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  • 1
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 20 (1840), S. 273-318 
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Theoretical and applied genetics 82 (1991), S. 466-472 
    ISSN: 1432-2242
    Keywords: Brassica oleracea ; Self-incompatibility ; S-locus ; Polymerase chain reaction ; Anther
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The polymerase chain reaction (PCR) is particularly well suited for the detection of rare sequences. Taking advantage of the recent isolation of sequences associated with stigma self-incompatibility inBrassica oleracea, we used PCR amplifications with primers synthesized to the S6 cDNA sequence, to demonstrate the presence of mRNA homologous to stigmaS-locus gene (SLG) in anthers during early microsporogenesis. In addition, otherS-locus-related (SLR) sequences were shown to be transcribed in sexual as well as in vegetative tissues (roots, leaves), suggesting that the SLG family might be involved not only in pollen-stigma recognition, but more generally in various forms of plant cell signalling processes. This information corroborates the recent discovery of a cDNA-deduced protein kinase from maize roots, whose extracellular receptor displays high homology withBrassica S-locus-specific glycoproteins.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Theoretical and applied genetics 70 (1985), S. 628-633 
    ISSN: 1432-2242
    Keywords: Carbon dioxide ; Relative humidity ; Brassica oleracea ; Pollen-pistil interactions ; Self compatibility
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The events of the progamic phase of fertilization have been monitored by in vitro experiments in self compatible (SC), partial self-incompatible (PSI) and self incompatible (SI) lines. The duration of the progamic phase is about 30 h. Treatment with low concentrations of CO2 (3 to 5%) at high relative humidity (rH, 100%) had the following effects: pollen quality, which declines normally during flower ageing, was prematurely reduced; pollen adhesion and germination, both low in SI matings, were increased; the stigma callose response in SI matings was reduced to the low level of SC matings; and the number of pollen tubes in the style after SI matings significantly increased. CO2 concentrations of 4 to 6% applied for 8, 16 or 24 h at 100% rH proved to be the most effective treatment for blocking the SI response in cauliflower.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1572-9788
    Keywords: Brassica oleracea ; immunochemical analysis ; self-incompatibility ; S locus glycoprotein ; SSCP ; stigma
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The self-incompatibility reaction of cruciferous plants prevents self-fertilization and has been shown to be controlled by at least two genes situated at a single multiallelic locus, theS locus. One of these two genes, theS locus glycoprotein (SLG) gene, encodes an abundant glycoprotein secreted to the cell wall of stigma papillae. Identification of thoseS alleles present at theS locus is of prime interest when studying the self-incompatibility response and can be achieved by identifying the SLG of the stigma. Here, we show that using anti-SLG antibodies in an immunochemical analysis, combined with a SSCP (single-strand conformation polymorphism) approach to characterize the corresponding stigma-specific, SLG mRNA, allowed the identification of plants heterogeneous at theS locus among populations of plants that were thought to be homozygous for known SLG alleles. This analysis stresses the importance of testing the homozygosity at theS locus of lines considered inbred for a knownS allele as mix-up of seeds may occur during the breeding programme.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 182 (1981), S. 2225-2231 
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Chiral cadmium thiolates of cysteine with cyclohexyl or (-)menthyl ester groups were prepared and compared with similar compounds (with isopropyl or methyl ester groups) as initiators for stereospecific polymerization of methylthiirane in homogeneous phase. The resulting polymers are highly isotactic and in all cases stereoelection can be reversed with a small change in polymerization temperature. This temperature effect permitted to differentiate two stages in the polymerization corresponding to the formation of a precursor and to that of a high polymer, respectively.
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 184 (1983), S. 1389-1395 
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Polymerization of ethylene initiated in naphta solution by Zr(CH2C6H5)4 at 200°C under high purity conditions showed a cocatalytic effect of water with a maximum rate for a mole ratio H2O/Zr close to 0,1. No activity was observed for the hypothetical compound (C6H5CH2)3ZrOZr(CH2C6H5)3. Ethylene polymerization was also initiated with supported catalysts obtained by reaction of Zr(CH2C6H5)4 with silicium oxide or pre-dried aluminium oxide with an increase of activity (by a factor of 5). The resulting polyethylenes were found to be virtually linear with 1,5 CH3 groups for 1000 C atoms and with melting points of 134 - 136,5°C. They have high molecular weights with very broad distribution. These results were interpreted by a mechanism involving Ziegler-like active centers.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The living stereospecific polymerization of methylthiirane initiated by a chiral cadmium compound was run in different solvents. The general features of the mechanism of stereoregulation are the same as in bulk. In heptane and in heptane/propylene carbonate mixtures, the stereospecificity of the reaction does not depend on monomer concentration and on the dielectric constant ε of the medium. This independence of stereospecificity is in agreement with the absence of a variation of the complexation constant between a model cadmium derivative and the monomer with the variation of ε in a large range. The enantioasymmetric process depends on the molecular weight of the chain bearing the active sites. A change from diastereoisomeric to enantiomeric forms of active sites occurs for molecular weights around 50000. The enantioasymmetric constant depends on the nature of the medium and we observed a Born law for the dependence of the enantioasymmetric constant versus reciprocal dielectric constant: log kR ∝ 1/ε. This effect can be explained by a variation of the reactivities of the two types of active sites and occurs without a change in their relative amounts.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The polymerization of methylthiirane in homogeneous phase initiated by bis(isopropylcysteinato)cadmium is a living process. For low conversions, oligomers (essentially heptamers and octamers) are formed, apparently using one valency of cadmium, the main propagation taking place by using the other one. However, the size of the oligomers may still grow for higher conversions. The mechanism of the oligomer formation depends on the temperature. A “normal” insertion of the monomer is observed at -23°C, whereas at 20°C a disulfide bond is formed. The preferential choice of a different enantiomer in the main propagation reaction may depend on the presence of a particular type of oligomer, in the vicinity of cadmium, linked to the cysteine group. However, stereospecificity (stereoselection and stereoelection) appears only with molecular weights higher than 6000 and also depends on the temperature of propagation: with decreasing temperature, the stereoregularity increases and the stereoelection can be inverted (for a definite oligomer structure).
    Additional Material: 5 Tab.
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Enantioasymmetry was studied for polymerizations of methylthiirane initiated by bis(isopropyl-S-cysteinato)cadmium and run in bulk. The ratio of rates of consumption of the two antipodes is independent of their concentrations. The enantioasymmetric constant kR, measuring the preferential choice of the R-antipode, is depending on both the relative number of the two types of active sites and on their reactivities. An effect on enantioasymmetry of the molecular weight of the growing chains bearing the active sites, is occurring with two distinct stages: The first one is observed, with an enantioasymmetric constant kR = 1,5, from the appearance of stereospecificity up to molecular weights of 35000 (for the main chain) and the second one with kR = 1,07 for molecular weights higher than 35000. In the first stage, the cysteinato end group of the oligomer chain remains linked to cadmium (by cadmium-nitrogen complexation) and the two active sites are diastereoisomers having different reactivities. In the second stage, the macrocyclic oligomer becomes too large and cadmium-nitrogen interaction is suppressed. The active sites are now enantiomers having the same reactivity. In this case, enantioasymmetry depends only on the unbalance between the amounts of the two types of active sites. The maximum size the macrocyclic oligomer can reach depends on the initiator concentration.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 193 (1992), S. 1709-1721 
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: In the living polymerization of methylthiirane initiated with bis(isopropyl-(S)-cysteinato)-cadmium, stereospecificity depends on temperature of propagation, on initiator concentration and also on the length of the growing polymer chain. The kinetics of stereospecific and non-stereospecific processes are described. In both cases, the order with respect to monomer is equal to zero and that with respect to initiator is one-half. The stereospecific propagation is proposed to involve cadmium thiolates associated as “dimeric species” and coordinated by both the monomer and by an oligomeric or polymeric chain.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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