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  • 1
    Electronic Resource
    Electronic Resource
    Release of glucosylglycerol from the cyanobacterium Synechocystis spec. SAG 92.79 by hypoosmotic shock (1990)
    Springer
    Archives of microbiology 153 (1990), S. 405-408 
    Details
    ISSN: 1432-072X
    Keywords: Cyanobacteria ; Exudation ; Salt stress ; Glucosylglycerol ; Synechocystis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract When cells of Synechocystis, adapted to 684 mmol/l NaCl, were exposed to hypoosmotic shock by reducing NaCl concentration to more than 250 mmol/l, significant amounts of organic material were liberated which could be increased by increasing shock strength. After maximal hypoosmotic shock (684 mmol/l→ 2 mmol/l NaCl) 40–50% of photosynthetically labelled organic material occurred in the surrounding medium. The main compound exudates was the osmoprotective compound glucosylglycerol. Minor exudates were amino acids, organic acids and carbohydrates. In contrast a hyperosmotic shock (2 mmol/l→684 mmol/l NaCl) liberated only one fourth of the amount liberated by a hypoosmotic shock.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00249013
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  • 2
    Electronic Resource
    Electronic Resource
    Comparison of salt- and heat-induced alterations of protein synthesis in the cyanobacterium Synechocystis sp. PCC 6803 (1991)
    Springer
    Archives of microbiology 155 (1991), S. 587-592 
    Details
    ISSN: 1432-072X
    Keywords: Cyanobacteria ; Salt shock ; Heat shock ; Protein synthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Protein synthesis of the cyanobacterium Synechocystis spec. PCC 6803 decreases after a 684 mM NaCl salt shock. Qualitative changes were observed during the shock and the subsequent adaptation process using one-dimensional polyacrylamide electrophoresis. Proteins of apparent molecular masses of 13.0, 14.2, 16.6, 20.0, 21.0, 23.0, 33.0, 47.0, 52.0, 65.0 and 72.0 kDa are synthesized at enhanced rates after salt stress. The proteins of 14.2, 21.1 and 52.0 kDa are transiently induced during the first hours of the adaptation phase, while the other proteins are also synthesized at enhanced rates in salt-adapted cells. The proteins of 14.2, 23.0, 33.0 and 65.0 kDa are also induced by heat shock (43°C). Heat shock proteins of about 88.0, 75.0, 58.0, 17.5 and 13.8 kDa, in contrast, are induced by heat shock but not by salt. Two-dimensional polyacrylamide electrophoresis showed that the induced salt and heat shock proteins in some cases consisted of isoforms of different isoelectric points.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00245354
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  • 3
    Electronic Resource
    Electronic Resource
    Selection and characterization of mutants of the cyanobacterium Synechocystis sp. PCC 6803 unable to tolerate high salt concentrations (1992)
    Springer
    Archives of microbiology 158 (1992), S. 429-434 
    Details
    ISSN: 1432-072X
    Keywords: Cyanobacteria ; Glucosylglycerol ; Random cartridge mutagenesis ; Salt tolerance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Three mutants of the cyanobacterium Synechocystis sp. PCC 6803 unable to tolerate high salt concentrations were generated using random cartridge mutagenesis. Analysis of the phenotypes revealed that the salt sensitivity of one mutant (6803/143) is caused by a block in the synthesis of the osmoprotective substance glucosylglycerol, while in the two other mutants no physiological defect could be detected which was responsible for the loss of salt tolerance. Southern hybridization analyses and cloning of the integration sites of the resistance marker demonstrated that different genes are affected in each of the three mutants.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00276304
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  • 4
    Electronic Resource
    Electronic Resource
    Synthesis of glucosylglycerol in salt-stressed cells of the cyanobacterium Microcystis firma (1987)
    Springer
    Archives of microbiology 148 (1987), S. 275-279 
    Details
    ISSN: 1432-072X
    Keywords: Cyanobacteria ; Microcystis ; Glucosylglycerol ; Salt adaptation ; Synthesis rate ; Turnover
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The unicellular cyanobacterium Microcystis furma tolerates salinity by accumulating the osmoprotective compound glucosylglycerol. After salt shock, the initial rate of glucosylglycerol synthesis is independent of the NaCl concentration used. In pulse chase experiments with NaH14CO3, synthesis of glucosylglycerol by salt-adapted cells was found to be rapid, whereas no sign of its breakdown was detected. Therefore, it is concluded that no turnover of glucosylglycerol takes place in salt-adapted cells. The specific capacity of the glucosylglycerol-forming enzyme system may be one reason for the salt resistance limit.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00456704
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  • 5
    Electronic Resource
    Electronic Resource
    Identification of salt-regulated genes in the genome of the cyanobacterium Synechocystis sp. strain PCC 6803 by subtractive RNA hybridization (1999)
    Springer
    Archives of microbiology 172 (1999), S. 377-386 
    Details
    ISSN: 1432-072X
    Keywords: Key words Chaperone ; Cyanobacteria ; groEL ; isiA ; RNA helicase ; Salt stress ; Subtractive RNA ¶hybridization ; Synechocystis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract To identify genes transcribed preferentially under salt stress, a subtractive RNA hybridization procedure was applied to the cyanobacterium Synechocystis sp. PCC 6803. The screening of a genomic library led to the identification of several RNA species that were more abundant in salt-stressed cells than in control cells. Salt-dependent transcription of the identified genes was verified in Northern blot experiments. In addition to the previously characterized genes cpn60 (encoding GroEL; a molecular chaperone) and isiA (encoding a chlorophyll-binding protein), genes encoding a protein of unknown function (slr0082) and a putative RNA helicase (slr0083) were identified as salt-regulated genes in Synechocystis. Genes slr0082 and slr0083, located at sites adjacent to each other on the Synechocystis chromosome, were transcribed from separate promoters and showed the most significant induction 1–3 h after salt shock. The salt-regulated promoters of these two genes were mapped. Genes cpn60, slr0082, and slr0083 were also found to be induced by a cold shock. The possible role of the identified gene products for salt adaptation of Synechocystis is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002030050774
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  • 6
    Electronic Resource
    Electronic Resource
    Polytrifluormethylstyrole, eine polymerklasse mit aussergewöhnlichen optischen eigenschaftenVortrag anläßlich der Tagung der Fachgruppe “Makromolekulare Chemie” der Gesellschaft Deutscher Chemiker über “Synthetische Polymere mit außergewöhnlichen Eigenschaften” in Bad Nauheim am 19. und 20. April 1982Herrn Prof. Dr. Otto Bayer in memoriam gewidmet (1982)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 109 (1982), S. 285-293 
    Details
    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: Homopolymers of 2-, 3- and 4-trifluoromethylstyrene, 4-perfluoroisopropylstyrene, 3,5-bis-trifluoromethyl-styrene and a 1 : 1 copolymer of 2,4- and 2,5-bis-trifluoromethyl-styrene have been synthesized and the refractive indices nD, Abbe-numbers νD and glass transition temperatures of the polymers have been determined.With regard to optical applications poly-2-trifluoromethyl-styrene is particularly interesting since its optical properties are in a region of the n-ν-diagram that has not been reached by thermoplastic polymers or inorganic glasses before.The most important mechanical and thermal properties of this polymer are reported. Reactivity ratios of the binary copolymerisation of 2-trifluoromethyl-styrene with styrene, methyl-methacrylate and n-butyl-acrylate are listed as well as optical data and glass transition temperatures of some copolymers of 2-trifluoromethyl-styrene.
    Notes: Homopolymerisate aus 2-, 3- und 4-Trifluormethylstyrol, 4-Perfluorisopropylstyrol, 3,5-Bis-trifluormethylstyrol und ein 1 : 1 Copolymerisat aus 2,4- und 2,5-Bis-trifluormethylstyrol wurden hergestellt und Brechungsindices, Abbe-Zahlen sowie Glasübergangstemperaturen der Polymerisate bestimmt.Von diesen Thermoplasten ist das Poly-2-trifluormethylstyrol im Hinblick auf optische Anwendungen besonders interessant, da es in einem weder von anorganischen Gläsern noch von bekannten thermoplastischen Kunststoffen bisher erreichten Gebiet des n-v-Diagrammes liegt.Die wichtigsten mechanischen und thermischen Eigenschaften dieses Polymeren und die Copolymerisationsparameter für die binäre Copolymerisation von 2-Trifluormethylstyrol mit Styrol, Methylmethacrylat und n-Butylacrylat wurden bestimmt. Optische Daten und Glastemperaturen einiger Copolymerisate des 2-Trifluormethylstyrols werden mitgeteilt.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1982.051090119
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  • 7
    Electronic Resource
    Electronic Resource
    [2π + 2π]-Photocycloadditionen in Tricyclo[3.2.2.02,4]nonadien-Derivaten. Synthese einfach überbrückter Tris-σ-homobenzol-Verbindungen (1974)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 107 (1974), S. 1971-1987 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: [2π+2π]-Photocycloaddition Reactions in Tricyclo[3.2.2.02.4]nonadiene Derivatives. Synthesis of Singly Bridged Tris-σ-homobenzene CompoundsThe direct - not, however the acetone sensitized -excitation (λ 〉 280 nm) of the tricyclo-[3.2.2.02,4]nonadiene diester 6a - c and the bis-trifluoromethyl derivatives 6d, e (Δ 〉 230 nm), resp., yields (60-90%) the pentacycles 7a - e resulting from a [2π + 2π]-cycloaddition reaction. A [2π + 2σ]-addition with participation of the cyclopropane ring (leading to 8a - e) is not observed. With comparable selectivity (〉 90% isolated yield) the [2π + 2π]-cyclisation takes place in the 3-oxa-diester 10 (to 11). The tris-σ-homobenzene compounds 7a - e and 11, resp. are thermally isomerized exclusively in a 2σ → 2π-cleavage to the starting dienes 6a - e and 10, resp. (Ea (7a) = 22 kcal/mole; A = 2.2·1012 S-1-1). As exemplary cases the addition of HCl, CH3OH and H2O to the diester 7a and to the dicarboxylic acid 7g, resp., has been studied; in a rather selective way the adducts 13 and 14 (ratio 9:1) are formed in good yields. With the usual attack upon the nonsubstituted edge of the bishomocyclobutadiene partial structure in 7a being sterically hindered, tetracyanoethylene forms the 1:1 adducts 15 and 16.
    Notes: Die direkte - nicht aber die aceton-sensibilisierte -Lichtanregung (λ 〉 280 nm) der Tricyclo[3.2.2.02,4]nonadien-diester 6a - c bzw. der Bis-trifluormethyl-Derivate 6d,e (λ 〉 230 nm) liefert in 60-80 proz. bzw. 90 proz. Ausbeute die aus einer [2π + 2π]-Cycloaddition resultierenden Pentacyclen 7a - e. Eine [2π + 2σ]-Reaktion unter Beteiligung des Cyclopropanringes (zu 8a - e) ist daneben nicht nachweisbar. Gleichermaßen einheitlich (isolierte Ausbeute 〉 90%) verläuft die [2π + 2π]-Cyclisierung im 3-Oxa-Diester 10 (zu 11). Die Tris-σ-homobenzole 7a - e bzw. 11 werden thermisch ausschließlich unter 2σ → 2π-Spaltung zu den Ausgangsdienen der Photoreaktionen 6a - e bzw. 10 isomerisiert (Ea (7a) = 22 kal/mol; A = 2.2·1012s-1). Am Beispiel des Diesters 7a bzw. der Dicarbonsäure 7g wurde die Addition von HCl und CH3OH bzw. Wasser studiert, wobei selektiv die Addukte 13 und 14 (Verhältnis 9:1) in durchweg guten Ausbeuten gewonnen werden. Bei sterischer Behinderung des üblichen Angriffs auf die unsubstituierte Kante des Bishomocyclobutadien-Partialgerüsts in 7a setzt sich TCÄ zu den 1:1-Addukten 15 und 16 um.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19741070620
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  • 8
    Electronic Resource
    Electronic Resource
    [2π + 2π]-Photocycloadditionen in Bicyclo[2.2.2]octadien-Derivaten (1974)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 107 (1974), S. 1957-1970 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: [2π+2π]-Photocycloaddition Reactions in Bicyclo[2.2.2]octadiene DerivativesAs exemplified by the dieser 14a a [2π + 2π]-photocycloaddition in the bicyclo[2.2.2]octadiene skeleton is possible by direct - not, however, by sensitized - excitation. Besides a small fragmentation to dimethylphthalate (and ethylene) no other phototransformation of 14a takes place. With a half-life of ca. 12 min at 19°C the photoproduct 15a is thermally isomerized back to the diene diester 14a. Via a regiospecific addition of HCl, methanol and water to the tetracycles 15a and 15b (H2O) the epimeric products 18, 19 are isolated in a ratio of ca. 9:1. Their structure is elucidated by oxidation of 18c to 21 and 1H-n.m.r. spectroscopic comparison with the isomeric compounds 20 and 22, resp., synthesized by a different route. Towards bishomodienophilic reagents like tetracyanoethylene and dimethyl acetylenedicarboxylate 15a shows the expected reactivity. The addition proceeds at the nonsubstituted edge of the bishomocyclobutadiene unit yielding 24, and 26.
    Notes: Am Beispiel des Diesters 14a wird gezeigt, daß auch im Bicyclo[2.2.2]octadien-Gerüst durch direkte Lichtanregung -nicht jedoch sensibilisiert - eine [2π + 2π]-Cycloaddition möglich ist. Außer einer geringfügigen Fragmentierung zu Phthalsäure-dimethylester (und Äthylen) findet keine konkurrierende Photoumwandlung von 14a statt. Mit einer Halbwertszeit von ca. 12 min bei 19°C isomerisiert sich das Photoprodukt 15a zurück zum Dien-diester 14a. Bei der regiospezifischen Addition von HCl, Methanol und Wasser an die Tetracyclen 15a, 15b (H2O) werden die Epimeren 18, 19 im Verhältnis von ca. 9:1 isoliert. Deren Struktur ist durch Oxidation von 18c zu 21 sowie 1H-NMR-spektrometrischen Vergleich mit den auf anderem Weg synthetisierten Isomeren 20 und 22 gesichert. Auch gegenüber bishomodienophilen Partnern wie Tetracyanäthylen oder Acetylendicarbonsäure-dimethylester besitzt 15a die erwartete Reaktivitat. Die Addition erfolgt stereospezifisch an die nichtsubstituierte Kante des Bishomocyclobutadienteils zu 24 und 26.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19741070619
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  • 9
    Electronic Resource
    Electronic Resource
    A Vibrational Study of Some 1,2,4-Trioxanes (1988)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 71 (1988), S. 992-999 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The vibrational spectra of some 1,2,4-trioxanes present two characteristic bands at 790 and 880 cm-1. On the basis of 18O-isotopic substitution and comparison with analogous compounds, these bands have been assigned to coupled C—O and O—O stretching modes of the C—O—O element.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19880710508
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  • 10
    Electronic Resource
    Electronic Resource
    Thermolysis and Chemiluminescence of Monocyclic 1,2,4-Trioxan-5-ones (1994)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 77 (1994), S. 1851-1860 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The 3,6-substituted 1,2,4-trioxan-5-ones 11-14, on heating to 170-200°, underwent unimolecular thermolysis to generate electronically excited singlet ketones with an efficiency of ca. 0.2%. The chemiluminescence quantum yields (φoSCL) depended on the nature of the 6-substitutents and increased linearly with temperature. The Arrhenius activation energies were obtained by measuring the rate of decay of luminescence and determined as 22.9, 30.4, 35.6, and 34.2 kcal/mol for 11-14, respectively. Step analysis of the chemiluminescence of 14 afforded an average activation energy of 44.3 kcal/mol. This latter result is explicable in terms of two decomposition paths, higher and lower in energy, leading to excited and ‘dark’ products, respectively. The thermolysis of trioxanones 12-14 lacking a H-atom at the 6-position is interpreted as involving successive rupture of the peroxide bond, excision of ketone at the 3-substituted end, and loss of CO2, to finally produce ketone originating from the 6-position (see Scheme 4).
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19940770716
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