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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Plant molecular biology 23 (1993), S. 1079-1085 
    ISSN: 1573-5028
    Keywords: Brassica ; Solanum ; stigma ; style ; self-incompatibility ; multigenic family
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In this study, the tissue printing technique has been used to rapidly localize in female tissues the presence of specific mRNA representing the products (or some of the products) of the self-incompatibility S-locus gene(s). The methodology, initially developed for Brassica oleracea (sporophytic self-incompatibility) has been successfully employed on Solanum chacoense (gametophytic self-incompatibility). In the Brassica system tissue printing has allowed rapid discrimination between S alleles belonging to class 1 (dominant types) vs. class 2 (recessive types), and thus parallels findings obtained by restriction analyses. In the Solanum system the level of the S-RNase messages was analysed by scanning laser densitometry, and it was found that the message levels of the allele S14 declined faster than those coming from S13 in mature flowers.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1573-5028
    Keywords: Brassica ; class II S haplotypes ; self-compatibility ; self-incompatibility ; SLG glycoproteins ; specific anti-SLG antibodies
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In Brassica, the S-locus glycoprotein (SLG) gene has been strongly implicated in the self-incompatibility reaction. Several alleles of this locus have been sequenced, and accordingly grouped as class I (corresponding to dominant S-alleles) and class II (recessive). We recently showed that a self-compatible (Sc) line of Brassica oleracea expressed a class II-like SLG (SLG-Sc) gene. Here, we report that the SLG-Sc glycoprotein is electrophoretically and immunochemically very similar to the recessive SLG-S15 glycoprotein, and is similarly expressed in stigmatic papillae. Moreover, by seed yield analysis, we observe that both alleles are associated with a self-compatibility response, in contrast with the other known recessive S haplotypes (S2 and S5). By genomic DNA blot analysis, we show the existence of molecular homologies between the Sc and S15 haplotypes, but demonstrate that they are not identical. On the other hand, we also report that the S2 haplotype expresses very low amounts of SLG glycoproteins, although it exhibits a self-incompatible phenotype. These results strongly question the precise role of the SLG gene in the molecular mechanisms that control the self-incompatibility reaction of Brassica.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-2048
    Keywords: Brassica ; Pistil specific gene ; Pollination ; Self-incompatibility ; S-locus glycoproteins ; Transmitting tissue
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In Brassica, self-incompatibility has been correlated with S-locus glycoproteins (SLG) localized at the site of pollen rejection, the stigmatic papillae. In this paper we present immunocytochemical evidence that during development of the pistil SLG proteins accumulate not only in the stigmatic papillae, but also in the transmitting tissue of stigma, style and ovary, along the pathway followed by the pollen tube. This observation was confirmed by the biochemical characterization of stylar and ovarian SLG proteins and by the detection of SLG transcripts in style/ovary tissues by polymerase chain reaction analysis. Thus we demonstrate similarities between the pattern of SLG gene expression in Brassica (sporophytic self-incompatibility system) and that of S products in Nicotiana (gametophytic self-incompatibility system) which may reflect relationships between the self-incompatibility systems. An active role of SLG gene products during the pollen-tube growth in the pistil is discussed.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1617-4623
    Keywords: Brassica ; Flower ; Self-incompatibility ; S locus glycoprotein ; S locus receptor kinase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A new member of the S gene family,SLR3 (S-Locus Related 3), was identified inBrassica oleracea. This gene had a novel pattern of expression compared with previously described members of the family, being expressed in petals, sepals and vegetative apices, in addition to stigmas and anthers. Moreover, use ofSLR3-derived probes in RNA blot and RACE-PCR (rapid amplification of cDNA ends-polymerase chain reaction) experiments has identified transcripts of genes closely related toSLR3 in leaves, cotyledons and, at high levels in developing anthers.SLR3 is not linked to theS locus but is linked to two or three closely related genes. Sequence analysis of theSLR3 gene indicates that it is derived from an ancestral receptor kinase gene that has been modified by a series of deletion events. As a result of these modifications,SLR3 is predicted to encode a secreted glycoprotein lacking both transmembrane and kinase domains. The putativeSLR3 protein differs from the products of most other S gene family members in that several of the highly conserved cysteines have been lost. Within theS gene family, modification of receptor kinase genes by deletion may represent a general mechanism for the generation of genes encoding secreted glycoproteins.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Protoplasma 124 (1985), S. 168-174 
    ISSN: 1615-6102
    Keywords: Pollen ; Brassica ; Sperm cell
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary In mature viable pollen ofBrassica oleracea, the pair of sperm cells and the nucleus of the vegetative cell are linked to form a structured unit we term the male germ unit. The sperm cells are held within a common periplasm and have no cell walls. Each sperm cell has a central globular body containing the nucleus surrounded by several evaginations which provide the means for linkage between them. One sperm cell, usually that closest to the nucleus of the vegetative cell contains most of mitochondria profiles (plastids are absent). This sperm cell appears to be linked by its protoplasmic evaginations to the envelope of the vegetative nucleus. The role of this unit in interactions with the female gametic complex is considered.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Molecular genetics and genomics 255 (1997), S. 514-524 
    ISSN: 1617-4623
    Keywords: Key words Antisense ; Brassica ; Flower ; Self-incompatibility ; S locus receptor kinase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Gene expression can be inhibited by antisense RNA transcripts. Although this phenomenon is widely used to analyse gene function in plants, the molecular mechanisms involved are poorly understood. One approach to improving our understanding of antisense gene regulation is to analyse the function of endogenous antisense transcripts. To date, only a small number of plant genes have been shown to be transcribed in both directions and limited information is available concerning the role of natural antisense transcripts in plants. In this study, we have identified several natural antisense transcripts which hybridise to probes derived from the S locus receptor kinase gene (SRK). The RNase protection assay and reverse trancriptase-PCR were used to demonstrate that a proportion of the antisense transcripts are encoded directly by SRK. Using different RNase protection probes, regions of the promoter, exon I (which encodes the S domain) and intron I of SRK were shown to be transcribed in an antisense direction. An antisense SRK transcript was shown to inhibit translation of a sense transcript in vitro. The possible role of antisense SRK transcripts in vivo is discussed.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Chemistry Edition 12 (1974), S. 1001-1010 
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The polymerization in bulk of racemic tert-butyl thiirane with a chiral initiator resulting from the reaction between diethylzinc and (—)3,3-dimethyl-1,2-butanediol produces an optically active polymer by preferential consumption of R enantiomer. The unreacted monomer is enriched in S enantiomer. The relative rate r of consumption of R enantiomer versus S enantiomer is as high as 2.8. Obtained polymer could be separated into two crystalline fractions: an optically active fraction, formed from regular sequences of R type enantiomeric units, and an optically inactive fraction which corresponds to a racemate. Experimental results are consistent with a stereospecific mechanism of addition, the two enantiomers being chosen by two different type of sites. The stereoelective process is due to an unequal number of these two types of sites.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Chemistry Edition 17 (1979), S. 1595-1604 
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The kinetics of enantiomerically enriched t-butyl thiirane was studied. The stereoelectivity and the kinetic behavior are not changed when a monomer of an initial enantiomeric composition lower than a defined limit value is used. When the enantiomeric composition is higher than this value, the stereoelectivity increases. In agreement with kinetic results, a mechanism is proposed involving, in a first step, the complexation of monomer on preexisting sites of the initiator with formation of highly selective chiral active species on which propagation occurs.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Chemistry Edition 17 (1979), S. 1583-1593 
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The stereoelective polymerization of racemic t-butyl thiirane was performed with chiral zinc glycolate. Monomers and polymers of high optical purities were isolated. A new kinetic scheme in which the ratio of the rates of consumption of both enantiomers obeys a second-order relationship is proposed. This behavior is different from that observed for other three-membered ring monomers.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Chemistry Edition 17 (1979), S. 1605-1610 
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The effect of temperature on stereoelective polymerization of t-butyl thiirane was studied. Although the overall kinetic scheme was not modified by a change of temperature, a strong effect on the stereoelectivity ratio was observed. Very high optical yields were obtained for polymerizations run below 0°C. On the other hand, at temperatures higher than 120°C, the stereoelection is inversed; i.e., the opposite enantiomer is chosen. The stereoselectivity ratio varies with temperature according to an Arrhenius relationship.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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