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  • Chemistry  (15)
  • Life and Medical Sciences  (5)
  • Drosophila melanogaster  (2)
  • Mexico  (2)
  • Aircraft Propulsion and Power
  • Cell & Developmental Biology
  • Fundamental concepts
  • Philippinen
  • 1995-1999  (24)
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  • 1
    ISSN: 1617-4623
    Keywords: Cytochrome P450 genes ; Drosophila melanogaster ; Gene clusters ; Multigene family ; Insecticide resistance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Twelve cytochrome P450 cDNA fragments were cloned fromDrosophila melanogaster by reverse transcriptase/PCR (RT/PCR) using degenerate oligonucleotide primers. The corresponding genes belong to several subfamilies of the CYP4 and CYP9 P450 families. Only two of these genes,Cyp4d1 andCyp4d2, have previously been described.In situ hybridization of each of the cDNA fragments showed two clusters of genes; one near the tip of theX chromosome and the other on the left arm of chromosome2. Interestingly the latter cluster comprises widely divergent genes belonging both to the CYP9 and CYP4 families and also to the CYP6 family (Cyp6a2). Putative allelic variants of several of the genes were found in different insecticide-resistant and -susceptible strains (Hikone R, Haag 79 and Oregon R). The identification of these genes and alleles will allow us to clarify the involvement of P450s in xenobiotic metabolism and will facilitate a genetic analysis of P450 functions in insects.
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  • 2
    ISSN: 1617-4623
    Keywords: Key words Cytochrome P450 genes ; Drosophila melanogaster ; Gene clusters ; Multigene family ; Insecticide resistance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  Twelve cytochrome P450 cDNA fragments were cloned from Drosophila melanogaster by reverse transcriptase/PCR (RT/PCR) using degenerate oligonucleotide primers. The corresponding genes belong to several subfamilies of the CYP4 and CYP9 P450 families. Only two of these genes, Cyp4d1 and Cyp4d2, have previously been described. In situ hybridization of each of the cDNA fragments showed two clusters of genes; one near the tip of the X chromosome and the other on the left arm of chromosome 2. Interestingly the latter cluster comprises widely divergent genes belonging both to the CYP9 and CYP4 families and also to the CYP6 family (Cyp6a2). Putative allelic variants of several of the genes were found in different insecticide-resistant and -susceptible strains (Hikone R, Haag 79 and Oregon R). The identification of these genes and alleles will allow us to clarify the involvement of P450s in xenobiotic metabolism and will facilitate a genetic analysis of P450 functions in insects.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Hydrobiologia 381 (1998), S. 1-7 
    ISSN: 1573-5117
    Keywords: Tropical limnology ; meromixis ; nutrients ; plankton ; Nayarit ; Mexico ; Isabela island
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The Isabela Crater-Lake is a bright-green, hypersaline lake (68–112.5 mS cm-1) on Isabela Island off the Pacific coast of Nayarit, Mexico. Some salient features were documented in November 1993. It appears meromictic, with three well-defined strata separated by sharp pycnoclines. Surface water was warm (32 °C) reaching a subsurface (0.5–1 m) maximum temperature (33 °C), declining gradually to 26.7 °C at maximum depth (17.5 m). Dissolved oxygen was near saturation at the surface, attained 145 percent saturation at 0.5 m, but was completely absent by 2.5 m. Eh was maximum at the surface (123 mV), declining to a minimum at 3 m (–261 mV), and was about –240 mV from 3.5 m to the bottom. The pH varied from 9.3 in surface waters to slightly acid (6.4) in deep anoxic layers. Atypically, NO3 was more abundant than NH4 in both aerobic and anaerobic strata. PO4 and SiO2 concentrations were extremely high. The planktonic microbial community was formed by four groups: bacteria (photosynthetic sulfur bacteria and heterotrophic bacteria), phytoflagellates (mainly cryptomonads), heterotrophic nanoflagellates ( Spumella spp., Bodo spp.) and ciliates (Hypotricha and Oligotricha). Bacteria occurred throughout the water column, but other biota were restricted to surface waters.
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  • 4
    ISSN: 1573-5117
    Keywords: aufwuchs ; polyurethane foam units ; colonization ; saline lakes ; crater lakes ; Mexico
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Littoral protozoan assemblages from two hyposaline crater-lakes (Lakes Alchichica and Atexcac) located in the Oriental Valley, center of Mexico, were studied using the polyurethane foam units (PFU) colonization method. Fifteen PFU (5 dates, three replicates per date, 64 × 72 × 50 mm) were located in the littoral area of each lake and collected at 8, 14, 20–21, 28–29 and 38–39 d intervals. Both lakes were hyposaline (Salinity between 6 and 7.1 g l-1) and alkaline (pH range: 8.4–9.1). Eighty seven species were observed in both lakes. In Alchichica 44 species and 43 in Atexcac. Ciliates and flagellates species dominated the assemblages' composition. The flagellates Bodo caudatus and Spumella termo and the ciliate Cyclidium glaucoma were the most abundant species in Alchichica, while in Atexcac the flagellates Cryptomonas ovata and B. caudatus and the ciliates C. glaucoma and Stylonychia notophora were most abundant. Except for S. notophora, which consumes algae, the other species are mainly bactivores.
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  • 5
    Electronic Resource
    Electronic Resource
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 34 (1996), S. 1219-1227 
    ISSN: 0887-624X
    Keywords: 1,2,4-benzenetricarboxylic acid monoesters ; poly(amide-imide) structural regularity ; poly(amide-imide) “one-pot” synthesis ; 13C-NMR spectra of poly(amide-imide) ; phosphorylation reaction ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Aromatic processable poly(amide-imide)s have been prepared according to the Yamazaki and Higashi phosphorylation reaction from flexible aromatic diamines and a mixture of isomeric 1,2,4-benzenetricarboxylic acid monoethylesters following a novel “one-pot” procedure. The polymerization was performed in 1-methyl-2-pyrrolidone/LiCl solutions using triphenylphosphite and pyridine as condensing agents to form amide bonds. Cyclization of the intermediate poly(amide-amic ethylester) occurred by eliminating ethanol under the polymerization conditions used, thus leading to the formation of imide rings. The influence of several parameters which regulate the degree of polymerization and the formation of the imide rings, such as reaction temperature, triphenylphosphite/monomers molar ratio, and pyridine concentration was carefully investigated. In particular, the catalytic activity of pyridine in the imidization reaction has been demonstrated. 13C-NMR spectroscopy has been used to show the absence of constitutional regularity in the prepared PAIs thus indicating equal reactivity toward polycondensation of the two different carboxyl groups of the 1,2,4-benzenetricarboxylic acid monoethylesters. © 1996 John Wiley & Sons, Inc.
    Additional Material: 8 Ill.
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  • 6
    ISSN: 0935-9648
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Additional Material: 4 Ill.
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  • 7
    ISSN: 0935-9648
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Additional Material: 5 Ill.
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  • 8
    ISSN: 0899-0042
    Keywords: Circular dichroism ; helicity rule ; X-ray structure determination ; ultraviolet spectra ; n - π* and π - π* bands ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Chiroptical properties of a series of 3 and/or 4-heterosubstituted 2(5H)-furanones were investigated with respect to correlation with absolute configuration. The n - π* and π - π* Cotton effects have been assigned on the basis of comparison with the UV spectra in solvents of varying polarity. It is demonstrated that the n - π* transition in 4-amino substituted 2(5H)-furanones appears at shorter wavelength with respect to the π - π* transition. With the exception of 4-pyrrolidino and 4-benzylamino substituted 2(5H)-furanones, other heterosubstituted 2(5H)-furanones follow the butenolide configurational rule (Gawronski et al. J. Org. Chem. 61:1513-1515, 1996). Absolute configuration of 2(5H)-furanone derivatives can also be assigned according to the sign of the Cotton effect (of unknown origin) at 200-230 nm. The structure of four representative sulfur and nitrogen substituted 2(5H)-furanones has been analyzed by X-ray diffraction. The results indicate planarity of the furanone ring and extended conjugation in 4-amino substituted 2(5H)-furanones. Chirality 9:537-544, 1997. © 1997 Wiley-Liss, Inc.
    Additional Material: 4 Ill.
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  • 9
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Die Kinetik der Vulkanisation sowie die Vernetzungsdichte von Styrol-Butadien-Kautschukmischungen wurden mit zwei Vulkanisationssystemen, einem wirksamen (EV) und einem konventionellen (CV), untersucht. Ein oberflächenmodifiziertes Silikat mit Boramingruppen (Si—O—B—(NH2)2) wurde als Füllstoff eingesetzt. Unbehandeltes und mit zwei Silanen (γ-Mercaptopropyl-trimethoxysilan und γ-Aminopropyl-triethoxysilan) modifiziertes Silikat wurden zum Vergleich eingesetzt. Die bestenkinetischen Parameter, wie die höchste Vulkanisierungsgeschwindigkeit, die längste Induktionszeit und die kleinste Aktivierungsenergie, wurden für die Mischung mit boraminiertem Silikat erhalten. Die Vernetzungsdichte, die mit dieser Mischung erreicht wurde, ist ähnlich der von mit Silan modifiziertem Silikat erzielten, da wahrscheinlich die Boramingruppen auf der Silikatoberfläche besser verteilt sind. Diese Fakten führen zu wichtigen technologischen Verbesserungen: größere Verarbeitungssicherheit, schnellere Vulkanisierungsgeschwindigkeit und verbesserte physikalische Eigenschaften.
    Notes: Vulcanization kinetics and crosslink density of styrene-butadiene rubber compounds have been studied with two vulcanization systems, an efficient (EV) and a conventional (CV) one. A surface-modified silica with boron-amine groups (Si—O—B—(NH2)2) was employed as filler. Untreated and modified silica with two silanes (γ-mercaptopropyl-trimethoxysilane and γ-aminopropyl-triethoxysilane) have been used as reference.The best kinetic parameters, such as highest vulcanization rate, longest induction time and lowest activation energy, were obtained for the compound with boronaminated silica. The crosslink density, achieved with this compound, is similar to that with silane-modified silica, probably because of the better surface distribution of boron-amine groups on the silica. These facts lead to important technological improvements: better processing safety, faster vulcanization rate and improved physical properties.
    Additional Material: 4 Ill.
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  • 10
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Bioluminescence and Chemiluminescence 13 (1998), S. 371-378 
    ISSN: 0884-3996
    Keywords: bioluminescence ; luciferase ; ATP ; immobilization ; glass ; poly-L-lysine ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: The bioluminescent reaction catalysed by firefly luciferase has become widely established as an outstanding analytical system for assay of ATP. When used in solution, luciferase is unstable and cannot be re-used, a problem that can be partially circumvented by immobilizing the enzyme on solid substrates. Transparent glass is especially advantageous over alternative immobilizing matrices, since it allows most of the emitted photons to be detected. We report a new method for luciferase immobilization on glass which does not require prior silanization and glutaraldehyde activation, thus saving preparation time and minimizing enzyme inactivation. Our method is based on the co-immobilization by adsorption of luciferase (from a firefly lantern extract) and poly-L-lysine (PL) on non-porous glass strips. Luciferase immobilized in this way exhibits minimal variations in intersample activity, high sensitivity for ATP detection (linear luminescence responses down to 50 nmol/L) and good stability (full activity for at least 60 days when stored at -80°C). PL-mediated immobilization of luciferase on glass strips provides an attractive strategy for the design of specific ATP biosensors, with potential in industry, environmental screening, medicine and biological research. © 1998 John Wiley & Sons, Ltd.
    Additional Material: 3 Ill.
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