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  • 1
    Electronic Resource
    Electronic Resource
    Hamiltonian approach to the magnetostatic equilibrium problem (1995)
    [S.l.] : American Institute of Physics (AIP)
    Physics of Plasmas 2 (1995), S. 4499-4512 
    Details
    ISSN: 1089-7674
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The purpose of this paper is to investigate the classical scalar-pressure magnetostatic equilibrium problem for nonsymmetric configurations in the framework of a Hamiltonian approach. Requiring that the equilibrium admits locally a family of nested toroidal magnetic surfaces, the Hamiltonian equations describing the magnetic flux lines in such a subdomain are obtained for a general canonical curvilinear coordinate system. The properties of such a coordinate system are investigated and a representation of the magnetic field is obtained. Its basic feature is that the magnetic field must fulfill suitable periodicity constraints to be imposed on arbitrary rational magnetic surfaces for general nonsymmetric toroidal equilibria, i.e., it is quasisymmetric. Implications for the existence of magnetostatic equilibria are pointed out. In particular, it is proven that a generalized equilibrium equation exists for such quasisymmetric equilibria, which extends the Grad–Shafranov equation to fully three-dimensional configurations. As an application, a representation is obtained for generalized helically symmetric equilibrium, extending the definition given by Nührenberg and Zille [Phys. Lett. A 129, 113 (1988)]. Since the new representation overcomes the inconsistency exhibited by the previous representation near the magnetic axis, pointed out by Garren and Boozer [Phys. Fluids B 3, 2805, 2822 (1991)], it appears potentially useful to interpret the numerical findings of quasihelical equilibria obtained so far. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.871008
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  • 2
    Electronic Resource
    Electronic Resource
    Distinct structural features of the .alpha. and .beta. subunits of nitrogenase molybdenum-iron protein of Clostridium pasteurianum: an analysis of amino acid sequences (1988)
    s.l. : American Chemical Society
    Biochemistry 27 (1988), S. 2800-2810 
    Details
    ISSN: 1520-4995
    Source: ACS Legacy Archives
    Topics: Biology , Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/bi00408a021
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  • 3
    Electronic Resource
    Electronic Resource
    Production of Biologically Active Human Protein C in the Milk of Transgenic Mice (1992)
    Oxford, UK : Blackwell Publishing Ltd
    Annals of the New York Academy of Sciences 665 (1992), S. 0 
    Details
    ISSN: 1749-6632
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Natural Sciences in General
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1749-6632.1992.tb42602.x
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  • 4
    Electronic Resource
    Electronic Resource
    The Porcine Mammary Gland as a Bioreactor for Complex Proteinsa (1994)
    Oxford, UK : Blackwell Publishing Ltd
    Annals of the New York Academy of Sciences 721 (1994), S. 0 
    Details
    ISSN: 1749-6632
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Natural Sciences in General
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1749-6632.1994.tb47394.x
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  • 5
    Electronic Resource
    Electronic Resource
    The recent evolutionary origin of the phenylalanine-sensitive isozyme of 3-deoxy-d-arabino-heptulosonate 7-phosphate synthase in the enteric lineage of bacteria (1987)
    Springer
    Journal of molecular evolution 25 (1987), S. 159-167 
    Details
    ISSN: 1432-1432
    Keywords: Metabolic evolution ; Aromatic biosynthesis ; Regulatory isozymes ; Enteric bacteria
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Evolutionary events that generated the three regulatory isozymes of 3-deoxy-d-arabino-heptulosonate 7-phosphate (DAHP) synthase present in contemporary strains ofEscherichia coli have been proposed recently [Ahmad et al. (1986) J Bacteriol 165:146–154]. The phylogenetic subdivision of gram-negative prokaryotes studied (Superfamily B) includes enteric bacteria, anOceanospirillum cluster, pseudomonad Group I (e.g.,Pseudomonas aeruginosa), pseudomonad Group V (e.g.,Xanthomonas), and theAcinetobacter grouping. DAHP synthase-phe, a regulatory isozyme subject to allosteric control byl-phenylalanine, was the last member of the isozyme family to evolve. Thus, DAHP synthase-phe is absent throughout Superfamily B except within the enteric lineage. Bacteria that make up the enteric lineage (Escherichia, Klebsiella, Erwinia, Serratia, Proteus, Aeromonas, andAlteromonas) were examined in detail; DAHP synthasephe was present in each of these organisms. Therefore, the isozyme originated between the separation of the enteric andOceanospirillum lineages, prior to the divergence ofAlteromonas putrefaciens (44% homology withE. coli by DNA:rRNA hybridization) from the rest of the enteric lineage. DAHP synthase-tyr and DAHP synthase-trp were uniformly present within the enteric lineage, although it was often necessary to derepress DAHP synthase-trp by physiological manipulation in order to demonstrate its presence.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02101758
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  • 6
    Electronic Resource
    Electronic Resource
    The evolutionary pattern of aromatic amino acid biosynthesis and the emerging phylogeny of pseudomonad bacteria (1983)
    Springer
    Journal of molecular evolution 19 (1983), S. 272-282 
    Details
    ISSN: 1432-1432
    Keywords: Microbial phylogeny ; Evolution ; Aromatic biosynthesis ; Regulatory enzymes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Pseudomonad bacterial are a phylogenetically diverse assemblage of species named within contemporary genera that includePseudomonas, Xanthomonas andAlcaligenes. Thus far, five distinct rRNA homology groups (Groups I through V) have been established by oligonucleotide cataloging and by rRNA/DNA hybridization. A pattern of enzymic features of aromatic amino acid biosynthesis (enzymological patterning) is conserved at the level of rRNA homology, five distinct and unambiguous patterns therefore existing in correspondence with the rRNA homology groups. We sorted 87 pseudomonad strains into Groups (and Subgroups) by aromatic pathway patterning. The reliability of this methodology was tested in a blind study using coded cultures of diverse pseudomonad organisms provided by American Type Culture Collection. Fourteen of 14 correct assignments were made at the Group level (the level of rRNA homology), and 12 of 14 correct assignments were made at the finer-tuned Subgroup levels. Many strains of unknown rRNA-homology affiliation had been placed into tentative rRNA groupings based upon enzymological patterning. Positive confirmation of such strains as members of the predicted rRNA homology groups was demonstrated by DNA/rRNA hybridization in nearly every case. It seems clear that the combination of these molecular approaches will make it feasible to deduce the evolution of biochemical-pathway construction and regulation in parallel with the emerging phylogenies of microbes housing these pathways.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02099974
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  • 7
    Electronic Resource
    Electronic Resource
    Phenylalanine hydroxylase and isozymes of 3-deoxy-D-arabino-heptulosonate 7-phosphate synthase in relationship to the phylogenetic position of Pseudomonas acidovorans (Ps. sp. ATCC 11299a) (1985)
    Springer
    Archives of microbiology 141 (1985), S. 32-39 
    Details
    ISSN: 1432-072X
    Keywords: Phylogeny ; Pseudomonads ; Aromatic biosynthesis ; DAHP synthase ; Phenylalanine hydroxylase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The evolution of aromatic amino acid biosynthesis and its regulation is under study in a large assemblage of prokaryotes (Superfamily A) whose phylogenetic arrangement has been constructed on the criterion of oligonucleotide cataloging. One section of this Superfamily consists of a well defined (rRNA homology) cluster denoted as Group III pseudomonads. Pseudomonas acidovorans ATCC 11299a, a Group III member, was chosen for indepth studies of 3-deoxy-d-arabino-heptulosonate 7-phosphate (DAHP) synthase, the initial regulatory enzyme of aromatic biosynthesis. This strain is of particular interest for evolutionary studies of aromatic metabolism because it possesses phenylalanine hydroxylase, an enzyme whose physiological role and distribution among prokaryotes is largely unknown. Although P. acidovorans ATCC 11299a has been of uncertain identity, we now establish it unambiguously as a species of acidovorans by virtue of its 87% DNA homology with P. acidovorans ATCC 15668 (type strain). This result conformed with enzyme patterning studies which placed ATCC 11299a into pseudomonad Group IIIa, a subgroup containing the acidovorans species. Crude extracts of Group III pseudomonads had previously been shown to share, as a common group characteristic, sensitivity of DAHP synthase to feedback inhibition by either l-tyrosine or l-phenylalanine. Detailed studies with partially purified preparations from strain ATCC 11299a revealed the presence of two distinct regulatory isozymes, DAHP synthase-phe and DAHP synthase-tyr. DAHP synthase-tyr is tightly controlled by l-tyrosine with 50% inhibition of activity being achieved at 4.0 μM effector. DAHP synthase-phe is inhibited 50% by 40 μM l-phenylalanine and exhibits dramatic changes in levels of activity, as well as chromatographic elution patterns, in response to dithiothreitol. This two-isozyme pattern of DAHP synthase has not been described previously, although it may prove to be widespread.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00446736
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  • 8
    Electronic Resource
    Electronic Resource
    Transgenesis in mice by cytoplasmic injection of polylysine/DNA mixtures (1995)
    Springer
    Transgenic research 4 (1995), S. 353-360 
    Details
    ISSN: 1573-9368
    Keywords: microinjection ; transgenesis ; polylysine ; DNA
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Pronuclear injection is currently the most often used method to make transgenic animals, but in some animal species it is temporally restrictive due to difficulty in visualizing pronuclei. However, the injection of construct DNA into the cytoplasm does not result in transgenesis. The production of transgenic mice by a cytoplasmic microinjection technique of polylysine complexed DNA into pronuclear stage zygotes is described. Transgenic mice were produced from cytoplasmic microinjection of mixtures of a 5.3 kb linearized DNA and poly-l-lysine (degree of polymerization=51). Effects on transgenic frequency of both the lysine to phosphate ratio of polylysine to DNA and DNA concentration were studied. About 12.8% of the pups born from zygotes cytoplasmically microinjected with a polylysine/DNA mixture having a lysine to phosphate ratio (L:P) of 1∶1 microinjection positive control of DNA alone was 21.7%. No transgenic pups were born from microinjection of DNA alone into the cytoplasm. Complexes of polylysine/DNA were detected using agarose gel electrophoresis at the conditions which produced transgenic mice. The presence of polylysine with construct DNA altered thein vitro activities of restriction endonuclease and DNA ligase on the construct DNA. The production of transgenic animals using DNA and polylysine in the absence of any other signal protein suggests that a DNA/polylysine complex but not DNA alone can act as a substrate for transgenesis from the cytoplasm.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01973753
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  • 9
    Electronic Resource
    Electronic Resource
    Influence of time of gene microinjection on development and DNA detection frequency in bovine embryos (1994)
    Springer
    Transgenic research 3 (1994), S. 226-231 
    Details
    ISSN: 1573-9368
    Keywords: DNA integration ; transgenics ; micromanipulation ; PCR
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The effect of DNA microinjection at various times afterin vitro insemination on DNA detection and survival rates of bovine embryos was investigated. Oocytes were inseminated 24 h after maturation with frozen/thawed semen prepared with a Percoll separation procedure. At 11, 15 and 19 h after insemination, embryos were centrifuged to visualize pronuclei and microinjected with a murine whey acidic protein-human protein C genomic DNA construct. After culture for 7 days on Buffalo Rat Liver cells, embryos were assessed for stage of development and assayed for the presence of the transgene by polymerase chain reaction. Of zygotes in the 11h after insemination treatment, 16% (25/152) of non-injected and 7% (11/161) of injected embryos developed to the morula or blastocyst stage. Comparable development of non-injected and injected embryos treated at 15h after insemination was 15% (23/158) and 4% (6/159) and treated at 19 h after insemination was 14% (23/162) and 1% (1/165), respectively. Development of injected embryos was greater (p〈0.05) when injection was performed at 11 h after insemination compared to 19 h after insemination. Development of non-injected embryos was greater (p〈0.01) than that of injected embryos. There was no difference in transgene detection frequency in embryos of all developmental states between treatments (53% at 11; 50% at 15; 48% at 19h after insemination). Injected embryos testing positive for the presence of the transgene exhibited increased development over negative embryos (p〈0.01). Greater development efficiencies can be obtained in microinjected bovine embryos when injection is performed early in pronuclear formation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02336775
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  • 10
    Electronic Resource
    Electronic Resource
    Altered IL-1 Expression and Compartmentalization in Monocytes from Patients with AIDS Stimulated with Mycobacterium avium Complex (1997)
    Springer
    Journal of clinical immunology 17 (1997), S. 387-395 
    Details
    ISSN: 1573-2592
    Keywords: Mycobacterium avium (MA) ; MA complex ; AIDS ; cytokines ; interleukin-1 (IL-1) ; IL-6 ; monocytes ; tumor necrosis factor-α
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The pathophysiologic basis for the exuberant intracellular growth of Mycobacterium avium complex (MAC) in AIDS patients is unclear but may relate to altered expression of modulatory cytokines. Interleukin (IL)-1, IL-6, and TNF-α expression by monocytes from AIDS patients and healthy subjects (HS) stimulated with isogeneic MAC strains (SmT, smooth-transparent, virulent; SmD, smooth-domed, avirulent) was examined. Spontaneous cytokine production was not observed in patients with AIDS. MAC strains induced less IL-1α and IL-1β release in AIDS patients than HS (P 〈 0.05). The ratio of cell-associated to supernatant IL-1α also was increased in AIDS patients (P = 0.03). IL-1β mRNA expression paralleled protein release in either group of subjects. In both HS and AIDS patients, stimulation with SmD induced more IL-1 and TNF-α release by monocytes compared to SmT. In AIDS patients, SmD also induced greater IL-6 release than SmT (P 〈 0.01). Alterations in monocyte expression and compartmentalization of the regulatory cytokines IL-1 and IL-6 may enhance bacterial replication and contribute to the patho-genesis of MAC infection in AIDS.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1027316324382
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