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  • 1
    Electronic Resource
    Electronic Resource
    Ueber die Constitution der organischen Säuren u. s. w.Fortsetzung von Bd. XIX. 312. (1840)
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 20 (1840), S. 273-318 
    Details
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/prac.18400200143
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  • 2
    Electronic Resource
    Electronic Resource
    The mentor pollen phenomenon in poplars: a new concept (1989)
    Springer
    Theoretical and applied genetics 78 (1989), S. 129-135 
    Details
    ISSN: 1432-2242
    Keywords: Mentor effect ; Interspecific incompatibility ; Populus ; Male-male interaction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The mentor effect has been investigated in poplars. Attempts to overcome interspecific incompatibility are analysed by pollen germination and pollen tube behaviour in situ, both for compatible and incompatible crosses. We have demonstrated that following the mixed pollination, the two pollen sets interact at different levels of the progamic phase. A hypothetical model is proposed which describes mentor effect as the result of interactions of antagonist and cynergic forces applying on compatible pollen and tubes. These forces promote pollen tube growth both on the female partner surface and within the tissues.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00299765
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  • 3
    Electronic Resource
    Electronic Resource
    Localization of adenylate cyclase activity in Populus: its relation to pollen-pistil recognition and incompatibility (1988)
    Springer
    Sexual plant reproduction 1 (1988), S. 140-149 
    Details
    ISSN: 1432-2145
    Keywords: Interspecific incompatibility ; Stigma-pollen interactions ; Adenylate cyclase ; Cytochemistry ; Populus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Adenylate cyclase has been localized cytochemically in female and male parents as well as during the pollen-stigma interaction with an original technique employing strontium as the capture ion and adenyl imidodiphosphate as the specific substrate. The specificity of the reaction was checked by using several controls. No final specific reaction product was detected in unpollinated P. deltoides stigmas or in the P. deltoides or P. alba pollen grains used for compatible and incompatible pollinations. In the compatible cross between P. deltoides × P. deltoides, fine dense precipitates were observed in the dictyosomes and the plasma membrane and exterior to the exine of hydrated pollen grains adhering to the stigma surface. Labeling of the stigmatic pellicle was also observed after pollen adhesion and hydration. This was accompanied by a strong reactivity of the cell wall and plasmalemma of the stigma papillae at the sites of pollen tube germination on the stigma surface and at the sites of penetration of pollen tubes between adjacent papillae. In the incompatible cross between P. deltoides x P. alba, adenylate cyclase activity was still present but reduced at the stigma surface following adhesion, hydration, and germination of P. alba pollen. This activity was completely abolished after the penetration of pollen tubes between stigma papillae. These findings suggest that in Populus, adenylate cyclase activity is correlated to pollen adhesion, hydration, and germination at the stigma surface, and that the abolition of this enzyme activity could be one of the cellular events governing the gametophytic phenotype of incompatibility in the cross between P. deltoides and P. alba.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00193744
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  • 4
    Electronic Resource
    Electronic Resource
    Interspecific incompatibility in Populus: inhibition of tube growth and behaviour of the male germ unit inP. deltoides×P. alba cross (1992)
    Springer
    Protoplasma 168 (1992), S. 107-110 
    Details
    ISSN: 1615-6102
    Keywords: Callose ; Interspecific incompatibility ; Male germ unit ; Pollen tube ; Populus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary In order to better understand the cellular events controlling interspecific incompatibility in the genus Populus, the incompatible cross betweenP. deltoides andP. alba has been investigated both at the light and electron microscopic levels. Stained in decolourized aniline blue and observed by epifluorescence microscopy, most incompatible pollen grains are seen to germinate at the stigma surface. Numerous incompatible pollen tubes reach the base of the style where they are arrested 19 h after pollination. Ultrastructural observations on in vivo growing incompatible pollen tubes confirm these data. Very few cytoplasmic modifications are seen within living pollen tubes reaching the lower end of the style or within arrested ones, except the presence of polymorphic plastids. In this predominantly tricellular system, the male germ unit (MGU) is apparently initiated at pollen maturity as an association between the vegetative nucleus and sperm cells. It is maintained during pollen tube growth within the style and persists within arrested incompatible pollen tubes. The unique observation of an association between a dividing generative cell at metaphase and the vegetative nucleus is also reported. Arrested pollen tubes are characterized by apical deformations and accumulation of callose within their thickened cell walls. These cytological data provide additional information on the cellular events associated with interspecific incompatibility in Populus.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01666256
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  • 5
    Electronic Resource
    Electronic Resource
    Purification, crystallization, and preliminary X-ray analysis of PepX, an X-prolyl dipeptidyl aminopeptidase from Lactococcus lactis (1995)
    New York, NY : Wiley-Blackwell
    Proteins: Structure, Function, and Genetics 23 (1995), S. 278-281 
    Details
    ISSN: 0887-3585
    Keywords: overproduction ; crystallography ; X-prolyl dipeptidyl aminopeptidase ; PepX ; Lactococcus lactis ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The X-prolyl dipeptidyl aminopeptidase PepX, a serine peptidase isolated originally from Lactococcus lactis subsp lactis NCDO 763, was cloned and overproduced in Escherichia coli. The enzyme was isolated in its active form in two purification steps. Crystals of PepX were grown by the hanging drop vapor diffusion method using polyethyleneglycol 4000 as precipitant at pH 5.0. The crystals are orthorhombic with cell dimensions a = 92.8 Å, b = 102.6 Å, and c = 101.6 Å, space group P21212, and probably contain one monomer of 87.5 kDa in the asymmetric unit. The crystals, very stable under X-rays, diffract to at least 2.2 Å and are suitable for high-resolution structural analysis. © 1995 Wiley-Liss, Inc.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/prot.340230216
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  • 6
    Electronic Resource
    Electronic Resource
    Crystallization of the RNA-binding domain of the transcriptional antiterminator protein sacy from Bacillus subtilis (1997)
    New York, NY : Wiley-Blackwell
    Proteins: Structure, Function, and Genetics 28 (1997), S. 590-594 
    Details
    ISSN: 0887-3585
    Keywords: SacY ; antiterminator ; RNA-binding motif ; crystallization ; x-ray crystallography ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: SacY is the antiterminator protein involved in the induction by sucrose of the expression of the levansucrase gene (sacB) of Bacillus subtilis. In the presence of sucrose, SacY is activated and prevents premature termination of transcription by binding to a RNA-antiterminator (RAT) sequence partially overlapping with the terminator sequence. SacY consists of a RNA-binding N-terminal domain, SacY(1-55), and a regulatory domain, SacY(56-280), sensitive to the sucrose concentration. SacY(1-55) is in itself capable of binding to the RAT sequence and preventing termination independently of the sucrose concentration. In this paper we describe the overexpression, the purification, and the crystallization of SacY(1-55). We obtained six different crystal forms, some of them diffracting to high resolution (〉1.5 Å). Self rotation function calculations indicated the presence of a dimer in the asymmetric unit, which is in agreement with a proposed oligomeric state in solution as observed by high-resolution NMR measurements. The crystallization of some site-directed cysteine mutants opens the way of solving the structure by multiple isomorphous replacement. Proteins 28:590-594, 1997. © 1997 Wiley-Liss, Inc.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Living enantiosymmetric and enantioasymmetric polymerization of methylthiirane in homogeneous phase (1991)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 3 (1991), S. 484-491 
    Details
    ISSN: 0899-0042
    Keywords: propylene sulfide ; cadmium thiolate ; stereospecific polymerization ; living polymerization ; anionic polymerization ; ring-opening polymerization ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The polymerization of racemic methylthiirane in homogeneous phase, initiated by bis(isopropyl-S-cysteinato) cadmium is a living process. The resulting polymers are isotactic and optically active at partial conversion. The optical purity of the residual monomer may reach 27% at half conversion. The propagation occurs mainly on one valency of Cd, however oligomers grow slowly on the second valency. The stereoregularity of the polymer chain appears only when the length of the oligomer becomes high enough, making possible a bicoordination of the Cd counterions. The stereoregularity of the polymer is characterized by the molar fraction σ of isotactic diads which varies from 0.5 for atactic chains - formed at the beginning - to about one for isotactic segments formed for longer chains. The stereospecifictity also depends on temperature of propagation and on initiator concentration. The kinetics observed (zero order in monomer and one-half in Cd) are explained by monomer coordination before insertion and dimeric association of the thiolate end groups. The enantioasymmetric process observed results from an unbalance in the number of the two different types of active sites and possibly from a difference in their reactivities. Enantioasymmetry has been found to decrease significantly when the dielectric constant ε of the medium increases.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530030614
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  • 8
    Electronic Resource
    Electronic Resource
    Propylene polymerization in a semibatch slurry reactor over supported TiCl4/MgCl2/ethyl benzoate/triethyl aluminum catalyst. I. Catalytic behavior (1989)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 37 (1989), S. 1605-1623 
    Details
    ISSN: 0021-8995
    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
    Notes: High activity TiCl4/MgCl2/ethyl benzoate (EB)/triethyl aluminum (TEA) catalysts for the polymerization of propylene were synthesized and characterized for particle size distribution and crystallinity. Polymerization was carried out in a semibatch, constant pressure slurry reactor. A correction for interfacial mass transfer was found to be necessary to relate the monomer feed rate to the instantaneous rate of polymerization. Without such a correction serious misinterpretation of rate data could result. Optimum productivity was observed with respect to the Al/Ti ratio. Similar behavior was observed with polymerization temperature. Isotacticity increased with polymerization tamperature and decreased with Al/Ti ratio. The addition of a small amount of 2,2,6,6-tetramethylpiperidine increased the percentage of isotactic polypropylene to 98% without significantly affecting productivity.
    Additional Material: 14 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1989.070370615
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  • 9
    Electronic Resource
    Electronic Resource
    Propylene polymerization in a semibatch slurry reactor over supported TiCl4/MgCl2/ethyl benzoate/triethyl aluminum catalyst. II. A kinetic study based on a multisite model (1989)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 37 (1989), S. 1625-1644 
    Details
    ISSN: 0021-8995
    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
    Notes: In propylene polymerization over TiCl4/MgCl2/ethyl benzoate (EB)/triethyl aluminum (TEA) catalysts, experimental evidence strongly suggests that active sites have differing propagation and termination rate constants. Although the chemical structure of these sites may be quite similar, their location on the support may affect their polymerization activity, and this results in a distribution of the propagation and deactivation rate constants. To model this type of system, we developed a kinetic model accounting for multiple active sites. The model was fitted to simulated polymerization data to investigate the validity of mathematical approximations used in the derivation of the model equation. Using experimental data, the adequacy of the model was tested, and the statistical inference of parameter estimation was also discussed. The effects of experimental operating variables and additives on the kinetic model parameters revealed an important insight into the fundamentals of this system. The optimum productivity commonly observed has been shown to be the result of differing rates of increase of both propagation and termination rates with Al/Ti ratio and temperature. Kinetic evidence also suggests that the additive selectively poisons atactic-specific sites.
    Additional Material: 15 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1989.070370616
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  • 10
    Electronic Resource
    Electronic Resource
    Ring Expansion - Formation of Optically Active 3-Hydroxypiperidines from Pyrrolidinemethanol Derivatives (1999)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1999 (1999), S. 1693-1699 
    Details
    ISSN: 1434-193X
    Keywords: Pyrrolidines ; Piperidines ; Nitrogen heterocycles ; Rearrangements ; Aziridinium ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Treatment of pyrrolidinemethanol derivatives (-)-1, (-)-6, (-)-7, 8, (-)-9, (+)-10, (-)-11, and (-)-21 with trifluoroacetic anhydride and then with Et3N afforded, after hydrolysis of the trifluoroacetyl group with NaOH, the optically active 3-hydroxypiperidines (-)-14, (+)-15, (-)-16, 17, (+)-18, (-)-19, (-)-20, and (+)-22, respectively. The yields are good and the enantiomeric excess excellent (up to 95 %).
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
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