteins ; Mice ; Mice, Mutant Strains ; Mice, Obese ; Molecular Mimicry ; Phosphoproteins/metabolism ; Phosphorylation ; Protein Conformation/drug effects ; Receptor, Epidermal Growth Factor/metabolism ; Receptor, IGF Type 1/metabolism ; Receptor, Insulin/chemistry/*metabolism ; Signal Transduction
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  • 24
    Publication Date: 1999-07-31
    Description: Adenylyl cyclase (AC) converts adenosine triphosphate (ATP) to cyclic adenosine monophosphate, a ubiquitous second messenger that regulates many cellular functions. Recent structural studies have revealed much about the structure and function of mammalian AC but have not fully defined its active site or catalytic mechanism. Four crystal structures were determined of the catalytic domains of AC in complex with two different ATP analogs and various divalent metal ions. These structures provide a model for the enzyme-substrate complex and conclusively demonstrate that two metal ions bind in the active site. The similarity of the active site of AC to those of DNA polymerases suggests that the enzymes catalyze phosphoryl transfer by the same two-metal-ion mechanism and likely have evolved from a common ancestor.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Tesmer, J J -- Sunahara, R K -- Johnson, R A -- Gosselin, G -- Gilman, A G -- Sprang, S R -- DK38828/DK/NIDDK NIH HHS/ -- DK46371/DK/NIDDK NIH HHS/ -- GM34497/GM/NIGMS NIH HHS/ -- New York, N.Y. -- Science. 1999 Jul 30;285(5428):756-60.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Howard Hughes Medical Institute, Department of Biochemistry, University of Texas Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, TX 75235-9050, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/10427002" target="_blank"〉PubMed〈/a〉
    Keywords: Adenosine Triphosphate/metabolism ; Adenylyl Cyclase Inhibitors ; Adenylyl Cyclases/chemistry/genetics/*metabolism ; Animals ; Aspartic Acid/metabolism ; Binding Sites ; Catalysis ; Crystallography, X-Ray ; Deoxyadenine Nucleotides/metabolism/pharmacology ; Dideoxynucleotides ; Dimerization ; Enzyme Inhibitors/metabolism ; Hydrogen Bonding ; Ligands ; Magnesium/*metabolism ; Manganese/*metabolism ; Models, Molecular ; Mutation ; Protein Conformation ; Protein Folding ; Rats ; Thionucleotides/metabolism/pharmacology ; Zinc/*metabolism
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  • 25
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1999-09-18
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Mach, B -- New York, N.Y. -- Science. 1999 Aug 27;285(5432):1367.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Genetics and Microbiology, University of Geneva Medical School, Geneva, Switzerland. Bernard.Mach@medecine.unige.ch〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/10490413" target="_blank"〉PubMed〈/a〉
    Keywords: Binding Sites ; Cell Nucleus/metabolism ; DNA-Binding Proteins/metabolism ; GTP-Binding Proteins/chemistry/genetics/*metabolism ; *Gene Expression Regulation ; *Genes, MHC Class II ; Guanosine Triphosphate/*metabolism ; Humans ; Lymphocyte Activation ; Mutation ; *Nuclear Proteins ; Promoter Regions, Genetic ; T-Lymphocytes/immunology ; Trans-Activators/chemistry/genetics/*metabolism ; Transcription Factors/metabolism
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  • 26
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1999-03-26
    Description: Entry of the bacterium Salmonella typhimurium into host cells requires membrane ruffling and rearrangement of the actin cytoskeleton. Here, it is shown that the bacterial protein SipA plays a critical role in this process. SipA binds directly to actin, decreases its critical concentration, and inhibits depolymerization of actin filaments. These activities result in the spatial localization and more pronounced outward extension of the Salmonella-induced membrane ruffles, thereby facilitating bacterial uptake.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Zhou, D -- Mooseker, M S -- Galan, J E -- AI30492/AI/NIAID NIH HHS/ -- DK25387/DK/NIDDK NIH HHS/ -- GM52543/GM/NIGMS NIH HHS/ -- New York, N.Y. -- Science. 1999 Mar 26;283(5410):2092-5.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Section of Microbial Pathogenesis, Boyer Center for Molecular Medicine, Yale School of Medicine, New Haven, CT 06536, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/10092234" target="_blank"〉PubMed〈/a〉
    Keywords: Actins/chemistry/genetics/*metabolism ; Antigens, Bacterial/metabolism ; Bacterial Proteins/chemistry/genetics/*metabolism ; Binding Sites ; Biopolymers ; Cell Membrane/ultrastructure ; HeLa Cells ; Humans ; *Microfilament Proteins ; Microscopy, Fluorescence ; Mutation ; Recombinant Fusion Proteins/metabolism ; Salmonella typhimurium/genetics/metabolism/*pathogenicity ; Signal Transduction ; Vinculin/metabolism
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  • 27
    Publication Date: 1999-11-27
    Description: F0F1, found in mitochondria or bacterial membranes, synthesizes adenosine 5'-triphosphate (ATP) coupling with an electrochemical proton gradient and also reversibly hydrolyzes ATP to form the gradient. An actin filament connected to a c subunit oligomer of F0 was able to rotate by using the energy of ATP hydrolysis. The rotary torque produced by the c subunit oligomer reached about 40 piconewton-nanometers, which is similar to that generated by the gamma subunit in the F1 motor. These results suggest that the gamma and c subunits rotate together during ATP hydrolysis and synthesis. Thus, coupled rotation may be essential for energy coupling between proton transport through F0 and ATP hydrolysis or synthesis in F1.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Sambongi, Y -- Iko, Y -- Tanabe, M -- Omote, H -- Iwamoto-Kihara, A -- Ueda, I -- Yanagida, T -- Wada, Y -- Futai, M -- New York, N.Y. -- Science. 1999 Nov 26;286(5445):1722-4.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Division of Biological Sciences, Institute of Scientific and Industrial Research, Osaka University, CREST (Core Research for Evolutional Science and Technology) of Japan Science and Technology Corporation, Ibaraki, Osaka 567-0047, Japan.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/10576736" target="_blank"〉PubMed〈/a〉
    Keywords: Actins/chemistry/metabolism ; Adenosine Triphosphate/*metabolism ; Binding Sites ; Biotinylation ; Energy Transfer ; Enzymes, Immobilized ; Escherichia coli/enzymology ; Hydrolysis ; Molecular Motor Proteins/*chemistry/*metabolism ; Proton-Motive Force ; Proton-Translocating ATPases/*chemistry/*metabolism ; Uncoupling Agents/metabolism/pharmacology ; Venturicidins/pharmacology ; Video Recording
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  • 28
    Publication Date: 1999-06-12
    Description: The editing enzyme double-stranded RNA adenosine deaminase includes a DNA binding domain, Zalpha, which is specific for left-handed Z-DNA. The 2.1 angstrom crystal structure of Zalpha complexed to DNA reveals that the substrate is in the left-handed Z conformation. The contacts between Zalpha and Z-DNA are made primarily with the "zigzag" sugar-phosphate backbone, which provides a basis for the specificity for the Z conformation. A single base contact is observed to guanine in the syn conformation, characteristic of Z-DNA. Intriguingly, the helix-turn-helix motif, frequently used to recognize B-DNA, is used by Zalpha to contact Z-DNA.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Schwartz, T -- Rould, M A -- Lowenhaupt, K -- Herbert, A -- Rich, A -- New York, N.Y. -- Science. 1999 Jun 11;284(5421):1841-5.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/10364558" target="_blank"〉PubMed〈/a〉
    Keywords: Adenosine Deaminase/*chemistry/metabolism ; Amino Acid Sequence ; Binding Sites ; Crystallography, X-Ray ; DNA/chemistry/*metabolism ; Helix-Turn-Helix Motifs ; Humans ; Hydrogen Bonding ; Models, Molecular ; Molecular Sequence Data ; Nucleic Acid Conformation ; Protein Conformation ; Protein Structure, Secondary ; RNA-Binding Proteins ; Substrate Specificity ; Water/metabolism
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  • 29
    Publication Date: 1999-12-22
    Description: Ribosome recycling factor (RRF), together with elongation factor G (EF-G), catalyzes recycling of ribosomes after one round of protein synthesis. The crystal structure of RRF was determined at 2.55 angstrom resolution. The protein has an unusual fold where domain I is a long three-helix bundle and domain II is a three-layer beta/alpha/beta sandwich. The molecule superimposes almost perfectly with a transfer RNA (tRNA) except that the amino acid-binding 3' end is missing. The mimicry suggests that RRF interacts with the posttermination ribosomal complex in a similar manner to a tRNA, leading to disassembly of the complex. The structural arrangement of this mimicry is entirely different from that of other cases of less pronounced mimicry of tRNA so far described.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Selmer, M -- Al-Karadaghi, S -- Hirokawa, G -- Kaji, A -- Liljas, A -- New York, N.Y. -- Science. 1999 Dec 17;286(5448):2349-52.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Molecular Biophysics, Center for Chemistry and Chemical Engineering, Lund University, Post Office Box 124, SE-22100 Lund, Sweden.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/10600747" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acid Sequence ; Binding Sites ; Crystallography, X-Ray ; Models, Molecular ; *Molecular Mimicry ; Molecular Sequence Data ; Nucleic Acid Conformation ; Peptide Elongation Factor G/chemistry ; Protein Biosynthesis ; Protein Conformation ; Protein Folding ; Protein Structure, Secondary ; Protein Structure, Tertiary ; Proteins/*chemistry/*metabolism ; RNA, Bacterial/chemistry/metabolism ; RNA, Fungal/chemistry/metabolism ; RNA, Transfer/*chemistry/metabolism ; RNA, Transfer, Phe/chemistry/metabolism ; Ribosomal Proteins ; Ribosomes/*metabolism ; Sequence Alignment ; Thermotoga maritima/*chemistry/metabolism
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  • 30
    Publication Date: 1999-07-03
    Description: Regulation of N-methyl-D-aspartate (NMDA) receptor activity by kinases and phosphatases contributes to the modulation of synaptic transmission. Targeting of these enzymes near the substrate is proposed to enhance phosphorylation-dependent modulation. Yotiao, an NMDA receptor-associated protein, bound the type I protein phosphatase (PP1) and the adenosine 3',5'-monophosphate (cAMP)-dependent protein kinase (PKA) holoenzyme. Anchored PP1 was active, limiting channel activity, whereas PKA activation overcame constitutive PP1 activity and conferred rapid enhancement of NMDA receptor currents. Hence, yotiao is a scaffold protein that physically attaches PP1 and PKA to NMDA receptors to regulate channel activity.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Westphal, R S -- Tavalin, S J -- Lin, J W -- Alto, N M -- Fraser, I D -- Langeberg, L K -- Sheng, M -- Scott, J D -- F32 NS010202/NS/NINDS NIH HHS/ -- GM 48231/GM/NIGMS NIH HHS/ -- NS10202/NS/NINDS NIH HHS/ -- NS10543/NS/NINDS NIH HHS/ -- etc. -- New York, N.Y. -- Science. 1999 Jul 2;285(5424):93-6.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Howard Hughes Medical Institute, Vollum Institute, Oregon Health Sciences University, 3181 S.W. Sam Jackson Road, Portland, OR 97201, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/10390370" target="_blank"〉PubMed〈/a〉
    Keywords: A Kinase Anchor Proteins ; *Adaptor Proteins, Signal Transducing ; Amino Acid Sequence ; Animals ; Binding Sites ; Carrier Proteins/*metabolism ; Cell Line ; Cyclic AMP/analogs & derivatives/pharmacology ; Cyclic AMP-Dependent Protein Kinases/*metabolism ; Cytoskeletal Proteins/*metabolism ; Enzyme Inhibitors/pharmacology ; Holoenzymes/metabolism ; Humans ; Molecular Sequence Data ; Okadaic Acid/pharmacology ; Patch-Clamp Techniques ; Peptide Fragments/pharmacology ; Phosphoprotein Phosphatases/*metabolism ; Phosphorylation ; Rats ; Receptors, N-Methyl-D-Aspartate/*metabolism ; Recombinant Fusion Proteins/metabolism ; Signal Transduction ; Thionucleotides/pharmacology ; Transfection
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  • 31
    Publication Date: 1999-12-11
    Description: The multisubunit transcription factor IID (TFIID) is an essential component of the eukaryotic RNA polymerase II machinery that works in concert with TFIIA (IIA) and TFIIB (IIB) to assemble initiation complexes at core eukaryotic promoters. Here the structures of human TFIID and the TFIID-IIA-IIB complex that were obtained by electron microscopy and image analysis to 35 angstrom resolution are presented. TFIID is a trilobed, horseshoe-shaped structure, with TFIIA and TFIIB bound on opposite lobes and flanking a central cavity. Antibody studies locate the TATA-binding protein (TBP) between TFIIA and TFIIB at the top of the cavity that most likely encompasses the TATA DNA binding region of the supramolecular complex.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Andel, F 3rd -- Ladurner, A G -- Inouye, C -- Tjian, R -- Nogales, E -- New York, N.Y. -- Science. 1999 Dec 10;286(5447):2153-6.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Life Science Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/10591646" target="_blank"〉PubMed〈/a〉
    Keywords: Binding Sites ; DNA/metabolism ; DNA-Binding Proteins/chemistry/metabolism ; HeLa Cells ; Humans ; Image Processing, Computer-Assisted ; Microscopy, Electron ; Promoter Regions, Genetic ; Protein Conformation ; Recombinant Proteins/chemistry/metabolism ; TATA-Box Binding Protein ; Transcription Factor TFIIA ; Transcription Factor TFIIB ; Transcription Factor TFIID ; Transcription Factors/*chemistry/metabolism ; Transcription Factors, TFII/*chemistry/metabolism ; Transcription, Genetic
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  • 32
    Publication Date: 1999-03-05
    Description: Ribonucleotide reductases catalyze the reduction of ribonucleotides to deoxyribonucleotides. Three classes have been identified, all using free-radical chemistry but based on different cofactors. Classes I and II have been shown to be evolutionarily related, whereas the origin of anaerobic class III has remained elusive. The structure of a class III enzyme suggests a common origin for the three classes but shows differences in the active site that can be understood on the basis of the radical-initiation system and source of reductive electrons, as well as a unique protein glycyl radical site. A possible evolutionary relationship between early deoxyribonucleotide metabolism and primary anaerobic metabolism is suggested.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Logan, D T -- Andersson, J -- Sjoberg, B M -- Nordlund, P -- New York, N.Y. -- Science. 1999 Mar 5;283(5407):1499-504.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Biochemistry and Department of Molecular Biology, Stockholm University, S-106 91 Stockholm, Sweden. derek@biokemi.su.se〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/10066165" target="_blank"〉PubMed〈/a〉
    Keywords: Acetyltransferases/chemistry/metabolism ; Amino Acid Sequence ; Anaerobiosis ; Binding Sites ; Crystallography, X-Ray ; Dimerization ; Evolution, Molecular ; Glycine/*chemistry ; Hydrogen Bonding ; Models, Molecular ; Molecular Sequence Data ; Mutation ; Protein Conformation ; Protein Folding ; Protein Structure, Secondary ; Ribonucleotide Reductases/*chemistry/genetics/metabolism ; Viral Proteins/chemistry
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  • 33
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1999-07-03
    Description: The intramembrane molecular events underlying activation gating in the Streptomyces K+ channel were investigated by site-directed spin-labeling methods and electron paramagnetic resonance spectroscopy. A comparison of the closed and open conformations of the channel revealed periodic changes in spin-label mobility and intersubunit spin-spin interaction consistent with rigid-body movements of the two transmembrane helices TM1 and TM2. These changes involve translations and counterclockwise rotations of both helices relative to the center of symmetry of the channel. The movement of TM2 increases the diameter of the permeation pathway along the point of convergence of the four subunits, thus opening the pore. Although the extracellular residues flanking the selectivity filter remained immobile during gating, small movements were detected at the C-terminal end of the pore helix, with possible implications to the gating mechanism.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Perozo, E -- Cortes, D M -- Cuello, L G -- GM54690/GM/NIGMS NIH HHS/ -- GM57846/GM/NIGMS NIH HHS/ -- New York, N.Y. -- Science. 1999 Jul 2;285(5424):73-8.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Molecular Physiology and Biological Physics and Center for Structural Biology, University of Virginia Health Sciences Center, Charlottesville, VA 22906-0011, USA. eperozo@virginia.edu〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/10390363" target="_blank"〉PubMed〈/a〉
    Keywords: *Bacterial Proteins ; Binding Sites ; Circular Dichroism ; Cysteine/chemistry ; Electron Spin Resonance Spectroscopy ; Hydrogen-Ion Concentration ; *Ion Channel Gating ; Models, Molecular ; Potassium/*metabolism ; Potassium Channels/*chemistry/*physiology ; Protein Conformation ; Protein Structure, Secondary ; Rubidium/metabolism ; Sequence Deletion ; Streptomyces/chemistry/physiology
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  • 34
    Publication Date: 1999-04-30
    Description: The PDZ protein interaction domain of neuronal nitric oxide synthase (nNOS) can heterodimerize with the PDZ domains of postsynaptic density protein 95 and syntrophin through interactions that are not mediated by recognition of a typical carboxyl-terminal motif. The nNOS-syntrophin PDZ complex structure revealed that the domains interact in an unusual linear head-to-tail arrangement. The nNOS PDZ domain has two opposite interaction surfaces-one face has the canonical peptide binding groove, whereas the other has a beta-hairpin "finger." This nNOS beta finger docks in the syntrophin peptide binding groove, mimicking a peptide ligand, except that a sharp beta turn replaces the normally required carboxyl terminus. This structure explains how PDZ domains can participate in diverse interaction modes to assemble protein networks.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Hillier, B J -- Christopherson, K S -- Prehoda, K E -- Bredt, D S -- Lim, W A -- New York, N.Y. -- Science. 1999 Apr 30;284(5415):812-5.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Cellular and Molecular Pharmacology, University of California, San Francisco, San Francisco, CA 94143, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/10221915" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acid Sequence ; Binding Sites ; Crystallography, X-Ray ; Dimerization ; *Dystrophin-Associated Proteins ; Ligands ; Membrane Proteins/*chemistry/metabolism ; Molecular Sequence Data ; Muscle Proteins/*chemistry/metabolism ; Nitric Oxide Synthase/*chemistry/metabolism ; Nitric Oxide Synthase Type I ; Protein Conformation ; Protein Folding ; Protein Structure, Secondary ; Signal Transduction
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  • 35
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1999-09-11
    Description: Translational fidelity is established by ribosomal recognition of the codon-anticodon interaction within the aminoacyl-transfer RNA (tRNA) site (A site) of the ribosome. Experiments are presented that reveal possible contacts between 16S ribosomal RNA and the codon-anticodon complex. N1 methylation of adenine at position 1492 (A1492) and A1493 interfered with A-site tRNA binding. Mutation of A1492 and A1493 to guanine or cytosine also impaired A-site tRNA binding. The deleterious effects of A1492G or A1493G (or both) mutations were compensated by 2'fluorine substitutions in the mRNA codon. The results suggest that the ribosome recognizes the codon-anticodon complex by adenine contacts to the messenger RNA backbone and provide a mechanism for molecular discrimination of correct versus incorrect codon-anticodon pairs.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Yoshizawa, S -- Fourmy, D -- Puglisi, J D -- GM51266/GM/NIGMS NIH HHS/ -- New York, N.Y. -- Science. 1999 Sep 10;285(5434):1722-5.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Structural Biology, Stanford University School of Medicine, Stanford, CA 94305-5126, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/10481006" target="_blank"〉PubMed〈/a〉
    Keywords: Adenine/analogs & derivatives/metabolism ; Anticodon/chemistry/*metabolism ; Binding Sites ; Biotin ; Codon/chemistry/*metabolism ; Escherichia coli ; Hydrogen Bonding ; Methylation ; Mutagenesis, Site-Directed ; *Nucleic Acid Conformation ; Paromomycin/pharmacology ; Protein Biosynthesis ; RNA, Bacterial/chemistry/metabolism ; RNA, Ribosomal, 16S/chemistry/genetics/*metabolism ; RNA, Transfer, Met/metabolism ; RNA, Transfer, Phe/metabolism ; Ribosomes/*metabolism
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  • 36
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    Unknown
    American Association for the Advancement of Science (AAAS)
    Publication Date: 1999-02-05
    Description: The sterile alpha motif (SAM) domain is a protein interaction module that is present in diverse signal-transducing proteins. SAM domains are known to form homo- and hetero-oligomers. The crystal structure of the SAM domain from an Eph receptor tyrosine kinase, EphB2, reveals two large interfaces. In one interface, adjacent monomers exchange amino-terminal peptides that insert into a hydrophobic groove on each neighbor. A second interface is composed of the carboxyl-terminal helix and a nearby loop. A possible oligomer, constructed from a combination of these binding modes, may provide a platform for the formation of larger protein complexes.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Thanos, C D -- Goodwill, K E -- Bowie, J U -- New York, N.Y. -- Science. 1999 Feb 5;283(5403):833-6.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉UCLA-DOE Laboratory of Structural Biology and Molecular Medicine and Department of Chemistry and Biochemistry, University of California, Los Angeles, CA 90095, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/9933164" target="_blank"〉PubMed〈/a〉
    Keywords: Binding Sites ; Crystallization ; Crystallography, X-Ray ; Dimerization ; GRB10 Adaptor Protein ; Humans ; Hydrogen Bonding ; Kinesin/metabolism ; Models, Molecular ; Myosins/metabolism ; Phosphorylation ; *Protein Conformation ; Protein Structure, Secondary ; Protein Tyrosine Phosphatases/metabolism ; Proteins/metabolism ; Receptor Aggregation ; Receptor Protein-Tyrosine Kinases/*chemistry/metabolism ; Receptor, EphB2 ; Recombinant Proteins/chemistry/metabolism ; Surface Properties
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  • 37
    Publication Date: 1999-06-26
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉McLafferty, F W -- Fridriksson, E K -- Horn, D M -- Lewis, M A -- Zubarev, R A -- New York, N.Y. -- Science. 1999 May 21;284(5418):1289-90.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY 14853-1301, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/10383309" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acid Sequence ; Binding Sites ; DNA/*chemistry/isolation & purification/metabolism ; Mass Spectrometry/instrumentation/*methods ; Molecular Sequence Data ; Molecular Weight ; Proteins/*chemistry/isolation & purification/metabolism ; Sequence Analysis ; Sequence Analysis, DNA ; Thermodynamics ; Ubiquitins/chemistry
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  • 38
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1999-07-27
    Description: The patterned expression of floral homeotic genes in Arabidopsis depends on the earlier action of meristem-identity genes such as LEAFY, which encodes a transcription factor that determines whether a meristem will generate flowers instead of leaves and shoots. The LEAFY protein, which is expressed throughout the flower, participates in the activation of homeotic genes, which are expressed in specific regions of the flower. Analysis of a LEAFY-responsive enhancer in the homeotic gene AGAMOUS indicates that direct interaction of LEAFY with this enhancer is required for its activity in plants. Thus, LEAFY is a direct upstream regulator of floral homeotic genes.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Busch, M A -- Bomblies, K -- Weigel, D -- New York, N.Y. -- Science. 1999 Jul 23;285(5427):585-7.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉The Salk Institute for Biological Studies, 10010 North Torrey Pines Road, La Jolla, CA 92037, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/10417388" target="_blank"〉PubMed〈/a〉
    Keywords: AGAMOUS Protein, Arabidopsis ; Arabidopsis/*genetics ; *Arabidopsis Proteins ; Binding Sites ; DNA-Binding Proteins/*genetics ; Enhancer Elements, Genetic ; *Gene Expression Regulation, Plant ; *Genes, Homeobox ; Genes, Plant ; Genes, Reporter ; Meristem/genetics/metabolism ; Plant Proteins/*genetics/*metabolism ; Plant Structures/genetics/metabolism ; Point Mutation ; Trans-Activators/genetics/metabolism ; *Transcription Factors ; *Transcriptional Activation
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  • 39
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    Unknown
    American Association for the Advancement of Science (AAAS)
    Publication Date: 1999-12-03
    Description: Eighteen codons in the HA1 domain of the hemagglutinin genes of human influenza A subtype H3 appear to be under positive selection to change the amino acid they encode. Retrospective tests show that viral lineages undergoing the greatest number of mutations in the positively selected codons were the progenitors of future H3 lineages in 9 of 11 recent influenza seasons. Codons under positive selection were associated with antibody combining site A or B or the sialic acid receptor binding site. However, not all codons in these sites had predictive value. Monitoring new H3 isolates for additional changes in positively selected codons might help identify the most fit extant viral strains that arise during antigenic drift.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Bush, R M -- Bender, C A -- Subbarao, K -- Cox, N J -- Fitch, W M -- New York, N.Y. -- Science. 1999 Dec 3;286(5446):1921-5.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Ecology and Evolutionary Biology, University of California, Irvine, CA 92697, USA. rmbush@uci.edu〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/10583948" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acid Substitution ; *Antigenic Variation ; Binding Sites ; Codon ; Epitopes ; *Evolution, Molecular ; Forecasting ; Genes, Viral ; Hemagglutinin Glycoproteins, Influenza Virus/chemistry/*genetics/immunology ; Humans ; Influenza A virus/*genetics/immunology ; Influenza, Human/*virology ; Mutation ; *Phylogeny ; Probability ; Protein Structure, Tertiary ; Receptors, Cell Surface/metabolism ; Retrospective Studies ; Selection, Genetic
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  • 40
    Publication Date: 1999-10-26
    Description: Cerebral deposition of amyloid beta peptide (Abeta) is an early and critical feature of Alzheimer's disease. Abeta generation depends on proteolytic cleavage of the amyloid precursor protein (APP) by two unknown proteases: beta-secretase and gamma-secretase. These proteases are prime therapeutic targets. A transmembrane aspartic protease with all the known characteristics of beta-secretase was cloned and characterized. Overexpression of this protease, termed BACE (for beta-site APP-cleaving enzyme) increased the amount of beta-secretase cleavage products, and these were cleaved exactly and only at known beta-secretase positions. Antisense inhibition of endogenous BACE messenger RNA decreased the amount of beta-secretase cleavage products, and purified BACE protein cleaved APP-derived substrates with the same sequence specificity as beta-secretase. Finally, the expression pattern and subcellular localization of BACE were consistent with that expected for beta-secretase. Future development of BACE inhibitors may prove beneficial for the treatment of Alzheimer's disease.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Vassar, R -- Bennett, B D -- Babu-Khan, S -- Kahn, S -- Mendiaz, E A -- Denis, P -- Teplow, D B -- Ross, S -- Amarante, P -- Loeloff, R -- Luo, Y -- Fisher, S -- Fuller, J -- Edenson, S -- Lile, J -- Jarosinski, M A -- Biere, A L -- Curran, E -- Burgess, T -- Louis, J C -- Collins, F -- Treanor, J -- Rogers, G -- Citron, M -- New York, N.Y. -- Science. 1999 Oct 22;286(5440):735-41.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Amgen, Inc., One Amgen Center Drive, M/S 29-2-B, Thousand Oaks, CA 91320-1799, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/10531052" target="_blank"〉PubMed〈/a〉
    Keywords: Alzheimer Disease/drug therapy/*enzymology ; Amino Acid Motifs ; Amino Acid Sequence ; Amyloid Precursor Protein Secretases ; Amyloid beta-Peptides/*biosynthesis ; Amyloid beta-Protein Precursor/*metabolism ; Animals ; Aspartic Acid Endopeptidases/chemistry/genetics/*isolation & ; purification/*metabolism ; Binding Sites ; Brain/enzymology/metabolism ; Cell Line ; Cloning, Molecular ; Endopeptidases ; Endosomes/enzymology ; Gene Expression ; Gene Library ; Golgi Apparatus/enzymology ; Humans ; Hydrogen-Ion Concentration ; Molecular Sequence Data ; Oligonucleotides, Antisense/pharmacology ; Peptides/metabolism ; Protease Inhibitors/pharmacology ; RNA, Messenger/genetics/metabolism ; Recombinant Fusion Proteins/metabolism ; Transfection
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  • 41
    Publication Date: 1999-05-21
    Description: Polyketides, the ubiquitous products of secondary metabolism in microorganisms, are made by a process resembling fatty acid biosynthesis that allows the suppression of reduction or dehydration reactions at specific biosynthetic steps, giving rise to a wide range of often medically useful products. The lovastatin biosynthesis cluster contains two type I polyketide synthase genes. Synthesis of the main nonaketide-derived skeleton was found to require the previously known iterative lovastatin nonaketide synthase (LNKS), plus at least one additional protein (LovC) that interacts with LNKS and is necessary for the correct processing of the growing polyketide chain and production of dihydromonacolin L. The noniterative lovastatin diketide synthase (LDKS) enzyme specifies formation of 2-methylbutyrate and interacts closely with an additional transesterase (LovD) responsible for assembling lovastatin from this polyketide and monacolin J.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Kennedy, J -- Auclair, K -- Kendrew, S G -- Park, C -- Vederas, J C -- Hutchinson, C R -- AI43031/AI/NIAID NIH HHS/ -- New York, N.Y. -- Science. 1999 May 21;284(5418):1368-72.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉School of Pharmacy, Bacteriology Department, University of Wisconsin, Madison, WI 53706, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/10334994" target="_blank"〉PubMed〈/a〉
    Keywords: Aspergillus/enzymology/genetics/*metabolism ; Aspergillus nidulans/enzymology/genetics/metabolism ; Binding Sites ; Butyrates/metabolism ; Esterases/*metabolism ; Fungal Proteins/*metabolism ; Genes, Fungal ; Lovastatin/*biosynthesis ; Multienzyme Complexes/chemistry/genetics/*metabolism ; Naphthalenes/metabolism
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  • 42
    Publication Date: 1999-09-25
    Description: Structures of 70S ribosome complexes containing messenger RNA and transfer RNA (tRNA), or tRNA analogs, have been solved by x-ray crystallography at up to 7.8 angstrom resolution. Many details of the interactions between tRNA and the ribosome, and of the packing arrangements of ribosomal RNA (rRNA) helices in and between the ribosomal subunits, can be seen. Numerous contacts are made between the 30S subunit and the P-tRNA anticodon stem-loop; in contrast, the anticodon region of A-tRNA is much more exposed. A complex network of molecular interactions suggestive of a functional relay is centered around the long penultimate stem of 16S rRNA at the subunit interface, including interactions involving the "switch" helix and decoding site of 16S rRNA, and RNA bridges from the 50S subunit.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Cate, J H -- Yusupov, M M -- Yusupova, G Z -- Earnest, T N -- Noller, H F -- GM-17129/GM/NIGMS NIH HHS/ -- GM-59140/GM/NIGMS NIH HHS/ -- New York, N.Y. -- Science. 1999 Sep 24;285(5436):2095-104.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Center for Molecular Biology of RNA, Sinsheimer Laboratories, University of California, Santa Cruz, CA 95064, USA. cate@wi.mit.edu〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/10497122" target="_blank"〉PubMed〈/a〉
    Keywords: Anticodon/metabolism ; Bacterial Proteins/chemistry/metabolism ; Base Pairing ; Binding Sites ; Crystallization ; Crystallography, X-Ray ; Fourier Analysis ; Models, Molecular ; Nucleic Acid Conformation ; Peptide Elongation Factors/metabolism ; Protein Biosynthesis ; Protein Conformation ; RNA, Bacterial/chemistry/metabolism ; RNA, Messenger/chemistry/metabolism ; RNA, Ribosomal/*chemistry/metabolism ; RNA, Ribosomal, 16S/chemistry ; RNA, Ribosomal, 23S/chemistry ; RNA, Transfer/*chemistry/metabolism ; Ribosomal Proteins/chemistry/metabolism ; Ribosomes/*chemistry/*physiology/ultrastructure ; Thermus thermophilus/*chemistry/ultrastructure
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  • 43
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1999-04-17
    Description: Zn-alpha2-glycoprotein (ZAG) is a soluble protein that is present in serum and other body fluids. ZAG stimulates lipid degradation in adipocytes and causes the extensive fat losses associated with some advanced cancers. The 2.8 angstrom crystal structure of ZAG resembles a class I major histocompatibility complex (MHC) heavy chain, but ZAG does not bind the class I light chain beta2-microglobulin. The ZAG structure includes a large groove analogous to class I MHC peptide binding grooves. Instead of a peptide, the ZAG groove contains a nonpeptidic compound that may be implicated in lipid catabolism under normal or pathological conditions.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Sanchez, L M -- Chirino, A J -- Bjorkman, P j -- New York, N.Y. -- Science. 1999 Mar 19;283(5409):1914-9.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Division of Biology, California Institute of Technology, Pasadena, CA 91125, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/10206894" target="_blank"〉PubMed〈/a〉
    Keywords: Binding Sites ; Crystallography, X-Ray ; Glycoproteins/blood/*chemistry/isolation & purification/metabolism ; Glycosylation ; HLA-A2 Antigen/chemistry/metabolism ; Histocompatibility Antigens Class I/*chemistry ; Humans ; Hydrogen Bonding ; Ligands ; Lipid Metabolism ; Models, Molecular ; Peptides/metabolism ; Protein Binding ; Protein Conformation ; Protein Folding ; Protein Structure, Secondary ; Protein Structure, Tertiary ; *Seminal Plasma Proteins ; beta 2-Microglobulin/metabolism
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  • 44
    Publication Date: 1999-09-08
    Description: Targeting of protein modification enzymes is a key biochemical step to achieve specific and effective posttranslational modifications. Two alternatively spliced ZIP1 and ZIP2 proteins are described, which bind to both Kvbeta2 subunits of potassium channel and protein kinase C (PKC) zeta, thereby acting as a physical link in the assembly of PKCzeta-ZIP-potassium channel complexes. ZIP1 and ZIP2 differentially stimulate phosphorylation of Kvbeta2 by PKCzeta. They also interact to form heteromultimers, which allows for a hybrid stimulatory activity to PKCzeta. Finally, ZIP1 and ZIP2 coexist in the same cell type and are elevated differentially by neurotrophic factors. These results provide a mechanism for specificity and regulation of PKCzeta-targeted phosphorylation.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Gong, J -- Xu, J -- Bezanilla, M -- van Huizen, R -- Derin, R -- Li, M -- NS33324/NS/NINDS NIH HHS/ -- New York, N.Y. -- Science. 1999 Sep 3;285(5433):1565-9.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Physiology, The Johns Hopkins University School of Medicine, 725 North Wolfe Street, Baltimore, MD 21205, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/10477520" target="_blank"〉PubMed〈/a〉
    Keywords: Alternative Splicing ; Amino Acid Sequence ; Animals ; Binding Sites ; Carrier Proteins/chemistry/genetics/*metabolism ; Cell Line ; Cerebellum/metabolism ; DNA, Complementary ; Isoenzymes/metabolism ; Molecular Sequence Data ; Myelin Basic Protein/metabolism ; Nerve Growth Factors/pharmacology ; Neurons/*metabolism ; Phosphorylation ; Potassium Channels/*metabolism ; Protein Kinase C/*metabolism ; Pyramidal Cells/metabolism ; RNA, Messenger/genetics/metabolism ; Rats ; Rats, Sprague-Dawley ; Recombinant Fusion Proteins/chemistry/metabolism ; Substrate Specificity ; Transfection
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  • 45
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1999-12-28
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Nebreda, A R -- Gavin, A C -- New York, N.Y. -- Science. 1999 Nov 12;286(5443):1309-10.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉European Molecular Biology Laboratory, Heidelberg, Germany. nebreda@embl-heidelberg.de〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/10610536" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Binding Sites ; *Cell Cycle ; *Cell Survival ; Cerebellum/cytology ; Enzyme Activation ; Humans ; *MAP Kinase Signaling System ; Meiosis ; Metaphase ; Mitogen-Activated Protein Kinases/metabolism ; Neurons/cytology ; Phosphorylation ; Ribosomal Protein S6 Kinases/chemistry/*metabolism ; Signal Transduction ; Transcriptional Activation
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  • 46
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    Unknown
    American Association for the Advancement of Science (AAAS)
    Publication Date: 1999-10-16
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Hagmann, M -- New York, N.Y. -- Science. 1999 Sep 24;285(5436):2042.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/10523192" target="_blank"〉PubMed〈/a〉
    Keywords: Binding Sites ; Calcineurin/metabolism ; *Calcineurin Inhibitors ; Cells, Cultured ; DNA-Binding Proteins/*antagonists & inhibitors/metabolism ; Gene Expression Regulation ; Humans ; Immunosuppressive Agents/chemistry/metabolism/*pharmacology ; NFATC Transcription Factors ; *Nuclear Proteins ; Peptide Library ; Peptides/chemistry/metabolism/*pharmacology ; T-Lymphocytes/*drug effects/immunology ; Transcription Factors/*antagonists & inhibitors/metabolism
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  • 47
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    Unknown
    American Association for the Advancement of Science (AAAS)
    Publication Date: 1999-05-15
    Description: The structure of a highly conserved complex between a 58-nucleotide domain of large subunit ribosomal RNA and the RNA-binding domain of ribosomal protein L11 has been solved at 2.8 angstrom resolution. It reveals a precisely folded RNA structure that is stabilized by extensive tertiary contacts and contains an unusually large core of stacked bases. A bulge loop base from one hairpin of the RNA is intercalated into the distorted major groove of another helix; the protein locks this tertiary interaction into place by binding to the intercalated base from the minor groove side. This direct interaction with a key ribosomal RNA tertiary interaction suggests that part of the role of L11 is to stabilize an unusual RNA fold within the ribosome.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Conn, G L -- Draper, D E -- Lattman, E E -- Gittis, A G -- R37 GM29048/GM/NIGMS NIH HHS/ -- New York, N.Y. -- Science. 1999 May 14;284(5417):1171-4.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Chemistry, Johns Hopkins University, Baltimore, MD 21218, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/10325228" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acid Sequence ; Bacterial Proteins/chemistry/metabolism ; Base Pairing ; Base Sequence ; Binding Sites ; Crystallography, X-Ray ; Hydrogen Bonding ; Models, Molecular ; Molecular Sequence Data ; *Nucleic Acid Conformation ; Peptide Elongation Factor G ; Peptide Elongation Factors/metabolism ; Phylogeny ; Protein Conformation ; RNA, Bacterial/*chemistry/metabolism ; RNA, Ribosomal/*chemistry/metabolism ; Ribosomal Proteins/*chemistry/metabolism
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  • 48
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1999-06-26
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Hagmann, M -- New York, N.Y. -- Science. 1999 Jun 4;284(5420):1600-1.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/10383332" target="_blank"〉PubMed〈/a〉
    Keywords: ADAM Proteins ; Animals ; Antineoplastic Agents ; Antirheumatic Agents ; Arthritis/*drug therapy ; Binding Sites ; Cloning, Molecular ; Enzyme Precursors/chemistry/metabolism ; Gelatinases/antagonists & inhibitors/*chemistry/metabolism ; Humans ; Matrix Metalloproteinase 2 ; Metalloendopeptidases/antagonists & inhibitors/*chemistry/genetics/metabolism ; Mice ; Models, Molecular ; Neoplasms/*drug therapy ; Procollagen N-Endopeptidase ; Protease Inhibitors/*pharmacology ; Protein Conformation ; Protein Structure, Secondary
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  • 49
    Publication Date: 1999-07-31
    Description: Estrogen receptor alpha transcriptional activity is regulated by distinct conformational states that are the result of ligand binding. Phage display was used to identify peptides that interact specifically with either estradiol- or tamoxifen-activated estrogen receptor alpha. When these peptides were coexpressed with estrogen receptor alpha in cells, they functioned as ligand-specific antagonists, indicating that estradiol-agonist and tamoxifen-partial agonist activities do not occur by the same mechanism. The ability to regulate estrogen receptor alpha transcriptional activity by targeting sites outside of the ligand-binding pocket has implications for the development of estrogen receptor alpha antagonists for the treatment of tamoxifen-refractory breast cancers.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Norris, J D -- Paige, L A -- Christensen, D J -- Chang, C Y -- Huacani, M R -- Fan, D -- Hamilton, P T -- Fowlkes, D M -- McDonnell, D P -- DK48807/DK/NIDDK NIH HHS/ -- New York, N.Y. -- Science. 1999 Jul 30;285(5428):744-6.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Duke University Medical Center, Department of Pharmacology and Cancer Biology, Durham, NC 27710, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/10426998" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acid Sequence ; Binding Sites ; Estradiol/metabolism/*pharmacology ; Estrogen Antagonists/*pharmacology ; Estrogen Receptor alpha ; Humans ; Ligands ; Mifepristone/pharmacology ; Molecular Sequence Data ; Peptide Library ; Peptides/metabolism/*pharmacology ; Receptors, Cytoplasmic and Nuclear/metabolism ; Receptors, Estrogen/agonists/*antagonists & inhibitors/chemistry/*metabolism ; Recombinant Fusion Proteins/pharmacology ; Tamoxifen/metabolism/*pharmacology ; Transcription Factor AP-1/genetics/metabolism ; Transcription, Genetic/drug effects
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  • 50
    Publication Date: 1999-04-24
    Description: Only a few intracellular S-nitrosylated proteins have been identified, and it is unknown if protein S-nitrosylation/denitrosylation is a component of signal transduction cascades. Caspase-3 zymogens were found to be S-nitrosylated on their catalytic-site cysteine in unstimulated human cell lines and denitrosylated upon activation of the Fas apoptotic pathway. Decreased caspase-3 S-nitrosylation was associated with an increase in intracellular caspase activity. Fas therefore activates caspase-3 not only by inducing the cleavage of the caspase zymogen to its active subunits, but also by stimulating the denitrosylation of its active-site thiol. Protein S-nitrosylation/denitrosylation can thus serve as a regulatory process in signal transduction pathways.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Mannick, J B -- Hausladen, A -- Liu, L -- Hess, D T -- Zeng, M -- Miao, Q X -- Kane, L S -- Gow, A J -- Stamler, J S -- GM57601-01/GM/NIGMS NIH HHS/ -- HL52529/HL/NHLBI NIH HHS/ -- HL59130/HL/NHLBI NIH HHS/ -- New York, N.Y. -- Science. 1999 Apr 23;284(5414):651-4.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Adult Oncology, Dana Farber Cancer Institute, 44 Binney Street, Boston, MA 02115, USA. joan_mannick@dfci.harvard.edu〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/10213689" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Antigens, CD95/*physiology ; Apoptosis ; Binding Sites ; Caspase 3 ; Caspases/*metabolism ; Cell Line ; Cysteine/*metabolism ; Enzyme Activation ; Enzyme Inhibitors/pharmacology ; Enzyme Precursors/metabolism ; Humans ; *Mercaptoethanol ; Nitric Oxide/*metabolism ; Nitric Oxide Synthase/antagonists & inhibitors ; Nitrites/metabolism ; Nitroso Compounds/metabolism ; *S-Nitrosothiols ; Signal Transduction ; omega-N-Methylarginine/pharmacology
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  • 51
    Publication Date: 1999-07-31
    Description: A computational method is proposed for inferring protein interactions from genome sequences on the basis of the observation that some pairs of interacting proteins have homologs in another organism fused into a single protein chain. Searching sequences from many genomes revealed 6809 such putative protein-protein interactions in Escherichia coli and 45,502 in yeast. Many members of these pairs were confirmed as functionally related; computational filtering further enriches for interactions. Some proteins have links to several other proteins; these coupled links appear to represent functional interactions such as complexes or pathways. Experimentally confirmed interacting pairs are documented in a Database of Interacting Proteins.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Marcotte, E M -- Pellegrini, M -- Ng, H L -- Rice, D W -- Yeates, T O -- Eisenberg, D -- P01 GM 31299/GM/NIGMS NIH HHS/ -- New York, N.Y. -- Science. 1999 Jul 30;285(5428):751-3.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉UCLA-Department of Energy Laboratory of Structural Biology and Molecular Medicine, University of California at Los Angeles, Los Angeles, CA 90095-1570, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/10427000" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acid Sequence ; Bacterial Proteins/chemistry/genetics/metabolism/physiology ; Binding Sites ; *Computational Biology ; Databases, Factual ; Escherichia coli/genetics ; Evolution, Molecular ; Fungal Proteins/chemistry/genetics/metabolism ; *Genome ; Genome, Bacterial ; Genome, Fungal ; Humans ; Models, Biological ; Proteins/chemistry/genetics/metabolism/*physiology ; *Sequence Homology, Amino Acid ; *Sequence Homology, Nucleic Acid ; Thermodynamics
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  • 52
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1999-10-03
    Description: Cdc13 and Est1 are single-strand telomeric DNA binding proteins that contribute to telomere replication in the yeast Saccharomyces cerevisiae. Here it is shown that fusion of Cdc13 to the telomerase-associated Est1 protein results in greatly elongated telomeres. Fusion proteins consisting of mutant versions of Cdc13 or Est1 confer similar telomere elongation, indicating that close physical proximity can bypass telomerase-defective mutations in either protein. Fusing Cdc13 directly to the catalytic core of telomerase allows stable telomere maintenance in the absence of Est1, consistent with a role for Est1 in mediating telomerase access. Telomere length homeostasis therefore is maintained in part by restricting access of telomerase to chromosome termini, but this limiting situation can be overcome by directly tethering telomerase to the telomere.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Evans, S K -- Lundblad, V -- R01GM55867/GM/NIGMS NIH HHS/ -- New York, N.Y. -- Science. 1999 Oct 1;286(5437):117-20.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/10506558" target="_blank"〉PubMed〈/a〉
    Keywords: Binding Sites ; Cyclin B/genetics/*metabolism ; DNA, Fungal/metabolism ; DNA, Single-Stranded/metabolism ; Fungal Proteins/genetics/*metabolism ; Genetic Complementation Test ; Homeostasis ; Models, Biological ; Mutation ; Recombinant Fusion Proteins/metabolism ; Saccharomyces cerevisiae/genetics/growth & development/*metabolism ; *Saccharomyces cerevisiae Proteins ; Telomerase/genetics/*metabolism ; Telomere/*metabolism
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  • 53
    Publication Date: 1999-06-18
    Description: The integral membrane protein fumarate reductase catalyzes the final step of anaerobic respiration when fumarate is the terminal electron acceptor. The homologous enzyme succinate dehydrogenase also plays a prominent role in cellular energetics as a member of the Krebs cycle and as complex II of the aerobic respiratory chain. Fumarate reductase consists of four subunits that contain a covalently linked flavin adenine dinucleotide, three different iron-sulfur clusters, and at least two quinones. The crystal structure of intact fumarate reductase has been solved at 3.3 angstrom resolution and demonstrates that the cofactors are arranged in a nearly linear manner from the membrane-bound quinone to the active site flavin. Although fumarate reductase is not associated with any proton-pumping function, the two quinones are positioned on opposite sides of the membrane in an arrangement similar to that of the Q-cycle organization observed for cytochrome bc1.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Iverson, T M -- Luna-Chavez, C -- Cecchini, G -- Rees, D C -- New York, N.Y. -- Science. 1999 Jun 18;284(5422):1961-6.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Graduate Option in Biochemistry, 147-75CH, California Institute of Technology, Pasadena, CA 91125, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/10373108" target="_blank"〉PubMed〈/a〉
    Keywords: Aerobiosis ; Anaerobiosis ; Binding Sites ; Cell Membrane/enzymology ; Crystallization ; Crystallography, X-Ray ; Electron Transport ; Energy Metabolism ; Escherichia coli/*enzymology ; Flavin-Adenine Dinucleotide/metabolism ; Fumarates/metabolism ; Iron-Sulfur Proteins/chemistry/metabolism ; Models, Molecular ; Oxidation-Reduction ; Oxygen Consumption ; Protein Conformation ; Protein Folding ; Quinones/chemistry/metabolism ; Succinate Dehydrogenase/*chemistry/metabolism
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  • 54
    Publication Date: 1999-06-26
    Description: Motilin is a 22-amino acid peptide hormone expressed throughout the gastrointestinal (GI) tract of humans and other species. It affects gastric motility by stimulating interdigestive antrum and duodenal contractions. A heterotrimeric guanosine triphosphate-binding protein (G protein)-coupled receptor for motilin was isolated from human stomach, and its amino acid sequence was found to be 52 percent identical to the human receptor for growth hormone secretagogues. The macrolide antibiotic erythromycin also interacted with the cloned motilin receptor, providing a molecular basis for its effects on the human GI tract. The motilin receptor is expressed in enteric neurons of the human duodenum and colon. Development of motilin receptor agonists and antagonists may be useful in the treatment of multiple disorders of GI motility.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Feighner, S D -- Tan, C P -- McKee, K K -- Palyha, O C -- Hreniuk, D L -- Pong, S S -- Austin, C P -- Figueroa, D -- MacNeil, D -- Cascieri, M A -- Nargund, R -- Bakshi, R -- Abramovitz, M -- Stocco, R -- Kargman, S -- O'Neill, G -- Van Der Ploeg, L H -- Evans, J -- Patchett, A A -- Smith, R G -- Howard, A D -- New York, N.Y. -- Science. 1999 Jun 25;284(5423):2184-8.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Metabolic Disorders, Department of Medicinal Chemistry, Merck Research Laboratories, Building RY-80Y-265, 126 East Lincoln Avenue, Rahway, NJ 07065, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/10381885" target="_blank"〉PubMed〈/a〉
    Keywords: Alternative Splicing ; Amino Acid Sequence ; Base Sequence ; Binding Sites ; Calcium/metabolism ; Cell Line ; Chromosome Mapping ; Chromosomes, Human, Pair 13 ; Cloning, Molecular ; Colon/*metabolism ; Erythromycin/metabolism ; GTP-Binding Proteins/metabolism ; Humans ; In Situ Hybridization ; Intestine, Small/*metabolism ; Ligands ; Molecular Sequence Data ; Motilin/analogs & derivatives/*metabolism ; Receptors, Gastrointestinal Hormone/*chemistry/*genetics/metabolism ; Receptors, Neuropeptide/*chemistry/*genetics/metabolism ; Stomach/*metabolism ; Thyroid Gland/metabolism ; Transfection
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  • 55
    Publication Date: 1999-11-13
    Description: Transcriptional coactivators have been viewed as constitutively active components, using transcription factors mainly to localize their functions. Here, it is shown that PPARgamma coactivator-1 (PGC-1) promotes transcription through the assembly of a complex that includes the histone acetyltransferases steroid receptor coactivator-1 (SRC-1) and CREB binding protein (CBP)/p300. PGC-1 has a low inherent transcriptional activity when it is not bound to a transcription factor. The docking of PGC-1 to peroxisome proliferator-activated receptor gamma (PPARgamma) stimulates an apparent conformational change in PGC-1 that permits binding of SRC-1 and CBP/p300, resulting in a large increase in transcriptional activity. Thus, transcription factor docking switches on the activity of a coactivator protein.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Puigserver, P -- Adelmant, G -- Wu, Z -- Fan, M -- Xu, J -- O'Malley, B -- Spiegelman, B M -- DK54477/DK/NIDDK NIH HHS/ -- New York, N.Y. -- Science. 1999 Nov 12;286(5443):1368-71.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Dana-Farber Cancer Institute and Department of Cell Biology, Harvard Medical School, Boston, MA 02115, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/10558993" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Binding Sites ; COS Cells ; DNA-Binding Proteins/metabolism ; E1A-Associated p300 Protein ; Gene Expression Regulation ; Histone Acetyltransferases ; Mice ; Nuclear Proteins/chemistry/*metabolism ; Nuclear Receptor Coactivator 1 ; Nuclear Respiratory Factors ; Protein Binding ; Protein Conformation ; Receptors, Cytoplasmic and Nuclear/*metabolism ; Recombinant Fusion Proteins/metabolism ; Trans-Activators/chemistry/*metabolism ; Transcription Factors/chemistry/*metabolism ; *Transcription, Genetic ; Transfection
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  • 56
    Publication Date: 1999-08-14
    Description: The three-dimensional (3D) structure of the intrinsically dimeric insulin receptor bound to its ligand, insulin, was determined by electron cryomicroscopy. Gold-labeled insulin served to locate the insulin-binding domain. The 3D structure was then fitted with available known high-resolution domain substructures to obtain a detailed contiguous model for this heterotetrameric transmembrane receptor. The 3D reconstruction indicates that the two alpha subunits jointly participate in insulin binding and that the kinase domains in the two beta subunits are in a juxtaposition that permits autophosphorylation of tyrosine residues in the first step of insulin receptor activation.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Luo, R Z -- Beniac, D R -- Fernandes, A -- Yip, C C -- Ottensmeyer, F P -- New York, N.Y. -- Science. 1999 Aug 13;285(5430):1077-80.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Banting and Best Department of Medical Research, University of Toronto, Toronto, Ontario, M5G 1L6, Canada.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/10446056" target="_blank"〉PubMed〈/a〉
    Keywords: Binding Sites ; Catalytic Domain ; Crystallography, X-Ray ; Dimerization ; Gold ; Image Processing, Computer-Assisted ; Insulin/*chemistry/metabolism ; Ligands ; Microscopy, Electron, Scanning Transmission ; Models, Molecular ; Phosphorylation ; Protein Conformation ; Protein-Tyrosine Kinases/chemistry/metabolism ; Receptor, Insulin/*chemistry/metabolism
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  • 57
    Publication Date: 1999-12-03
    Description: The crystal structure of a complex involving the D10 T cell receptor (TCR), 16-residue foreign peptide antigen, and the I-Ak self major histocompatibility complex (MHC) class II molecule is reported at 3.2 angstrom resolution. The D10 TCR is oriented in an orthogonal mode relative to its peptide-MHC (pMHC) ligand, necessitated by the amino-terminal extension of peptide residues projecting from the MHC class II antigen-binding groove as part of a mini beta sheet. Consequently, the disposition of D10 complementarity-determining region loops is altered relative to that of most pMHCI-specific TCRs; the latter TCRs assume a diagonal orientation, although with substantial variability. Peptide recognition, which involves P-1 to P8 residues, is dominated by the Valpha domain, which also binds to the class II MHC beta1 helix. That docking is limited to one segment of MHC-bound peptide offers an explanation for epitope recognition and altered peptide ligand effects, suggests a structural basis for alloreactivity, and illustrates how bacterial superantigens can span the TCR-pMHCII surface.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Reinherz, E L -- Tan, K -- Tang, L -- Kern, P -- Liu, J -- Xiong, Y -- Hussey, R E -- Smolyar, A -- Hare, B -- Zhang, R -- Joachimiak, A -- Chang, H C -- Wagner, G -- Wang, J -- AI/CA37581/AI/NIAID NIH HHS/ -- AI19807/AI/NIAID NIH HHS/ -- GM56008/GM/NIGMS NIH HHS/ -- New York, N.Y. -- Science. 1999 Dec 3;286(5446):1913-21.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Laboratory of Immunobiology, Dana-Farber Cancer Institute, Department of Medicine, Harvard Medical School, Boston, MA 02115, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/10583947" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Antigens/*chemistry/immunology/metabolism ; Binding Sites ; CD4-Positive T-Lymphocytes/immunology ; CD8-Positive T-Lymphocytes/immunology ; Conalbumin/chemistry/immunology ; Crystallization ; Crystallography, X-Ray ; Histocompatibility Antigens Class I/immunology ; Histocompatibility Antigens Class II/*chemistry/immunology/metabolism ; Hydrogen Bonding ; Ligands ; Mice ; Mice, Inbred AKR ; Models, Molecular ; Oligopeptides/chemistry/immunology/metabolism ; Protein Conformation ; Protein Structure, Secondary ; Protein Structure, Tertiary ; Receptors, Antigen, T-Cell, alpha-beta/*chemistry/immunology/metabolism ; Superantigens/immunology/metabolism ; Thymus Gland/cytology/immunology
    Print ISSN: 0036-8075
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  • 58
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1999-04-16
    Description: The crystal structures of myoglobin in the deoxy- and carbon monoxide-ligated states at a resolution of 1.15 angstroms show that carbon monoxide binding at ambient temperatures requires concerted motions of the heme, the iron, and helices E and F for relief of steric inhibition. These steps constitute the main mechanism by which heme proteins lower the affinity of the heme group for the toxic ligand carbon monoxide.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Kachalova, G S -- Popov, A N -- Bartunik, H D -- New York, N.Y. -- Science. 1999 Apr 16;284(5413):473-6.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Max-Planck-Arbeitsgruppen fur Strukturelle Molekularbiologie, Arbeitsgruppe Proteindynamik, Notkestrabetae 85, 22603 Hamburg, Germany.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/10205052" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Binding Sites ; Carbon Monoxide/chemistry/*metabolism ; Crystallography, X-Ray ; Heme/chemistry/metabolism ; Histidine/chemistry/metabolism ; Hydrogen Bonding ; Iron/chemistry/metabolism ; Ligands ; Metmyoglobin/chemistry ; Models, Molecular ; Myoglobin/*analogs & derivatives/*chemistry/metabolism ; Nitrogen/chemistry/metabolism ; Protein Conformation ; Protein Structure, Secondary ; Temperature ; Valine/chemistry/metabolism
    Print ISSN: 0036-8075
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  • 59
    Publication Date: 1999-12-03
    Description: The actin-binding protein gelsolin is involved in remodeling the actin cytoskeleton during growth-factor signaling, apoptosis, cytokinesis, and cell movement. Calcium-activated gelsolin severs and caps actin filaments. The 3.4 angstrom x-ray structure of the carboxyl-terminal half of gelsolin (G4-G6) in complex with actin reveals the basis for gelsolin activation. Calcium binding induces a conformational rearrangement in which domain G6 is flipped over and translated by about 40 angstroms relative to G4 and G5. The structural reorganization tears apart the continuous beta sheet core of G4 and G6. This exposes the actin-binding site on G4, enabling severing and capping of actin filaments to proceed.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Robinson, R C -- Mejillano, M -- Le, V P -- Burtnick, L D -- Yin, H L -- Choe, S -- New York, N.Y. -- Science. 1999 Dec 3;286(5446):1939-42.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Structural Biology Laboratory, Salk Institute for Biological Studies, Post Office Box 85800, San Diego, CA 92186-5800, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/10583954" target="_blank"〉PubMed〈/a〉
    Keywords: Actins/chemistry/*metabolism ; Binding Sites ; Crystallography, X-Ray ; Gelsolin/*chemistry/*metabolism ; Hydrogen Bonding ; Models, Molecular ; Protein Binding ; Protein Conformation ; Protein Structure, Secondary ; Protein Structure, Tertiary
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  • 60
    Publication Date: 1999-02-12
    Description: The ETR1 receptor from Arabidopsis binds the gaseous hormone ethylene. A copper ion associated with the ethylene-binding domain is required for high-affinity ethylene-binding activity. A missense mutation in the domain that renders the plant insensitive to ethylene eliminates both ethylene binding and the interaction of copper with the receptor. A sequence from the genome of the cyanobacterium Synechocystis sp. strain 6803 that shows homology to the ethylene-binding domain of ETR1 encodes a functional ethylene-binding protein. On the basis of sequence conservation between the Arabidopsis and the cyanobacterial ethylene-binding domains and on in vitro mutagenesis of ETR1, a structural model for this copper-based ethylene sensor domain is presented.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Rodriguez, F I -- Esch, J J -- Hall, A E -- Binder, B M -- Schaller, G E -- Bleecker, A B -- New York, N.Y. -- Science. 1999 Feb 12;283(5404):996-8.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Botany, 430 Lincoln Drive, University of Wisconsin, Madison, WI 53706, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/9974395" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acid Sequence ; Amino Acid Substitution ; Arabidopsis/genetics/*metabolism ; Bacterial Proteins/chemistry/genetics ; Binding Sites ; Conserved Sequence ; Copper/analysis/*metabolism ; Copper Sulfate/pharmacology ; Cyanobacteria/genetics/metabolism ; Dimerization ; Ethylenes/*metabolism ; Models, Molecular ; Mutagenesis ; Open Reading Frames ; Plant Proteins/chemistry/genetics/isolation & purification/*metabolism ; Receptors, Cell Surface/chemistry/genetics/isolation & purification/*metabolism ; Recombinant Fusion Proteins/chemistry/metabolism ; Saccharomyces cerevisiae ; Silver/metabolism/pharmacology
    Print ISSN: 0036-8075
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    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 61
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1999-01-23
    Description: Partition modules stabilize bacterial plasmids and chromosomes by actively promoting their segregation into daughter cells. The partition module of plasmid P1 is typical and consists of a centromere site, parS, and genes that encode proteins ParA and ParB. We show that ParB can silence genes flanking parS (to which ParB binds), apparently by polymerizing along the DNA from a nucleation site at parS. Wild-type ParB contacts an extensive region of P1 DNA; silencing-defective ParB proteins, which were found to be partition-defective, are less able to spread. Hence, the silenced structure appears to function in partitioning.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Rodionov, O -- Lobocka, M -- Yarmolinsky, M -- New York, N.Y. -- Science. 1999 Jan 22;283(5401):546-9.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Laboratory of Biochemistry, National Cancer Institute, 37 Convent Drive, Bethesda, MD 20892-4255, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/9915704" target="_blank"〉PubMed〈/a〉
    Keywords: Bacterial Proteins/genetics/*metabolism ; Binding Sites ; Centromere/physiology ; Cross-Linking Reagents ; *DNA Helicases ; DNA, Bacterial/genetics/*metabolism ; *DNA-Binding Proteins ; Escherichia coli/*genetics ; Formaldehyde ; *Gene Expression Regulation, Bacterial ; Genes, Reporter ; Mutation ; Plasmids/*genetics/physiology ; Proteins/genetics/metabolism ; Repressor Proteins/genetics/metabolism ; *Trans-Activators
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  • 62
    Publication Date: 1999-11-24
    Description: The human adenovirus serotype 5 (Ad5) is used widely for applications in human gene therapy. Cellular attachment of Ad5 is mediated by binding of the carboxyl-terminal knob of its fiber coat protein to the Coxsackie adenovirus receptor (CAR) protein. However, Ad5 binding to CAR hampers the development of adenovirus vectors capable of specifically targeting (diseased) tissues or organs. Through sequence analysis and mutagenesis, a conserved receptor-binding region was identified on the side of three divergent CAR-binding knobs. The feasibility of simultaneous CAR ablation and redirection of an adenovirus to a new receptor is demonstrated.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Roelvink, P W -- Mi Lee, G -- Einfeld, D A -- Kovesdi, I -- Wickham, T J -- New York, N.Y. -- Science. 1999 Nov 19;286(5444):1568-71.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Research and Development, GenVec Inc., 65 West Watkins Mill Road, Gaithersburg, MD 20879, USA. genecloner@genvec.com〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/10567265" target="_blank"〉PubMed〈/a〉
    Keywords: Adenoviruses, Human/*chemistry/metabolism ; Amino Acid Sequence ; Binding Sites ; Capsid/*chemistry/genetics/*metabolism ; *Capsid Proteins ; Cell Line ; Conserved Sequence ; Coxsackie and Adenovirus Receptor-Like Membrane Protein ; Genetic Vectors ; Humans ; Models, Molecular ; Mutagenesis, Site-Directed ; Point Mutation ; Protein Conformation ; Protein Structure, Secondary ; Receptors, Virus/*metabolism ; Sequence Deletion ; Transfection ; Tumor Cells, Cultured
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  • 63
    Publication Date: 1999-02-26
    Description: Signaling by guanine nucleotide-binding proteins (G proteins) involves sequential protein-protein interactions. G protein-betagamma subunit (Gbetagamma) interactions with phospholipase C-beta2 (PLC-beta2) were studied to determine if all Gbeta contacts are required for signaling. A peptide encoding Gbeta amino acid residues 86 to 105 stimulated PLC-beta2. Six residues (96 to 101) within this sequence could transfer signals and thus constitute a core signal transfer region. Another peptide, encoding Gbeta amino acid residues 115 to 135, did not substantially stimulate PLC-beta2 by itself but inhibited Gbetagamma stimulation, indicating that residues 115 to 135 constitute a general binding domain. Resolution of signal transfer regions from general binding domains indicates that all protein-protein contacts are not required for signal transfer and that it may be feasible to synthesize agonists and antagonists that regulate intracellular signal flow.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Buck, E -- Li, J -- Chen, Y -- Weng, G -- Scarlata, S -- Iyengar, R -- DK-38761/DK/NIDDK NIH HHS/ -- GM-43125/GM/NIGMS NIH HHS/ -- GM-54508/GM/NIGMS NIH HHS/ -- etc. -- New York, N.Y. -- Science. 1999 Feb 26;283(5406):1332-5.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Pharmacology, Mount Sinai School of Medicine, New York, NY 10029, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/10037604" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acid Substitution ; Binding Sites ; Enzyme Activation ; GTP-Binding Proteins/*chemistry/genetics/*metabolism ; Isoenzymes/*metabolism ; Mutagenesis, Site-Directed ; Peptide Fragments/metabolism/pharmacology ; Phospholipase C beta ; Protein Binding ; Recombinant Proteins/metabolism ; *Signal Transduction ; Type C Phospholipases/*metabolism
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  • 64
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1999-10-16
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Gerstein, M -- Chothia, C -- New York, N.Y. -- Science. 1999 Sep 10;285(5434):1682-3.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Molecular Biophysics and Biochemistry Department, Yale University, New Haven, CT 06520, USA. mark.gerstein@yale.edu〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/10523185" target="_blank"〉PubMed〈/a〉
    Keywords: Aspartic Acid/metabolism ; Bacterial Physiological Phenomena ; Bacteriorhodopsins/chemistry/metabolism ; Binding Sites ; Cell Membrane/chemistry/*metabolism ; Chemotaxis ; Crystallography, X-Ray ; Dimerization ; Electron Spin Resonance Spectroscopy ; Membrane Proteins/chemistry/metabolism ; Models, Biological ; Protein Conformation ; Protein Structure, Secondary ; Receptors, Amino Acid/*chemistry/*metabolism ; Receptors, Nicotinic/chemistry/metabolism ; *Signal Transduction ; Solubility
    Print ISSN: 0036-8075
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  • 65
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1999-01-05
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉John, S -- Workman, J L -- New York, N.Y. -- Science. 1998 Dec 4;282(5395):1836-7.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Howard Hughes Medical Institute and Department of Biochemistry and Molecular Biology, Pennsylvania State University, University Park, PA 16802, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/9874634" target="_blank"〉PubMed〈/a〉
    Keywords: Adenosine Triphosphatases/chemistry ; Animals ; Binding Sites ; Chromatin/chemistry/*genetics/metabolism ; Histones/metabolism ; Humans ; Models, Genetic ; Nucleosomes/metabolism ; Promoter Regions, Genetic ; RNA Polymerase II/metabolism ; Templates, Genetic ; Transcription Factors/chemistry/*metabolism ; *Transcription, Genetic
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  • 66
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    Entomologia experimentalis et applicata 92 (1999), S. 205-216 
    ISSN: 1570-7458
    Keywords: Samea multiplicalis ; Spodoptera pectinicornis ; Pistia stratiotes ; waterlettuce ; nitrogen utilization efficiency ; compensatory feeding ; nitrogen ; biological control of weeds
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Compensatory responses of caterpillars fed low quality food include increased consumption and utilization of essential nutrients. Information about an insect's responses to nutritional challenges from their host plants could benefit weed biological control efforts in the selection and establishment of new agents. The target weed, Pistia stratiotes L. (Araceae) is a floating aquatic plant that has relatively low nitrogen levels which are further diluted with high water content. Efforts to establish the insect Spodoptera pectinicornis (Hampson) (Lepidoptera: Noctuidae) for biological control of P. stratiotes could benefit by examining the nutritional responses of a similar widely established lepidopteran species, Samea multiplicalis (Guenèe) (Lepidoptera: Pyralidae). Larvae of this species were fed leaves of P. stratiotes plants that had been fertilized (NPK) at high and low rates. The leaves of the fertilized plants had a 4.3-fold increase in nitrogen (dry weight) and a 1.6-fold increase in water content. The results suggest that no compensatory increases occurred in larvae fed leaves from the low fertilized plants as no changes were found in fresh mass consumption or nitrogen utilization efficiency. Consequently, development time from second-third instars to pupation was delayed about 3 days compared with larvae fed the high nitrogen leaves. Furthermore, consumption of nitrogen was only 30% and its accumulation into larval tissues was only 60% compared with the larvae fed the high fertilized leaves. The resulting larvae had both a final biomass and a growth rate that were reduced by 40%. Regardless of plant fertilizer level, the larvae fed at a rate 5–10 times greater than that of similar lepidopteran species consuming either low or high quality diets, suggesting that the S. multiplicalis larvae may be functioning at their biological limit for ingesting food.
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  • 67
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    Entomologia experimentalis et applicata 92 (1999), S. 165-177 
    ISSN: 1570-7458
    Keywords: Chrysomelidae ; herbivory ; Asteraceae ; life history ; nitrogen ; plant quality ; season
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Phytophagous insects which feed on the leaves of herbaceous host plants have to adapt their life histories to the fact that protein nitrogen is usually highest in growing tissues in spring. We monitored field populations of larvae and adults of three chrysomelid species (Galeruca tanaceti (L.) (main host Achillea millefolium (L.) Yarrow), Cassida rubiginosa (Mueller) (main host Cirsium arvense (L.) Scop.) and Oreina luctuosa (Suffrian) (host Centaurea scabiosa (L.)) together with the amount of protein nitrogen of their food resources and host plant biomass. As expected, the development of host quality, measured as concentration of protein nitrogen, and host plant biomass showed inverse trends during the season. The euryphagous G. tanaceti attacks Achillea early and profits from high nitrogen concentrations in the leaves. Occasional overexploitations of local populations of Achillea are compensated by the capacity to move to other host species. In C. rubiginosa, a species with a host range restricted to the Cardueae, the main larval feeding activity is postponed to a period when the nitrogen content of the host leaves had dropped to 50% of its initial value, but when host plant biomass had increased by 30%. In the monophagous O. luctuosa the larval development is synchronized with a still later phase of host phenology, at which the nitrogen content is below 50% but plant biomass has reached its maximum. There seem to be selection factors, which oppose the use of high quality food in spring and which force the latter two species to postpone their larval development to a later time in the year. This could be caused by numerous factors like, for example, mean daytime temperature. Later in the season the larvae have to cope with the low quality of their host plants. They have, however, the advantage of large quantities of food available. A laboratory study with adults and mature larvae of O. luctuosa shows that this species can overcome low levels of protein nitrogen either by selecting younger leaves with higher nitrogen concentrations or by increasing the daily food consumption rate (RCR) on leaves with a low level of nitrogen and by a prolongation of the feeding period. In this way the larvae compensate the effect of lower daily growth rates (RGR) and a lower food conversion index (ECI) on poor food quality: Regardless of the level of protein nitrogen there was no statistically significant difference in total gain of weight during the third-instar feeding period and in the weight at the end of the third larval stage. The three investigated chrysomelids show that there exists a broad spectrum of adaptations to overcome the dilemma of variable food quality.
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  • 68
    ISSN: 1572-879X
    Keywords: adsorption ; adsorption isotherms ; dinitrogen ; FTIR spectroscopy ; geminal species ; NaY ; nitrogen ; zeolites
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Adsorption of N2 on NaY zeolites at 85 K and equilibrium pressures higher than 1 kPa results in the formation of geminal dinitrogen complexes characterized by an IR band at 2333.5 cm−1 (2255.4 cm−1 after adsorption of 15N2). With decreasing equilibrium pressure the complexes tend to loose one N2 ligand, thus forming linear species characterized by an IR band at 2336.8 cm−1 (2258.7 cm−1 after adsorption of 15N2). All species disappear completely after evacuation. Co-adsorption of N2 and CO revealed that the dinitrogen complexes are formed on Na+ cations. The changes in the concentrations of the linear and geminal N2 species with the changes in the equilibrium pressure are excellently described by equations of adsorption isotherms proposed earlier for mono- and di-carbonyls.
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  • 69
    ISSN: 1572-8757
    Keywords: kinetics ; isotope-exchange ; nitrogen ; adsorption ; methane ; zeolite ; equilibria
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Physics , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract The Isotope Exchange Technique (IET) was used to simultaneously measure pure and binary gas adsorption equilibria and kinetics (self-diffusivities) of CH4 and N2 on pelletized 4A zeolite. The experiment was carried out isothermally without disturbing the adsorbed phase. CH4 was selectively adsorbed over N2 by the zeolite because of its higher polarizability. The multi-site Langmuir model described the pure gas and binary adsorption equilibria fairly well at three different temperatures. The selectivity of adsorption of CH4 over N2 increased with increasing pressure at constant gas phase composition and temperature. This curious behavior was caused by the differences in the sizes of the adsorbates. The diffusion of CH4 and N2 into the zeolite was an activated process and the Fickian diffusion model described the uptake of both pure gases and their mixtures. The self-diffusivity of N2 was an order of magnitude larger than that for CH4. The pure gas self-diffusivities for both components were constants over a large range of surface coverages (0 〈 θ 〈 0.5). The self-diffusivities of CH4 and N2 from their binary mixtures were not affected by the presence of each other, compared to their pure gas self-diffusivities at identical surface coverages.
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  • 70
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    Nutrient cycling in agroecosystems 53 (1999), S. 209-218 
    ISSN: 1573-0867
    Keywords: cattle slurry ; fertilizer splitting ; nitrogen ; recovery ; residual nitrogen ; Zea mays L
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The recovery of soil mineral nitrogen (N) by crops, and its subsequent utilisation for dry matter (DM) production may be increased when the application of N is postponed until after crop emergence. The significance of this strategy for silage maize was studied in nine field experiments on Dutch sandy soils from 1983 to 1988. In five experiments the effect of slurry applied before planting at a rate of circa 66 m3 ha-1, was compared to the effect of a similar rate of which half was applied before planting and half at the 4–6 leaf stage. In the 4-6 leaf stage slurry was either injected or banded. In four other experiments the effect of mineral fertilizer-N splitting was studied. In these experiments, 30 m3 ha-1 cattle slurry, applied before planting, was supplemented with mineral fertilizer-N at rates ranging from 40 to 160 kg ha-1, either fully applied before crop emergence or split. When split, 40 kg ha-1 of the mineral fertilizer-N rate was banded at the 4–6 leaf stage. According to balance sheet calculations, substantial losses of slurry N and mineral fertilizer-N occurred during the growing season. Losses were compensated for, however, by apparent mineralization, ranging from 0.34 to 0.77 kg N ha-1 day-1. Split applications of cattle slurry had a significant positive effect on the DM yield in two out of five experiments compared to the conventional non-split application, but only when the post-emergence slurry application was banded which is no longer in accordance with present legislation. Split applications of mineral fertilizer-N had a significant positive effect in one experiment where rainfall was excessive but not in the others. The results provide insufficient evidence to recommend farmers to split applications. Soil mineral N sampling at the 4–6 leaf stage should hence be considered a control on the appropriateness of early N applications after exceptional weather conditions rather than a routine observation on which the post-emergence N dressing is to be based in a deliberate splitting strategy. Our data suggest that the financial return of a 40 kg ha-1 supplementation with mineral fertilizer-N, was questionable when more than 175 kg N ha-1 were found in the upper 0.6 m soil layer at the 4–6 leaf stage.
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  • 71
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    Nutrient cycling in agroecosystems 53 (1999), S. 259-267 
    ISSN: 1573-0867
    Keywords: farming systems ; nitrogen ; nitrogen budgets ; sustainability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Three approaches to nitrogen budgeting were developed and their ability to quantitatively describe nitrogen cycling in a fertilizer based and a grass–clover based beef system tested. Budgets ranged in complexity from the Economic Input:Output (EIO) budget, which accounted simply for purchases and sales of nitrogen over the farmgate, through the Biological Input:Output (BIO) budget, which included estimates of biological nitrogen fixation and attempted to partition losses into leaching and gaseous forms, to the Transfer:Recycle:Input:Output (TRIO) budget, which also accounted for key soil processes. Nitrogen unaccounted for in the fertilized system decreased with increasing budget complexity (285, 212 and 188 kg ha-1 yr-1 unaccounted for by the EIO, BIO and TRIO budgets, respectively). In the legume based grass–clover system, the EIO budget did not accurately describe total nitrogen inputs as it did not include 146 kg ha-1 yr-1 from symbiotic nitrogen fixation. In the grass–clover system, nitrogen unaccounted for was again greater using the BIO than the TRIO budget (103 and 79 kg ha-1 yr-1, respectively). In conclusion, the most complex budgeting approach (TRIO) was able to account for the fate of a greater proportion of nitrogen inputs than the simpler approaches. However, the perceived success of the different approaches was strongly dependent on the precise objective.
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  • 72
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    Nutrient cycling in agroecosystems 55 (1999), S. 1-6 
    ISSN: 1573-0867
    Keywords: chlorophyll meter ; irrigation ; LAI ; nitrogen ; Spring Wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract A Spring Wheat crop was grown using three irrigation levels and nitrogen rate applications to evaluate chlorophyll meter measurements as a possible nitrogen nutrition index for modelling. These measurements yielded the most reliable indications at Zadoks GS45. The lower limit indicating severe nitrogen deficiency in the leaves was approximately 35 SPAD units while the upper limit of 45 SPAD units, indicated an excess consumption.
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  • 73
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    Nutrient cycling in agroecosystems 55 (1999), S. 89-94 
    ISSN: 1573-0867
    Keywords: algae ; flooded soils ; N cycling ; nitrogen ; 15N ; rice
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Algal N labelled with 15N added to a flooded soil in laboratory columns without plants was studied to determine the changes over time in the fate of N assimilated by algae and to study how its fate is affected by (a) exclusion of light simulating complete closure of the rice canopy, and (b) addition of fertilizer-NH4 *. In the light but with no added fertilizer-N there was little net mineralization of the added algal N during the first 4 weeks, but after 8 weeks 42% had been mineralized, of which 95% was denitrified. Exclusion of light caused net mineralization to proceed more rapidly in the first 4 weeks due to the death of algal cells and lowered reassimilation. After 8 weeks 51% had been mineralized, of which 54% was denitrified, 16% volatilized and 30% was present as KCl exchangeable NH4 +-N. Application of fertilizer-NH4 + apparently caused mineralization of 25% of the algal N within one week but the results were probably affected by pool substitution in which labelled N mineralized to NH4 +-N was diluted with fertilizer – NH+ 4 and then immobilized leaving more labelled NH4–N in the mineral pool. After 8 weeks, 42% of algal N had been mineralized, of which 69% was estimated to have been denitrified, 19% lost through NH3 volatilization and 12% remained as extracted NH4 ++NO- 3. Uptake of N by a rice crop would reduce the gaseous losses. Algal N was mineralized quickly enough to be available during the growing season of a rice crop and, depending on field conditions, algae may have a role in assimilating N and protecting it from loss as well as being a major driving force for NH3 volatilization through diurnal increases in pH.
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  • 74
    ISSN: 1572-9702
    Keywords: tomato plants ; susceptibility ; mite ; tridecan-2-one ; nitrogen ; potasium
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The objective of this work was to study the effect of NK fertilization levels and canopy height on the resistance of Lycopersicon hirsutum and Lycopersicon esculentum to Aculops lycopersici (Acari: Eriophydae). The effects of NK fertilization levels and canopy height in the leaf size and density of trichomes and their effects on tridecan-2-one (2-TD) and undecan-2-one (2-UD) limiting the attack of A. lycopersici on tomato plants were assessed. Different NK fertilization levels had no effect on the resistance of L. hirsutum to A. lycopersici. No significant differences were found in attack rates of this mite on leaves of the top and median parts of L. hirsutum canopy. The type and density of trichomes were the main determining factor of A. lycopersici attack on tomato plants. High trichome densities and type VI glandular trichomes which produce tridecan-2-one are important resistance factors on tomato plants. L. hirsutum showed a high resistance level to A. lycopersici due to high densities of type VI glandular trichomes and consequently higher levels of tridecan-2-one in its leaves.
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  • 75
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    Journal of materials synthesis and processing 7 (1999), S. 311-319 
    ISSN: 1573-4870
    Keywords: Iron ; carbon ; nitrogen ; microstructure ; characterization ; HIP-drip
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract A new processing technique makes nitrogen alloying possible by adding nitrogen under elevated nitrogen pressure to prealloyed Fe-C ingots during continuous casting, producing a whole new class of precipitation-free, iron–carbon–nitrogen alloys. When both carbon and nitrogen bulk concentration levels exceeded 0.5 wt%, a duplex fcc-/(bcc-bct-) Fe microstructure resulted that is iron carbide- and nitride-free. With increasing carbon and nitrogen concentrations, there was an increase in the retained fcc-Fe phase. In cooling rate studies, increasing carbon and nitrogen concentrations shifted the knee of the fcc-Fe-to-bcc-Fe phase time–temperature–transformation (T–T–T) curve to longer times. Hardness, compression strength, and wear resistance increased with increasing carbon and nitrogen concentrations and were superior to iron–carbon alloys without the nitrogen addition.
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  • 76
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    Potato research 42 (1999), S. 559-568 
    ISSN: 1871-4528
    Keywords: plastic mulch ; transplanting ; nitrogen ; planting depth ; seed tuber weight ; physiological age ; radiation conversion efficiency ; harvest index
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary In many seed potato producing areas, micro- and minitubers are too small for direct planting as seed tubers in the field. Such use of these propagules can, however, be feasible if the crop's growth and development can be advanced. Increasing light interception, harvest index and yield of useable progeny tubers has been proved possible with plastic mulch and pre-planting of small tubers in a greenhouse. High amounts of nitrogen (up to 180 kg ha−1) or deep planting (up to 9 cm) were less effective. Using older or pre-sprouted micro- or minitubers may be beneficial, because this might increase the number of sprouts per mother tuber (and thus stems per plant) or advance the growth of sprouts or stems. However, this would require even more careful management, due to the weakness of these sprouts and stems. Micro- and minitubers should be as large as feasible when used for direct planting in the field.
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  • 77
    ISSN: 1573-5125
    Keywords: denitrification ; nature restoration ; nitrogen ; phosphorus ; riparian areas ; sedimentation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In Denmark, as in many other European countries, the diffuse losses of nitrogen (N) and phosphorus (P) from the rural landscape are the major causes of surface water eutrophication and groundwater pollution. The export of total N and total P from the Gjern river basin amounted to 18.2 kg ha−1 and 0.63 kg P ha−1 during June 1994 to May 1995. Diffuse losses of N and P from agricultural areas were the main nutrient source in the river basin contributing 76% and 51%, respectively, of the total export. Investigations of nutrient cycling in the Gjern river basin have revealed the importance of permanent nutrient sinks (denitrification and overbank sedimentation) and temporary nutrient storage in watercourses. Temporary retention of N and P in the watercourses thus amounted to 7.2–16.1 g N m−2 yr−1 and 3.7–8.3 g P m−2 yr−1 during low-flow periods. Deposition of P on temporarily flooded riparian areas amounted from 0.16 to 6.50 g P m−2 during single irrigation and overbank flood events, whereas denitrification of nitrate amounted on average to 7.96 kg N yr−1 per running metre watercourse in a minerotrophic fen and 1.53 kg N yr−1 per linear metre watercourse in a wet meadow. On average, annual retention of N and P in 18 Danish shallow lakes amounted to 32.5 g N m−2 yr−1 and 0.30 g P m−2 yr−1, respectively, during the period 1989–1995. The results indicate that permanent nutrient sinks and temporary nutrient storage in river systems represent an important component of river basin nutrient budgets. Model estimates of the natural retention potential of the Gjern river basin revealed an increase from 38.8 to 81.4 tonnes yr−1 and that P-retention increased from −0.80 to 0.90 tonnes yr−1 following restoration of the water courses, riparian areas and a shallow lake. Catchment management measures such as nature restoration at the river basin scale can thus help to combat diffuse nutrient pollution.
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  • 78
    ISSN: 1573-5052
    Keywords: mineralization ; nitrogen ; phosphorus ; salinity ; stress
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Plant zonation patterns across New England salt marshes have been investigated for years, but how nutrient availability differs between zones has received little attention. We investigated how N availability, P availability, and plant N status varied across Juncus gerardii, Spartina patens, and mixed forb zones of a Northern New England high salt marsh. We also investigated relationships between several edaphic factors and community production and diversity across the high marsh. P availability, soil salinity, and soil moisture were higher in the mixed forb zone than in the two graminoid zones. NH+ 4-N availability was highest in the J. gerardii zone, but NO− 3-N availability and mid season net N mineralization rates did not vary among zones. Plant tissue N concentrations were highest in the mixed forb zone and lowest in the S. patens zone, reflecting plant physiologies more so than soil N availability. Community production was highest in the J. gerardii zone and was positively correlated with N availability and negatively correlated with soil moisture. Plant species diversity was highest in the mixed forb zone and was positively correlated with P availability and soil salinity. Thus, nutrient availability, plant N status, and plant species diversity varied across zones of this high marsh. Further investigation is needed to ascertain if soil nutrient availability influences or is a result of the production and diversity differences that exist between vegetation zones of New England high salt marshes.
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  • 79
    ISSN: 1573-5125
    Keywords: denitrification ; eutrophication ; estuary ; nitrogen ; sediment-water exchange
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In this review of sediment denitrification in estuaries and coastal ecosystems, we examine current denitrification measurement methodologies and the dominant biogeochemical controls on denitrification rates in coastal sediments. Integrated estimates of denitrification in coastal ecosystems are confounded by methodological difficulties, a lack of systematic understanding of the effects of changing environmental conditions, and inadequate attention to spatial and temporal variability to provide both seasonal and annual rates. Recent improvements in measurement techniques involving 15 N techniques and direct N2 concentration changes appear to provide realistic rates of sediment denitrification. Controlling factors in coastal systems include concentrations of water column NO 3 − , overall rates of sediment carbon metabolism, overlying water oxygen concentrations, the depth of oxygen penetration, and the presence/absence of aquatic vegetation and macrofauna. In systems experiencing environmental change, either degradation or improvement, the importance of denitrification can change. With the eutrophication of the Chesapeake Bay, the overall rates of denitrification relative to N loading terms have decreased, with factors such as loss of benthic habitat via anoxia and loss of submerged aquatic vegetation driving such effects.
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  • 80
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    Aquatic ecology 33 (1999), S. 55-64 
    ISSN: 1573-5125
    Keywords: estuaries ; nitrogen ; oxygen depletion ; phosphorus ; regression model ; vertical mixing
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In a detailed analysis of oxygen saturation in a shallow Danish estuary it was possible to separate the effect of meteorological forcings (i.e. wind and solar radiation) and nutrient loads on oxygen depletion in bottom water. Regression analysis showed that oxygen saturation tied to nitrogen load rather than to phosphorus load. During summer periods of stratification the oxygen saturation could be attributed to the time elapsed after the onset of stratification and the accumulated nitrogen loading 10 month prior to measurement. Using a 10-year meteorological database and an empirical model it was calculated that a 25% reduction in nitrogen loading would reduce the number of days with severe oxygen depletion (i.e. 〈15% of saturation) by more than 50%.
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  • 81
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    European journal of plant pathology 105 (1999), S. 61-76 
    ISSN: 1573-8469
    Keywords: core sampling ; foliar nutrient concentrations ; minirhizotrons ; nitrogen ; phosphorus ; potassium ; Rhizolab
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Potato-cyst nematodes (Globodera pallida) cause severe yield losses in potato. Plants infected with potato-cyst nematodes generally have reduced concentrations of nitrogen, phosphorus and potassium in the foliage. This study investigated whether reduced growth of nematode-infected potato is caused by nutrient limitation. Experiments in the field and in containers showed that phosphorus concentration correlated best with total crop biomass at early stages of growth. The role of phosphorus in nematode damage was further investigated in the field and in the Wageningen Rhizolab. The experimental field was infested with potato-cyst nematodes and two levels of nematode density were established by fumigation with a nematicide. Prior applications of calcium carbonate resulted in pHKCl levels of 4.8 and 6.1. Two levels of phosphorus fertiliser were applied: either 0 or 225 kg P ha−1. In the Wageningen Rhizolab, soil of both pH levels from the field was used after treatment with 1 MRad gamma irradiation to kill the nematodes. Subsequently, half of the soil was inoculated with cysts to give a nematode density of 30 viable juveniles per gram of soil. In the field, nine weeks after planting, the total crop biomass ranged from 107 g m−2 for the treatment with nematodes at pHKCl 6.1 without phosphorus fertiliser to 289 g m−2 for the fumigated treatment at pHKCl 4.8 with phosphorus fertiliser. The differences in total biomass for the various treatments were explained by differences in foliar phosphorus concentration. Nematodes induced or aggravated P deficiency and reduced total biomass. This was not the only damage mechanism as at high, non-limiting levels of foliar phosphorus concentration, nematodes still reduced total biomass. In the Wageningen Rhizolab, directly after planting, the number of roots visible against minirhizotrons was reduced by nematodes. However, the increase of root number in the nematode treatment continued longer than in the control, until root number was higher than that of the control. The compensary root growth of the nematode treatment was restricted to the top 30 cm and nematodes reduced rooting depth. High soil pH reduced growth, mainly by reducing the availability of phosphate. Both nematodes and high soil pH reduced nutrient uptake per unit root length. Our results lead us to suggest an interaction between nematodes and soil pH, with nematode damage being higher at pHKCl 6.1 than at pHKCl 4.8.
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  • 82
    ISSN: 1573-868X
    Keywords: Osaka Bay ; sediment ; carbon ; nitrogen ; organic matter ; stable isotope ratio ; terrestrial organic matter ; TOC ; POC
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract Carbon and nitrogen stable isotope ratios (δ13C and δ15N) of surface sediments were measured within Osaka Bay, in the Seto Inland Sea in Japan, in order to better understand the sedimentation processes operating on both terrestrial and marine organic matter in the Bay. The δ13C and δ15N of surface sediments in the estuary of the Yodo River were less than −23‰ and 5‰ respectively, but increased in the area up to about 10 km from the river mouth. At greater distances they became constant (giving δ13C of about −20‰ and δ15N about 6‰). It can be concluded that large amounts of terrestrial organic matter exist near the mouth of the Yodo River. Stable isotope ratios in the estuary of the Yodo River within 10 km of the river mouth were useful indicators allowing study of the movement of terrestrial organic matter. Deposition rates for total organic carbon (TOC) and total nitrogen (TN) over the whole of the Bay were estimated to be 63,100 ton C/year and 7,590 ton N/year, respectively. The deposition rate of terrestrial organic carbon was estimated to be 13,200 (range 2,000–21,500) ton C/year for the whole of Osaka Bay, and terrestrial organic carbon was estimated to be about 21% (range 3–34) of the TOC deposition rate. The ratio of the deposition rate of terrestrial organic carbon to the rate inflow of riverine TOC and particulate organic carbon (POC) were estimated to be 19% (range 3–31) and 76% (range 12–100), respectively.
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  • 83
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    Water resources management 13 (1999), S. 303-314 
    ISSN: 1573-1650
    Keywords: economics ; irrigation ; nitrogen ; nutrients ; wastewater
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying , Geography
    Notes: Abstract The optimal wastewater treatment level is affected by costs, hazards and benefits. Lowering the wastewater treatment level decreases fertilization costs because of the increased levels of available nutrients left in the water, and irrigation costs decrease if water prices reflect the lower treatment costs. Agricultural yields and/or prices may decrease according to differences between levels of nutrients needed by crops and those available in wastewater. The present article focuses on determination of monthly optimal treatment levels and of the mix of crops calculated to maximize agricultural incomes, according to farmers' point of view. It does not reflect the national point-view focusing on maximization of net national benefits considering also environmental hazards. The methodology appears in Haruvy (1994) and application will be presented in another article (Haruvy et al., 1999).
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  • 84
    ISSN: 1573-515X
    Keywords: Baltic Sea ; cyanobacteria ; estuaries ; grazing ; iron ; lakes ; molybdenum ; nitrogen ; nitrogen fixation ; nitrogen limitation ; Zooplankton
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract Explaining the nearly ubiquitous absence of nitrogen fixation by planktonic organisms in strongly nitrogen-limited estuaries presents a major challenge to aquatic ecologists. In freshwater lakes of moderate productivity, nitrogen limitation is seldom maintained for long since heterocystic, nitrogen-fixing cyanobacteria bloom, fix nitrogen, and alleviate the nitrogen limitation. In marked contrast to lakes, this behavior occurs in only a few estuaries worldwide. Primary production is limited by nitrogen in most temperate estuaries, yet no measurable planktonic nitrogen fixation occurs. In this paper, we present the hypothesis that the absence of planktonic nitrogen fixers from most estuaries is due to an interaction of bottom-up and top-down controls. The availability of Mo, a trace metal required for nitrogen fixation, is lower in estuaries than in freshwater lakes. This is not an absolute physiological constraint against the occurrence of nitrogen-fixing organisms, but the lower Mo availability may slow the growth rate of these organisms. The slower growth rate makes nitrogen-fixing cyanobacteria in estuaries more sensitive to mortality from grazing by Zooplankton and benthic organisms. We use a simple, mechanistically based simulation model to explore this hypothesis. The model correctly predicts the timing of the formation of heterocystic, cyanobacterial blooms in freshwater lakes and the magnitude of the rate of nitrogen fixation. The model also correctly predicts that high Zooplankton biomasses in freshwaters can partially suppress blooms of nitrogen-fixing cyanobacteria, even in strongly nitrogen-limited lakes. Further, the model indicates that a relatively small and environmentally realistic decrease in Mo availability, such as that which may occur in seawater compared to freshwaters due to sulfate inhibition of Mo assimilation, can suppress blooms of heterocystic cyanobacteria and prevent planktonic nitrogen fixation. For example, the model predicts that at a Zooplankton biomass of 0.2 mg l−1, cyanobacteria will bloom and fix nitrogen in lakes but not in estuaries of full-strength seawater salinity because of the lower Mo availability. Thus, the model provides strong support for our hypothesis that bottom-up and top-down controls may interact to cause the absence of planktonic nitrogen fixation in most estuaries. The model also provides a basis for further exploration of this hypothesis in individual estuarine systems and correctly predicts that planktonic nitrogen fixation can occur in low salinity estuaries, such as the Baltic Sea, where Mo availability is greater than in higher salinity estuaries.
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  • 85
    ISSN: 1573-515X
    Keywords: N15 ; nitrogen ; nutrient cycling ; plants ; stable isotopes ; soil ; temperate forest ; tropical forest
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract Several lines of evidence suggest that nitrogen in most tropical forests is relatively more available than N in most temperate forests, and even that it may function as an excess nutrient in many tropical forests. If this is correct, tropical forests should have more open N cycles than temperate forests, with both inputs and outputs of N large relative to N cycling within systems. Consequent differences in both the magnitude and the pathways of N loss imply that tropical forests should in general be more 15N enriched than are most temperate forests. In order to test this hypothesis, we compared the nitrogen stable isotopic composition of tree leaves and soils from a variety of tropical and temperate forests. Foliar δ15N values from tropical forests averaged 6.5‰ higher than from temperate forests. Within the tropics, ecosystems with relatively low N availability (montane forests, forests on sandy soils) were significantly more depleted in 15N than other tropical forests. The average δ15N values for tropical forest soils, either for surface or for depth samples, were almost 8‰ higher than temperate forest soils. These results provide another line of evidence that N is relatively abundant in many tropical forest ecosystems.
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  • 86
    ISSN: 1573-515X
    Keywords: estuaries ; lakes ; marine ; nitrogen ; phosphorus ; rivers ; streams ; temperate ; tropics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract Published data and analyses from temperate and tropical aquatic systems are used to summarize knowledge about the potential impact of land-use alteration on the nitrogen biogeochemistry of tropical aquatic ecosystems, identify important patterns and recommend key needs for research. The tropical N-cycle is traced from pre-disturbance conditions through the phases of disturbance, highlighting major differences between tropical and temperate systems that might influence development strategies in the tropics. Analyses suggest that tropical freshwaters are more frequently N-limited than temperate zones, while tropical marine systems may show more frequent P limitation. These analyses indicate that disturbances to pristine tropical lands will lead to greatly increased primary production in freshwaters and large changes in tropical freshwater communities. Increased freshwater nutrient flux will also lead to an expansion of the high production, N- and light-limited zones around river deltas, a switch from P- to N-limitation in calcareous marine systems, with large changes in the community composition of fragile mangrove and reef systems. Key information gaps are highlighted, including data on mechanisms of nutrient transport and atmospheric deposition in the tropics, nutrient and material retention capacities of tropical impoundments, and N/P coupling and stoichiometric impacts of nutrient supplies on tropical aquatic communities. The current base of biogeochemical data suggests that alterations in the N-cycle will have greater impacts on tropical aquatic ecosystems than those already observed in the temperate zone.
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  • 87
    ISSN: 1573-515X
    Keywords: Baltic Sea ; cyanobacteria ; estuaries ; grazing ; iron ; lakes ; molybdenum ; nitrogen ; nitrogen fixation ; nitrogen limitation ; zooplankton
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract Explaining the nearly ubiquitous absence of nitrogen fixation by planktonic organisms in strongly nitrogen-limited estuaries presents a major challenge to aquatic ecologists. In freshwater lakes of moderate productivity, nitrogen limitation is seldom maintained for long since heterocystic, nitrogen-fixing cyanobacteria bloom, fix nitrogen, and alleviate the nitrogen limitation. In marked contrast to lakes, this behavior occurs in only a few estuaries worldwide. Primary production is limited by nitrogen in most temperate estuaries, yet no measurable planktonic nitrogen fixation occurs. In this paper, we present the hypothesis that the absence of planktonic nitrogen fixers from most estuaries is due to an interaction of bottom-up and top-down controls. The availability of Mo, a trace metal required for nitrogen fixation, is lower in estuaries than in freshwater lakes. This is not an absolute physiological constraint against the occurrence of nitrogen-fixing organisms, but the lower Mo availability may slow the growth rate of these organisms. The slower growth rate makes nitrogen-fixing cyanobacteria in estuaries more sensitive to mortality from grazing by zooplankton and benthic organisms. We use a simple, mechanistically based simulation model to explore this hypothesis. The model correctly predicts the timing of the formation of heterocystic, cyanobacterial blooms in freshwater lakes and the magnitude of the rate of nitrogen fixation. The model also correctly predicts that high zooplankton biomasses in freshwaters can partially suppress blooms of nitrogen-fixing cyanobacteria, even in strongly nitrogen-limited lakes. Further, the model indicates that a relatively small and environmentally realistic decrease in Mo availability, such as that which may occur in seawater compared to freshwaters due to sulfate inhibition of Mo assimilation, can suppress blooms of heterocystic cyanobacteria and prevent planktonic nitrogen fixation. For example, the model predicts that at a zooplankton biomass of 0.2 mg l−1, cyanobacteria will bloom and fix nitrogen in lakes but not in estuaries of full-strength seawater salinity because of the lower Mo availability. Thus, the model provides strong support for our hypothesis that bottom-up and top-down controls may interact to cause the absence of planktonic nitrogen fixation in most estuaries. The model also provides a basis for further exploration of this hypothesis in individual estuarine systems and correctly predicts that planktonic nitrogen fixation can occur in low salinity estuaries, such as the Baltic Sea, where Mo availability is greater than in higher salinity estuaries.
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  • 88
    ISSN: 1573-5036
    Keywords: ectomycorrhizae ; Eucalyptus regnans ; forest burns ; nitrogen ; phosphorus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract This study was conducted to compare the effects on the growth of Eucalyptus regnans seedlings of unheated soil and soil heated to different extents (as indicated by soil colour–bright red or black) in burnt logging coupes, and to separate the effects of heating of the soil on direct nutrient availability and on morphotypes and effectiveness of ectomycorrhizae. Burnt soils were collected from three logging coupes burnt 2, 14 and 25 months previously and unbumt soil from adjacent regrowth forests. Compared to unburnt soil, the early seedling growth was stimulated in black burnt soil from all coupes (burnt 2, 14 and 25 months previously). Seedling growth was generally poor in red burnt soil, especially in soil collected 2 months after burning. However, the concentration of extractable P was extremely high in red burnt soil, especially in soil collected 2 months after burning. In black burnt soil, extractable P was increased in soil 2 months after burning, but not in the soils collected 14 or 25 months after burning. However, both total P content and concentration in seedlings were increased in all collections of black burnt soil. Frequency of ectomycorrhizae was high in seedlings grown in all black burnt soils, but the mycorrhizal mantles were poorly developed in seedlings in black burnt soil collected 2 months after burning. Seedlings were also ectomycorrhizal in red burnt soil, except in soil collected 2 months after burning. Fine root inocula from seedlings grown in black burnt soils collected 14 and 25 months after burning significantly stimulated both seedling growth and P uptake compared with the uninoculated control, whereas the fine root inocula from the seedlings grown in all the other soils did not. These results suggest that, in black burnt soil, both direct nutritional changes and changes in the ectomycorrhizae may contribute to seedling growth promotion after regeneration burns. The generally poor seedling growth in red burnt soils is likely to have been due to N deficiency as the seedlings in these soils were yellow-green and the tissue concentrations of N were significantly lower than in other treatments.
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  • 89
    ISSN: 1573-5036
    Keywords: crop residues ; isotope dilution ; 15N ; nitrogen ; organic matter ; pool substitution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Experiments were carried out to compare the direct approach for estimating crop N uptake from 15N labelled organic inputs, to two indirect approaches, 15N isotope dilution and A value. In the first experiment soils received 25, 50, 75, or 100 mg N kg soil−1 in the form of Casuarina equisitifolia residues in addition to ammonium sulphate fertiliser, to give a total of 100 mg N kg soil−1 added. This was a cross labelling design, thus two matching sets of treatments, were set up, identical in all but the position of the 15N label. Maize (Zea mays L.) plants were grown in the soils amended with residues for 11 weeks and N derived from residues (Ndfr) estimated using the A-value or the direct approach. The A-value approach appeared to significantly overestimate %Ndfr compared to the direct method. In the second experiment contrasting residues were added to soil, fababean (Vicia faba L. var. minor), alfalfa (Medicago sativa L.), soyabean fixing, (Glycine max (L.) Merrill), soyabean non-fixing, barley (Hordeum vulgare L.) and maize. This was also cross-labelling design, labelled and unlabelled residues were used. Maize plants were grown in these soils for 11 weeks and %Ndfr in the maize plants estimated using 15 N isotope dilution and the direct approach. The 15 N isotope dilution approach also overestimated %Ndfr compared to the direct method in this experiment. Pool substitution appeared to be responsible for the discrepancy between the direct and indirect techniques. It was concluded that 15N isotope dilution and A-value approaches as used in these experiments (i.e where residues and 15N label are added simultaneously) were not appropriate techniques for estimating N derived from organic residues in soils.
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  • 90
    ISSN: 1573-5036
    Keywords: nitrogen ; Prunus ; remobilisation ; storage ; uptake
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Two-year old nectarine trees (Prunus persica, Batsch, var. nectarina, cv. Starkredgold on GF305 rootstock) planted in pots each received five applications of 1.0 g 15N labelled urea either from mid May to mid July (early uptake) or from mid August to the beginning of October (late uptake). All trees were supplied with a corresponding amount of unlabelled urea when they did not receive the labelled N. In autumn, all abscised leaves were collected and during winter randomly selected trees were harvested and divided into main organs. The remaining trees were transplanted into similar pots filled with sand; they received no N fertiliser and were harvested in May to evaluate the remobilisation of N. Total N and 15N abundance were determined in each organ. Nectarine trees took up similar amounts of N in the 'early' and in the 'late' period; however, more labelled nitrogen was recovered in the perennial organs during the winter when trees received the labelled N in the 'late' than in the 'early' period. Some 73–80% of the N present in the dormant trees was stored in the roots, which contained almost twice the amount of labelled N taken up 'late' than that absorbed 'early'. Nitrogen for spring growth was remobilised predominantly from the roots and accounted for some 43–49% of the labelled N recovered in the tree during winter. Results suggest that the nitrogen taken up 'late' in the season is preferentially stored in roots and used by peach trees to sustain new growth the following spring.
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  • 91
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    Plant and soil 212 (1999), S. 207-217 
    ISSN: 1573-5036
    Keywords: legume ; nitrogen ; N2-fixation ; pea ; sulphur
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract A S-deficient soil was used in pot experiments to investigate the effects of S addition on growth and N2-fixation in pea (Pisum sativum L.). Addition of 100 mg S pot−1 increased seed yield by more than 2-fold. Numbers of pods formed were the most sensitive yield component affected by S deficiency. Sulphur addition also increased the concentration of N in leaves and stems, and the total content of N in the shoots. The amounts of N fixed by pea were determined at four growth stages from stem elongation to maturity, using the 15N dilution technique. Sulphur addition doubled the amount of N fixed at all growth stages. In contrast, leaf chlorophyll content and shoot dry weight were increased significantly by S addition only after the flowering and pod fill stage, respectively. Pea roots were found to have high concentrations of S, reaching approximately 10 mg g−1 dry weight and being 2.6–4.4 times the S concentration in the shoots under S-sufficient conditions. These results suggest that roots/nodules of pea have a high demand for S, and that N2-fixation is very sensitive to S deficiency. The effects of S deficiency on pea growth were likely to be caused by the shortage of N, due to decreased N2-fixation.
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  • 92
    ISSN: 1573-5036
    Keywords: fire ; nitrogen ; phosphorus ; soil nutrient heterogeneity ; tree effects ; tropical dry forest
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Individual trees are known to influence soil chemical properties, creating spatial patterns that vary with distance from the stem. The influence of trees on soil chemical properties is commonly viewed as the agronomic basis for low-input agroforestry and shifting cultivation practices, and as an important source of spatial heterogeneity in forest soils. Few studies, however, have examined the persistence of the effects of trees on soil after the pathways responsible for the effects are removed. Here, we present evidence from a Mexican dry forest indicating that stem-related patterns of soil nutrients do persist following slash-and-burn removal of trees and two years of cropping. Pre-disturbance concentrations of resin extractable phosphorus (P), bicarbonate extractable P, NaOH extractable P, total P, total nitrogen (N) and carbon (C), KCl extractable nitrate (NO3 -), and net N mineralization and nitrification rates were higher in stem than dripline soils under two canopy dominant species of large-stemmed trees with contrasting morphologies and phenologies (Caesalpinia eriostachys Benth. and Forchhammeria pallida Liebm.). These stem effects persisted through slash burning and a first growing season for labile inorganic and organic P, NaOH inorganic P, and plant-available P, and through a second growing season for labile organic P, NaOH organic P, and plant-available P. While stem effects for extractable NO3 -, net nitrification rates, total N and C disappeared after felling and slash burning, these stem effects returned after the first growing season. These results support the view that tree-influenced patterns of soil nutrients do persist after tree death, and that trees contribute to the long-term spatial heterogeneity of forest soils.
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  • 93
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    Plant and soil 212 (1999), S. 173-181 
    ISSN: 1573-5036
    Keywords: nitrogen ; phosphatase activity ; phosphorus ; protease activity ; soil microbial biomass ; substrate-induced respiration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Estimating in situ N and P status of the soil microbiota is complicated because microbiological features reflect potentials rather than field conditions. Complementary microbiological assays were, therefore, combined to evaluate the N and P requirement of the microbiota in seven agricultural, grassland and forest topsoils of the Bornhöved Lake district as follows: (i) the sensitivity of the substrate-induced respiration (SIR) to supplemental addition of N and P was monitored during microbial growth and (ii) soil protease and phosphatase activities were analysed and related to soil mass and microbial biomass content. Nitrogen addition increased the maximal SIR rate in all except one soil indicating that the growth of organisms is restricted by this element when easily degradable C source is present. Supplemental N (and in some cases also P) retarded the respiratory response within the first 24 h which suggests microbial sensitivity and/or greater anabolic efficiency. With additional N the maximal SIR rate was most strongly enhanced in topsoils of the beech forest and the dystric alder forest. Thus, the microbial growth in these soils that were below litter horizons seems to be mostly restricted by N. Supplemental P positively affected respiratory response of soils under monoculture, wet grassland and dystric alder forest. In the dystric alder forest soil, high rates of alkaline and unbuffered phosphatase activity were observed when activity was related to either soil mass or microbial biomass content. The data of proteolytic and phospholytic enzymes are discussed with reference to nutrient deficiency and microbial strategy for N and P adsorption.
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  • 94
    ISSN: 1573-5036
    Keywords: effluent ; leaching ; 15N isotope ; nitrogen ; pasture ; uptake
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The objective of this study was to compare the N leaching loss and pasture N uptake from autumn-applied dairy shed effluent and ammonium fertilizer (NH4Cl) labeled with 15N, using intact soil lysimeters (80 cm diameter, 120 cm depth). The soil used was a sandy loam, and the pasture was a mixture of perennial ryegrass (Lolium perenne) and white clover (Trifolium repens). The DSE and NH4Cl were applied twice annually in autumn (May) and late spring (November), each at 200 kg N ha-1. The N applied in May 1996 was labeled with 15N. The lysimeters were either spray or flood irrigated during the summer. The autumn-applied DSE resulted in lower N leaching losses compared with NH4Cl. However, the N applied in the autumn had a higher potential for leaching than N applied in late spring. Between 4.5–8.1% of the 15N-labeled mineral N in the DSE and 15.1–18.8% of the 15N-labeled NH4Cl applied in the autumn were leached within a year of application. Of the annual N leaching losses in the DSE treatments (16.0–26.9 kg N ha-1), a fifth (20.3–22.9%) was from the mineral N fraction of the DSE applied in the autumn, with the remaining larger proportion from the organic fraction of the DSE, soil N and N applied in spring. In the NH4Cl treatments, more than half (53.8–64.8%) of the annual N leaching loss (55.9–57.6 kg N ha-1) was derived from the autumn-applied NH4Cl. DSE was as effective as NH4Cl in stimulating pasture production. Since only 4.4–4.5% of the annual herbage N uptake in the DSE treatment and 12.3–13.3% in the NH4Cl treatment were derived from the autumn-applied mineral N, large proportions of the annual herbage N uptake must have been derived from the N applied in spring, the organic N fraction in the DSE, soil N and N fixed by clover. The recoveries of 15N in the herbage were similar between the DSE and the NH4Cl treatments, but those in the leachate were over 50% less from the DSE than from the NH4Cl treatment. The lower leaching loss of 15N in the DSE treatment was attributed to the stimulated microbial activities and increased immobilization following the application of DSE.
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  • 95
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    Hydrobiologia 408-409 (1999), S. 375-387 
    ISSN: 1573-5117
    Keywords: eutrophication ; multi-lake studies ; phosphorus ; nitrogen ; chlorophyll-a ; transparency ; zooplankton ; macrophytes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Monitoring data obtained from 231 freshwater lakes and ponds in the Netherlands, covering the period 1980–1996, were used to analyse the relationships between (a) transparency and chlorophyll-a, and the effect of system characteristics on this relationship, (b) chlorophyll-aand nutrient concentrations, and the effect of biological variables and (c) nutrient concentrations and nutrient loading. (a) Chlorophyll-aimposes a maximum on water transparency, but deviations from this maximum can be large. Reducing chlorophyll-a, therefore, does not guarantee a sufficient improvement of transparency. Soil type and the average depth of a lake were shown to influence the relationship between chlorophyll-aand transparency. (b) The maximum ratios of both chlorophyll-a: total-P and chlorophyll-a: total-N were higher in systems dominated by filamentous cyanobacteria than in systems dominated by other algae, indicating the efficiency of the former group with respect to nutrients. In systems with an areal coverage with submersed macrophytes above 5%, concentrations of chlorophyll-aand nutrients were lower than in systems with lower coverages. The ratios between chlorophyll-aand nutrients were lower at coverages larger than 10%. This indicates both bottom-up and top-down control of algae by macrophytes. Grazing pressure by zooplankton was also found to lower the chlorophyll-a: nutrient ratios. (c) System specific linear relationships were found between the average concentrations of total-P and total-N in the incoming water and the summer mean concentration in the lake. This allows the assessment of admissible loads for individual lakes, with narrower confidence limits compared to traditional relationships based on combined data from many lakes. From the analysis, it is concluded that the chain of relationships from nutrient loading to transparency is complex, and depends on biological variables as well as system characteristics.
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  • 96
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    Biogeochemistry 44 (1999), S. 93-118 
    ISSN: 1573-515X
    Keywords: Everglades National Park ; mangrove soils ; organic matter ; nitrogen ; phosphorus ; sedimentation ; simulation model
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract The distribution and accumulation of organic matter, nitrogen (N) and phosphorus (P) in mangrove soils at four sites along the Shark River estuary of south Florida were investigated with empirical measures and a process-based model. The mangrove nutrient model (NUMAN) was developed from the SEMIDEC marsh organic matter model and parameterized with data from mangrove wetlands. The soil characteristics in the four mangrove sites varied greatly in both concentrations and profiles of soil carbon, N and P. Organic matter decreased from 82% in the upstream locations to 30% in the marine sites. Comparisons of simulated and observed results demonstrated that landscape gradients of soil characteristics along the estuary can be adequately modeled by accounting for plant production, litter decomposition and export, and allochthonous input of mineral sediments. Model sensitivity analyses suggest that root production has a more significant effect on soil composition than litter fall. Model simulations showed that the greatest change in organic matter, N, and P occurred from the soil surface to 5 cm depth. The rapid decomposition of labile organic matter was responsible for this decrease in organic matter. Simulated N mineralization rates decreased quickly with depth, which corresponded with the decrease of labile organic matter. The increase in organic matter content and decrease in soil bulk density from mangrove sites at downstream locations compared to those at upstream locations was controlled mainly by variation in allochthonous inputs of mineral matter at the mouth of the estuary, along with gradients in mangrove root production. Research on allochthonouns sediment input and in situ root production of mangroves is limited compared to their significance to understanding nutrient biogeochemistry of these wetlands. More accurate simulations of temporal patterns of nutrient characteristics with depth will depend on including the effects of disturbance such as hurricanes on sediment redistribution and biomass production.
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  • 97
    ISSN: 1573-515X
    Keywords: Chaohu Lake ; chemical fertilizer ; cycling ; denitrification ; multipond system ; nitrogen ; nutrient budget ; phosphorus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract During a two-year field study, an annual nutrient budget and cycles were developed for a small agricultural watershed. The study emphasized the integrated unit of the watershed in understanding the biogeochemistry. It was found that the total nutrient input was 39.1× 104 kg nitrogen and 3.91×104 kg phosphorus in the year 1995, of which the greatest input of nutrients to the watershed was chemical fertilizer application, reaching 34.7×104 kg (676 kg/ha) nitrogen and 3.88×104 kg (76 kg/ha) phosphorus. The total nutrient output from the watershed was 13.55×104 kg nitrogen and 0.40×104 kg phosphorus, while the largest output of nitrogen was denitrification, accounting for 44.1% of N output; the largest output of phosphorus was sale of crops, accounting for 99.4% of P output. The results show that the nutrient input is larger than output, demonstrating that there is nutrient surplus within the watershed, a surplus which may become a potential source of nonpoint pollution to area waters. The research showed that both denitrification and volatilization of nitrogen are key ways of nitrogen loss from the watershed. This suggests that careful management of fertilizer application will be important for the sustainable development of agriculture. The research demonstrated that a multipond system within the watershed had high retention rate for both water and nutrients, benefiting the water, nutrient and sediment recycling in the terrestrial ecosystem and helping to reduce agricultural nonpoint pollution at its source. Therefore, this unique watershed system should be recommended due to its great potential relevance for sustainable agricultural development.
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  • 98
    ISSN: 1573-515X
    Keywords: Chihuahuan desert ; desert ; desertification ; grassland ; nitrogen ; nutrient budgets ; phosphorus ; runoff
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract Rainfall simulation experiments were performed in areas of semiarid grassland (Bouteloua eriopoda) and arid shrubland (Larrea tridentata) in the Chihuahuan desert of New Mexico. The objective was to compare the runoff of nitrogen (N) and phosphorus (P) from these habitats to assess whether losses of soil nutrients are associated with the invasion of grasslands by shrubs. Runoff losses from grass- and shrub-dominated plots were similar, and much less than from bare plots located in the shrubland. Weighted average concentrations of total dissolved N compounds in runoff were greatest in the grassland (1.72 mg/1) and lowest in bare plots in the shrubland (0.55 mg/1). More than half of the N transported in runoff was carried in dissolved organic compounds. In grassland and shrub plots, the total N loss was highly correlated to the total volume of discharge. We estimate that the total annual loss of N in runoff is 0.25 kg/ha/yr in grasslands and 0.43 kg/ha/yr in shrublands — consistent with the depletion of soil N during desertification of these habitats. Losses of P from both habitats were very small.
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  • 99
    ISSN: 1573-5117
    Keywords: nitrogen ; phosphorus ; pore water ; macrophyte ; floodplain ; Paraná River
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Inorganic nitrogen and soluble reactive phosphate (o-P) concentrations were measured in the water of a marsh and in its interstitial water at two sites, and in the river water of a floodplain marsh of the Lower Paraná River. These values were compared with the N and P concentration in sediments and macrophyte biomass in order to assess nutrient availability, fate and storage capacity. High variability was found in the interstitital water using a 1 cm resolution device. Nitrate was never detected in the pore water. Depth averaged NH4 + concentrations in the upper 30 cm layer often ranged from N = 1.5 to 1.8 mg l-1, but showed a pronounced minimum (0.5–0.7 mg l-1), close to (March 95), or relatively soon after (May 94) the end of the macrophyte growing season. Soluble phosphate showed a large variation between P = 0.1–1.1 mg l-1 without any discernible seasonal pattern. NH4 + depletion in the pore water concentration and low N/P ratios (3.7 by weight) within the macrophyte biomass at the end of the growing period suggest that available N limits plant growth. NH4 + and o-P concentrations were 35 and 7 times higher, respectively, in the pore water than in the overlying marsh, suggesting a permanent flux of nutrients from the sediments. o-P accumulate in the marsh leading to higher concentrations than in the incoming river. NH4 + did not accumulate in the marsh, and no significant differences were observed between the river and the marsh water, while the NO3 - contributed by the river water was depleted within the marsh, caused probably by coupled nitrification-denitrification at the sediment–water interface. Although an order of magnitude smaller, the pore water pool can supply enough nutrients to build up the macrophyte biomass pool, but only if a fast turnover is attained. The Paraná floodplain marsh retains a large amount of nutrients being stored mainly in the sediment compartment.
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  • 100
    ISSN: 1573-5117
    Keywords: shallow lake ; nutrient loading ; retention ; nitrogen ; phosphorus ; release
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The shallow (mean depth 4.9 m), polymictic and eutrophic lake Müggelsee was highly loaded with phosphorus (6 gP m-2a-1) and nitrogen (170 gN m-2a-1) by the river Spree up to the end of the 1980s. Annual load declined by 40–50% during the last years (1991–97). Phosphorus retention fluctuated strongly during the seasonal cycle between −200 and +100 kgP d-1and from year to year between −44% and + 26% of the P import. At the end of the eighties, the P retention capacity of the sediment was exceeded and Müggelsee became a source of phosphorus. The lake regained its ability to retain P in the sediments after external load reduction in the 1990s. However, the internal load of P reached the level of the external one. The release of P during summer was strongly related to the import of nitrate. On long-term average (1979–1997), less than 1% of the P input was retained in Müggelsee. About 24% of the nitrogen load were removed in the lake on annual mean. This rate decreased during the last years.
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