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  • 2000-2004  (33)
  • 1990-1994  (4,676)
  • 1955-1959  (2,465)
  • Organic Chemistry  (6,983)
  • Brassica napus
  • genetic engineering
  • particle bombardment
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  • 1
    ISSN: 1570-7458
    Keywords: Ceutorhynchus assimilis ; Trichomalus perfectus ; Brassica napus ; cabbage seed weevil ; parasitoid ; oilseed rape ; spatio-temporal distribution ; SADIE
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The spatio-temporal distribution of Ceutorhynchus assimilis Payk. (Coleoptera: Curculionidae) adults caught in a rectangular grid of flight traps in a crop of winter oilseed rape (Brassica napus L.) was mapped and was analysed using Spatial Analysis by Distance IndicEs (SADIE). Their distribution was compared to that of their larvae and that of their parasitoid Trichomalus perfectus (Walker) (Hymenoptera: Pteromalidae) in pods. The distribution of immigrating C. assimilis adults was consistent with their arrival at the crop boundaries and movement within the crop towards its centre. Adult C. assimilis were aggregated at all times, invasion being on two fronts, leading to the formation of two major clusters within the crop. Large areas of the crop remained relatively unpopulated. During the emigration phase, numbers declined simultaneously in all parts of the crop. The distributions of adult and larval C. assimilis and of larval T. perfectus were spatially associated. The distribution of the parasitoid did not show a density dependent relationship with that of its host. We discuss the movements of insects which underlie their population distributions, the value of integrating spatial information into improved management strategies for C. assimilis and the potential for the spatial targeting of insecticides to reduce the amount applied and to conserve T. perfectus.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-2145
    Keywords: Key words Freeze-substitution ; Transmission electron microscopy ; Brassica napus ; Tapetum ; Microspore ; Immunogold
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  The method of rapid freeze-fixation and substitution was used with Brassica napus floral bud material in order to improve the preservation of microspore and tapetal organelle structure. When observed using transmission electron microscopy, the appearance of the freeze-substituted material differs in a number of ways from the chemically-fixed material previously studied, in particular for the lipid-rich elaioplasts and tapetosomes in the tapetal cells. The tapetosomes have a very electron-dense, opaque appearance when visualized after rapid fixation. In addition, we were able to observe other cytoplasmic details such as pockets in the endoplasmic reticulum and cytoskeletal structures such as microfilaments. Extracellular material was also well-preserved; for example, the fibrous material in the baculae of the developing microspore exine was also visible. Finally, in the freeze-fixed sections specific structures such as elaioplasts could be labelled by antibodies, which indicates that this method preserved protein epitopes that were destroyed by chemical fixation.
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  • 3
    ISSN: 1432-2145
    Keywords: Key words Gene-specific expression ; skp1-like gene ; GUS staining ; Gametophytic expression ; Brassica napus ; Arabidopsis thaliana
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  We isolated a gene, BnSKP1γ1, expressed in rapeseed (Brassica napus) microspores, which encodes a protein closely related to the Saccharomyces cerevisiae Skp1p protein previously shown to play a role in cell cycle regulation. Twelve SKP1-related genes have already been identified in the Arabidopsis thaliana genome. Using a PCR-based strategy, we isolated three other genes. To date, most data available concerning the function of the SKP1-related genes in plants are indirect. Studies on transgenic A. thaliana plants showthat a 1100-bp BnSKP1γ1 promoter fragment can direct GUS expression in female gametophytes soon after the first haploid mitosis and in male gametophytes from the tetrade stage. No GUS expression can be detected in sporophytic tissues. RT-PCR experiments suggest that this gene is expressed in a similar way in rapeseed. This is the first reported case of a gene exhibiting such an expression pattern in angiosperms.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Theoretical and applied genetics 100 (2000), S. 895-898 
    ISSN: 1432-2242
    Keywords: Key words Diallel analysis ; Regeneration ability ; Cotyledonary culture ; Brassica napus ; Heritablity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  Genetic analysis of shoot regeneration from cotyledonary explants of Brassica napus was carried out by 7×7 diallel crosses using cultivars showing a different ability for regeneration. Both additive and dominant effects were significant, with the additive effect being more important than the dominant one. Dominant genes had a positive effect on shoot regeneration. Non-allelic interaction and average maternal effects were not detected, while specific the maternal one was significant. In the 5×5 sub-diallel table, the maternal effect became nonsignificant. The mean degree of dominance was 0.759. Broad- and narrow-sense heritabilities were 0.973 and 0.819, respectively, indicating that shoot regenera- tion ability can be easily transferred into economically important cultivars showing a low or an unresponsive ability.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1432-2242
    Keywords: Key words. Fertility Restoration (Rf) ; Cytoplasmic male sterility (CMS) ; Raphanus sativus L. ; Brassica napus ; Mitochondria
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  The genetics of fertility restoration (Rf) of kosena radish CMS has been characterized. The kosena CMS-Rf system is genetically the same as that of the ogura CMS-Rf system. Two dominant genes that act complementary to the restoration of fertility control fertility restoration in kosena CMS. One allele (Rf1) is associated with accumulation of the CMS-associated protein, ORF125. The interaction of Rf1 and another allele (Rf2) was essential for the restoration of fertility in radish, whereas Rf1 alone was sufficient for the complete restoration of fertility in the B. napus kosena CMS cybrid.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Plant cell reports 19 (2000), S. 1177-1183 
    ISSN: 1432-203X
    Keywords: Keywords Rapid-cycling ; Brassica napus ; Somatic embryogenesis ; Secondary embryogenesis ; Regeneration ; In vitro Howering ; AbbreviationsABA: Abscisic acid ; BAP: 6-Benzyl-aminopurine ; DAP: Days after pollination ; 2-iP: 6-(γ, γ-dimethlyallyl-amino)purine ; Kinetin: 6-Furfurylaminopurine ; MS: Murashige and Skoog ; SE0: Somatic embryo from seed ; SE1: First-generation secondary embryo ; SE2: Second-generation secondary embryo ; Zeatin: 6-(4-hydroxy-3-methylbut-trans-2-enylamino)purine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  A simple method to induce somatic embryogenesis from seeds of rapid-cycling Brassica napus is described. Seedlings cultured on Murashige and Skoog (MS) basal medium produced somatic embryos directly on hypocotyls and cotyledons after 2 to 3 subcultures onto the same medium. A low pH of the medium (3.5–5) was more conducive to somatic embryogenesis than a higher pH (6 and 7). Embryogenic potential of the seeds was inversely correlated to seed age: about 41–68% of immature seeds between the ages of 14 and 28 days after pollination (DAP) formed somatic embryos compared to 0–11% of the seeds obtained 29–37 DAP. About 54% of the somatic embryos produced secondary embryos after subculturing onto the same medium. The embryogenic potential of the cultures has been maintained on MS basal medium for 2 years (12 generations) without diminution. Up to 75% of the secondary embryos developed into plantlets on MS medium enriched with 10–6  M zeatin, and 40% of these produced flowers when transferred to an optimised flower-induction medium. Viable seeds were produced in self-pollinated in vitro flowers.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1573-9368
    Keywords: Hyoscyamus muticus ; particle bombardment ; transformation ; tropane alkaloids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We report an efficient whole plant transformation system for Hyoscyamus muticus, an important medicinal plant of the Solanaceous family. We developed a system using a plasmid carrying the nptII and gusA genes, which was delivered into leaf explants by particle bombardment. Ten percent of bombarded leaf explants formed kanamycin-resistant callus, from which putative transgenic plants were recovered. The nptII gene conferring kanamycin resistance was found to be incorporated into the genome of all transgenic plants screened. Over 50% of the kanamycin resistant plants showed strong expression of the non-selected gusA gene. The majority of transgenic plants reached maturity, could be self pollinated, and produced fertile seed. A simple and efficient whole plant transformation system for this medicinal plant is an important step in furthering our understanding of tropane alkaloid production in plants.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1573-9368
    Keywords: direct transformation ; haploid plant ; Marchantia polymorpha ; particle bombardment ; plant regeneration ; stable integration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Thalli of the haploid liverwort Marchantia polymorpha were successfully used for direct particle bombardment with plasmid pMT, which carries a hygromycin phosphotransferase gene (hpt) controlled by the CaMV 35S promoter and the NOS polyadenylation region. Hygromycin-resistant cell masses arose from the thallus surface and developed directly into hygromycin-resistant thalli. Southern blot analyses indicated that these thalli carried at least 1–4 copies of the hpt gene, which were stably transmitted to their asexual thallus progenies via gemma propagation for three generations. This transformation and direct plant regeneration protocol is expected to be a valuable tool for the molecular analysis of this lower land plant.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    International journal of technology and design education 10 (2000), S. 239-254 
    ISSN: 1573-1804
    Keywords: contexts ; critical reflection ; environment ; ethics ; genetic engineering ; impacts ; values
    Source: Springer Online Journal Archives 1860-2000
    Topics: Art History , Education , Technology
    Notes: Abstract Design and technology education aims to prepare young people for living in a rapidly changing technological society which will involve them in making many value judgements, some with complex ethical dimensions. Key aspects of the ethical judgements in relation to genetic engineering are examined: the hidden assumptions, the inevitable unpredictability when dealing with living processes highly interactive with the surroundings, the commercial and political pressures, and the underlying `world-views' and values. It is argued that responsible judgements therefore require wide consultation, sensitivity to social, cultural and moral issues, acknowledgement of the political and economic context, and above all, critical reflection on the beliefs and commitments that are shaping the vision and the drive. Teaching and learning strategies are needed that highlight the social and environmental context of technological activity, that encourage pupils to consider what determines the quality of their own lives and those of others, and that stimulates reflection on the values and beliefs which influence the priorities when value judgements are being made.
    Type of Medium: Electronic Resource
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  • 10
    ISSN: 1572-9788
    Keywords: cotransformation ; gna gene ; insect resistance ; Oryza sativa L. ; particle bombardment ; transgenic Thai rice
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract We used particle bombardment to transform two elite Thai rice varieties, Khao Dawk Mali 105 (KDML105) and Supanburi 60 (SP60), with the snowdrop lectin gene gna (Galanthus nivalis agglutinin). This gene confers resistance to sap-sucking insects such as the brown planthopper (BPH; Nilaparvata lugens), which is one of the most damaging pests of rice. Traditionally, KDML105 and SP60 have been regarded as recalcitrant to transformation, and this is the first account of successful gene transfer to these varieties. By molecular analysis, we confirmed the recovery of over thirty gna-transgenic lines. GNA protein expression was characterised by western blot analysis, and we achieved expression levels of up to 0.25% total soluble protein. GNA-producing R1 transgenic plants were significantly more resistant to BPH than control plants (P〈0.0001), with 37% and 42% reduction in nymphal survival for constitutive and phloem-specific expression, respectively. Transferring the gna gene to these superior rice varieties thus represents a major step forward for crop improvement in Thailand, and should help to reduce the damage caused by rice pests, and hence increase yields for this vital domestic and export market.
    Type of Medium: Electronic Resource
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  • 11
    ISSN: 1615-6102
    Keywords: Actin microfilament ; Brassica napus ; Cytochalasin D ; Microspore embryogenesis ; Microtubule ; Preprophase band
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Changes in the actin filament and microtubule cytoskeleton were examined during heat- and cytochalasin D-induced embryogenesis in microspores ofBrassica napus cv. Topas by rhodamine phalloidin and immunofluorescence labelling respectively. The nucleus was displaced from its peripheral to a more central position in the cell, and perinuclear actin microfilaments and microtubules extended onto the cytoplasm. Heat treatment induced the formation of a preprophase band of microtubules in microspores; preprophase bands are not associated with the first pollen mitosis. Actin filament association with the preprophase band was not observed. The orientation and position of the mitotic spindle were altered, and it was surrounded with randomly oriented microfilaments. The phragmoplast contained microfilaments and microtubules, as in pollen mitosis I, but it assumed a more central position. Cytoskeletal reorganisation also occurred in microspores subjected to a short cytochalasin D treatment, in the absence of a heat treatment. Cytochalasin D treatment of microspores resulted in dislocated mitotic spindles, disrupted phragmoplasts, and symmetric divisions and led to embryogenesis, confirming that a normal actin cytoskeleton has a role in preventing the induction of embryogenesis.
    Type of Medium: Electronic Resource
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  • 12
    Electronic Resource
    Electronic Resource
    Springer
    Euphytica 114 (2000), S. 217-221 
    ISSN: 1573-5060
    Keywords: Brassica napus ; flower receptacle segments ; in vitro ; culture ; pollinated ovaries ; Raphanus sativus var. raphanistroides/kwd〉
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Oil radish (Raphanus sativus var. raphanistroides Makino) is resistant to drought and low temperature. In order to breed more resistant cultivars of rapeseed, the wide cross between rapeseed (Brassica napus L.) and oil radish was made. Rapeseed was not compatible with oil radish, and the frequency of hybrid plants (F1) was very low. Moreover, the hybrid plants were sterile. In order to recover the intergeneric hybrids (F1), the in vitro organ culture technique was applied in our experiments. The frequency of hybrid plants (F1) was increased up to 25.55% by means of in vitro culture of pollinated ovaries. Some fertile amphidiploid hybrid plants were obtained by means of colchicine treatment of small buds obtained from cultured flower receptacle segments of hybrid plants (F1). It is suggested that the technique of in vitro culture of pollinated ovaries and flower receptacle segments is useful in the wide-cross breeding of rapeseed.
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  • 13
    ISSN: 1573-5060
    Keywords: Brassica napus ; doubled haploids ; high oleic acid rapeseed (HOAR) ; in vitro selection ; microsporeculture ; mutants
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Microspore derived embryos (MDEs) in Brassica napuscontain large amounts of storage lipids which show a genotype specific fatty acid composition (FAC). One cotyledon of regenerating emblyos can be dissected at an early stage during the in vitro culture and used for fatty acid analysis. Thus, in breeding programmes to modify oil quality, only MDEs having the desired FAC need to be regenerated to plantlets and transferred to the greenhouse. In the present study the applicability of this method for the selection of a high oleic acid content and a low linoleic acid content in the seed oil has been tested by crossing a Brassica napus mutant line having a high oleic acid (C18:1) content in the seed oil (75%) with a wild type doubled haploid line with 62% C18:1 in the seed oil. Microspore culture was applied to the F1 plants. In total 59 MDEs were obtained, from which 31 were cultured with and 28 without 15μM abscisic acid for 3 weeksin vitro. One cotyledon was dissected under aspetic conditions and used for fatty acid analysis. The remaining part of the embryos were further regenerated to plantlets and transferred to the greenhouse to obtain seeds after self pollination. Seeds harvested from the doubled haploid lines in the greenhouse were used for fatty acid analysis and also for growing in the field. The abscisic acid treatment of the MDEs generally improved the correlations for linoleic and oleic acid between the MDEs and the seeds harvested in the greenhouse and the field. The correlations ranged from 0.68** to 0.81**.This indicates that selection for high oleic acid can be started already during an early stage of the in vitro culture.
    Type of Medium: Electronic Resource
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  • 14
    ISSN: 1573-5060
    Keywords: Brassica napus ; hybrid seed production ; self-incompatibility ; swedes, rutabaga
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Procedures for producing seed of hybrid swedes using self-incompatibility were examined. Single-cross, double-cross and modified double-cross hybrids were compared in isolation plots using natural pollinators and in polythene tunnels using blow-flies. With good coincidence of flowering and the same flower colour, nearly 100% hybrid seed was produced by natural pollinators with the single-crosses, the double-cross and one of the two modified double-cross hybrids; the other modified double-cross hybrid produced 87%hybrid seed. With poor coincidence of flowering and different flower colours the proportion of hybrids dropped to 61%. Using different flower colours and blow-flies as pollinators in polythene tunnels, higher levels of outcrossing were produced than in isolation plots with natural pollinators; the opposite result was obtained when the same flower colour was used.
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  • 15
    ISSN: 1573-5060
    Keywords: Brassica napus ; germination test ; herbicidetolerance screening ; monitoring ; PAT-ELISA ; PCR
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract A novel screening test is described for the discrimination of transgenic phosphinothricin tolerant oilseed rape from non transgenic rape seedlings. The method is based on the germination of rape seeds on filter paper soaked with a 0.005% phosphinothricin solution. Under these conditions inhibition of seedling development by the herbicide can be observed after 10 days. The germination test gains an advantage over the routinely used herbicide spraying, because it is rapid, needs little space and allows efficient screening of huge numbers of seeds. The assay has been successfully applied to the screening of different transgenic and non transgenic rapeseed varieties/lines and has been compared to other methods such asBasta® spray test, drop test, ELISA-technique and PCR-amplification of the pat gene. This test allows on one hand large screening programmes to monitor the foreign gene in the environment and on the other quality control of seedlots before market introduction of herbicide tolerant oilseed rape.
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  • 16
    Electronic Resource
    Electronic Resource
    Springer
    Photosynthesis research 64 (2000), S. 137-146 
    ISSN: 1573-5079
    Keywords: Brassica napus ; chlorophyll ; chlorophyll catabolite ; degradation ; porphyrin ; senescence ; tetrapyrrole
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Chlorophyll catabolism accompanying leaf senescence is one of the most spectacular natural phenomena. Despite this fact, the metabolism of chlorophyll has been largely neglegted until recently. Oilseed rape has been used extensively as a model plant for the recent elucidating of structures of chlorophyll catabolites and for investigation of the enzymic reactions of the chlorophyll breakdown pathway. The key reaction which causes loss of green color is catalyzed in a two-step reaction by pheophorbide a oxygenase and red chlorophyll catabolite reductase. In this Minireview, we summarize the actual knowledge about catabolites and enzymes of chlorophyll catabolism in oilseed rape and discuss the significance of this pathway in respect to chlorophyll degradation during Brassica napus seed development.
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  • 17
    ISSN: 1573-5028
    Keywords: transgenic cereals ; molecular pharming ; antibodies ; carcinoembryonic antigen ; single-chain Fv fragment ; particle bombardment
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract This report describes the stable expression of a medically important antibody in the staple cereal crops rice and wheat. We successfully expressed a single-chain Fv antibody (ScFvT84.66) against carcinoembryonic antigen (CEA), a well characterized tumor-associated marker antigen. scFv constructs were engineered for recombinant antibody targeting to the plant cell apoplast and ER. Up to 30 μg/g of functional recombinant antibody was detected in the leaves and seeds of wheat and rice. We confirmed that transgenic dry seeds could be stored for at least five months at room temperature, without significant loss of the amount or activity of scFvT84.66. Our results represent the first transition from model plant expression systems, such as tobacco and Arabidopsis, to widely cultivated cereal crops, such as rice and wheat, for expression of an antibody molecule that has already shown efficacy in clinical applications. Thus, we have established that molecular pharming in cereals can be a viable production system for such high-value pharmaceutical macromolecules. Our findings provide a strong foundation for exploiting alternative uses of cereal crops both in industrialized and developing countries.
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  • 18
    Electronic Resource
    Electronic Resource
    Springer
    Journal of chemical ecology 26 (2000), S. 1411-1422 
    ISSN: 1573-1561
    Keywords: Brassica napus ; defense-related proteins ; environmental effects ; induced defenses ; proteinase inhibitors ; regulation ; resistance ; trypsin inhibitors ; variation ; wounding
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract We examined several environmental and developmental influences on trypsin inhibitor (TI) activity in leaves of young Brassica napus seedlings in a series of greenhouse experiments. In seedlings of B. napus cv. Westar, TI activity is constitutively present and exhibits a rise then fall through time in the first true leaves of young plants. TI activity is induced by wounding in the first true leaves, but the degree of induction is relatively insensitive to the degree of wounding over a gradient of 5–15% of leaf area damage. TI activity is enhanced in first true leaves of plants in which the cotyledons have been wounded relative to plants in which the cotyledons have not been wounded. TI activity is also enhanced in the second true leaves on plants in which the first true leaves have been wounded. The degree of systemic induction in second true leaves declines additively with plant age, but local induction in the first true leaves is not affected by age. In B. napus cv. Gido, TI activity is constitutively present but is not locally wound-inducible in first true leaves of young plants exposed to the same wounding gradient as cv. Westar. In unwounded plants at the six-leaf stage, TI activity is higher in second true leaves than in fifth true leaves, indicating that TI activity is developmentally regulated in this cultivar.
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  • 19
    ISSN: 1573-1561
    Keywords: Brassica napus ; Pratylenchus neglectus ; nematode ; 2-phenylethyl glucosinolate ; isothiocyanate ; pest resistance ; disease break ; variability ; genetic analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Root concentrations of 2-phenylethyl glucosinolate in canola, Brassica napus, influence the susceptibility of the crop to the root lesion nematode (Pratylenchus neglectus), as well as the nematicidal effect of root tissues as they degrade in the soil. Plants containing high 2-phenylethyl glucosinolate should therefore reduce soil populations of P. neglectus. A selection program was developed to increase the proportion of total glucosinolates contributed by 2-phenylethyl glucosinolate in the roots of B. napus cv. Dunkeld. Variation within this accession was observed to be stable across the S1 and S2 generations. The segregation observed for 2-phenylethyl glucosinolate percentage suggested that the trait was encoded at a single locus, with the "high" phenotype being dominant. Plants with the high 2-phenylethyl glucosinolate phenotype (〉45% of total glucosinolates) were shown to be significantly more resistant to P. neglectus than otherwise identical "low" phenotypes (〈45% of total).
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  • 20
    ISSN: 1572-994X
    Keywords: plant viral promoter ; caulimovirus ; strawberry vein banding virus ; zucchini yellow mosaic virus ; particle bombardment
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract A putative promoter from the strawberry vein banding caulimovirus (SVBV) genome was identified by its ability to drive infection with full-length cDNA of the zucchini yellow mosaic RNA potyvirus (ZYMV). A high rate of infection was obtained with the cDNA under control of the SVBV promoter using particle bombardment technology. The SVBV promoter shows 60% homology to the cauliflower mosaic virus 35S promoter in the domain spanning the conserved motifs of CCACT (at −83) and the TATA box (at −31), to the transcription start. The 3′-end one-third of the putative promoter (328 bp) was sufficient to invoke full infectivity with the ZYMV clone, and drove transient reporter gene expression in Solanaceae and Cucurbitaceae transformed with a binary plant transformation vector. Stable expression of a reporter gene (GUS) under control of the truncated SVBV promoter was shown in transformed tobacco shoots in roots, leaves and stems.
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  • 21
    ISSN: 1573-5060
    Keywords: Barley ; Hordeum vulgare ; transformation ; particle bombardment ; particle gun
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Immature embryos of the spring barley variety GoldenPromise, were bombarded with three different particledelivery systems and both transient and stabletransformation examined. In addition, a range oftechniques for the preparation of the DNA coated goldparticles was examined. Fertile transgenic barleyplants were obtained using three particle preparationtechniques which differed in the amount of gold andDNA used for each bombardment. However, only one ofthe particle delivery systems, the PDS 1000/He device,appeared to be effective in yielding transformedbarley plants.
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  • 22
    ISSN: 1573-5060
    Keywords: Brassica napus ; fatty acid composition ; tissueculture-induced variation ; transformation-induced variation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The variation obtained in storage fatty acids induced by the procedures of tissue culture and transformation with Agrobacterium tumefaciens was investigated and compared in rapeseed, Brassica napus, cv. Hanna. An increased variation in the fatty acid profiles was noted after tissue culture and transformation compared with plants derived directly from seeds. In the second generation of rapeseed transformants, T2, the content of oleic acid ranged from 39–72%, 12–31% for linoleic acid and 7–16% for linolenic acid. This could be compared with the oleic acid content in the T2 generation of tissue culture-derived plants which ranged between 47–76% and in seed-derived material where oleic acid ranged between 55–69%.In the T3 generation the ranges in transgenic seeds were decreased but still larger than in the seed derived plants. The range in transgenic plants was 49–64% for oleic acid, 20–28% for linoleic acid and 9–18% for linolenic acid. The most extreme individuals, both highest and lowest in the common fatty acids, were found in the group of transformed plants independent of generation. The total lipid content was also affected by the two treatments and seeds with the lowest and highest lipid content were both found among the transformed plants. In conclusion, care should be taken to use proper controls when performing transformation experiments in order to distinguish variation in the fatty acid profiles induced by the transformation procedure and tissue culture treatments from the changes due to transgenic expression.
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  • 23
    ISSN: 1573-6776
    Keywords: Escherichia coli ; genetic engineering ; metal-binding ; OmpC ; protein engineering
    Source: Springer Online Journal Archives 1860-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract The outer membrane protein, OmpC, from Escherichia coli was used to display metal-binding poly-histidine peptides on the surface of this bacterium. SDS-PAGE analysis of outer membrane protein preparations confirmed the expression of the metal-binding epitopes inserted in position 162 of the mature OmpC protein. Display of these epitopes was confirmed by epifluorescence microscopy of cells bound to Ni2+-NTA-agarose beads and metal adsorption experiments. The cells harboring one or two copies of the metal binding epitope were able to adsorb 3 to 6 times more Zn2+ (13.8 μmol g−1 cell), Fe3+ (35.3 μmol g−1 cell), and Ni2+ (9.9 μmol g−1 cell) metallic ions than control cells expressing the wild-type OmpC.
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  • 24
    ISSN: 1573-6776
    Keywords: bioremediation ; genetic engineering ; heavy metal ; hydrogen sulfide ; thiosulfate reductase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract The thiosulfate reductase gene (phsABC) from Salmonella typhimuriumwas expressed in Escherichia coliin order to produce sulfide from inorganic thiosulfate and precipitate metals as metal sulfide complexes. The sulfide-engineered strain removed significant amounts of heavy metals from the medium within 24 h: 99% of zinc up to 500 μM, 99% of lead up to 200 μM, 99% of 100 μM and 91% of 200 μM cadmium. In a mixture of 100 μM each of cadmium, lead, and zinc, the strain removed 99% of the total metals from solution within 10 h. Cadmium was removed first, lead second, and zinc last. These results have important implications for removal of metals from wastewater contaminated with several metals.
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  • 25
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    Journal of agricultural and environmental ethics 12 (2000), S. 319-330 
    ISSN: 1573-322X
    Keywords: biotechnology ; consumer sovereignty ; genetic engineering ; informed consent ; product labeling ; risk communication
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Philosophy
    Notes: Abstract Recently, both consumers and producers ofbiotechnology products have insisted thatcommunication between the two be improved. The formerdemand more democratic participation in the riskassessment process of biotechnology products. Thelatter seek to correct misinformation regardingalleged risks from these products. One way to resolvethese concerns, I argue, is through the use ofbiotechnology labels. Such labeling fosters consumerautonomy and moves toward more participatory decisionmaking, in addition to ensuring that informed consentfrom consumers is maintained. Furthermore, althoughvoluntary biotech-free labeling in lieu of biotechlabels may uphold consumer sovereignty, the latterremains a more effective strategy for achievingethical communication between consumers and producersof biotechnology products.
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  • 26
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    Journal of agricultural and environmental ethics 12 (2000), S. 279-303 
    ISSN: 1573-322X
    Keywords: environment ; genetic engineering ; biotechnology ; pesticides ; agriculture ; pest control ; risks
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Philosophy
    Notes: Abstract Despite the application of 2.5 million tons ofpesticides worldwide, more than 40% of all potentialfood production is lost to insect, weed, and plantpathogen pests prior to harvest. After harvest, anadditional 20% of food is lost to another group ofpests. The use of pesticides for pest control resultsin an estimated 26 million human poisonings, with220,000 fatalities, annually worldwide. In the UnitedStates, the environmental and public health costs forthe recommended use of pesticides total approximately$9 billion/yr. Thus, there is a need for alternativenon-chemical pest controls, and genetic engineering(biotechnology) might help with this need. Diseaseand insect pest resistance to various pests has beenslowly bred into crops for the past 12,000 years;current techniques in biotechnology now offeropportunities to further and more rapidly improve thenon-chemical control of disease and insect pests ofcrops. However, relying on a single factor, like theBacillus thuringiensis toxin that has beeninserted into corn and a few other crops for insectcontrol, leads to various environmental problems,including insect resistance and, in some cases, athreat to beneficial biological control insects andendangered insect species. A major environmental andeconomic cost associated with genetic engineeringapplications in agriculture relates to the use ofherbicide resistant crops (HRC). In general, HRCtechnology results in increased herbicide use but noincrease in crop yields. The heavy use of herbicidesin HRC technology pollutes the environment and canlead to weed control costs for farmers that may be2-fold greater than standard weed control costs. Therefore, pest control with both pesticides andbiotechnology can be improved for effective, safe,economical pest control.
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  • 27
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    Journal of agricultural and environmental ethics 13 (2000), S. 313-327 
    ISSN: 1573-322X
    Keywords: Agri-biotech companies ; agriculture ; biotechnology ; existing technologies ; farmers ; farm crisis ; genetic engineering ; hunger ; poverty ; productivity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Philosophy
    Notes: Abstract The use of genetic engineering inagriculture has been the source of much debate. Todate, arguments have focused most strongly on thepotential human health risks, the flow of geneticmaterial to related species, and ecologicalconsequences. Little attention appears to have beengiven to a more fundamental concern, namely, who willbe the beneficiaries of this technology? Given the prevalence of chronic hunger and thestark economics of farming, it is arguable thatfarmers and the hungry should be the mainbeneficiaries of agricultural research. However, theapplication of genetic engineering appears unlikely tobenefit either of these two groups. This technology islargely controlled by the private sector, and itscontinued development hinges on its profitability.Thus, the only likely beneficiaries of the applicationof genetic engineering in agriculture are companieswith the capacity to use it.
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  • 28
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    Journal of agricultural and environmental ethics 13 (2000), S. 43-51 
    ISSN: 1573-322X
    Keywords: genetic engineering ; inherent value ; moral obligation ; Swiss constitution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Philosophy
    Notes: Abstract The Swiss expert report suggests thatthe inherent dignity of a living being be identifiedwith its inherent value. But the phrase ``inherentvalue of a living being'' seems to connote two conceptsof inherent value. One has a morally obligatingcharacter but is counterintuitive because of itsegalitarianism. The other is one of non-moral value.It is more compatible with considered intuitions butinsufficient for substantiating the expert report'sclaim that human beings have moral duties towardsanimals and plants. The paper discusses theseconcepts. Consideration is then given to the problemof how discursive support can be generated for theexpert report's claim that human beings have the moralduty to abstain from impairing those functions andabilities of a non‐uman being that members of itsspecies as a rule can practice.
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  • 29
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    Journal of agricultural and environmental ethics 13 (2000), S. 29-42 
    ISSN: 1573-322X
    Keywords: dignity of creatures ; genetic engineering ; human dignity ; inherent value ; Swiss Constitution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Philosophy
    Notes: Abstract In their report for the Swiss government onthe notion of the dignity of creatures, PhilippBalzer, Klaus-Peter Rippe, and Peter Schaber analyzethe relationship between human dignity and the dignityof creatures, taking them as two categoricallydifferent concepts. Human dignity is defined as the``moral right not to be humiliated,'' whereas thedignity of creatures is taken to be ``the inherentvalue of non‐human living beings.'' To my mind there isno need to draw a categorical distinction between thetwo concepts. Both notions could be brought togetherunder an all-encompassing concept of the inherentvalue of living beings, humans and non-humans alike,a concept one could name ``the dignity of livingbeings.'' Indeed, this very notion underlies theposition taken in the report, although this is notmade explicit by the authors themselves. As the aim of the paper is only to clarify theconcepts used, I do not go beyond this ``internal''critique of their position, i.e., I don't assess howthe claims articulated via these concepts – theclaim that humans and/or creatures have an inherentvalue consisting in a supposed intrinsic good – areto be justified, although I myself would be ratherskeptical that this might be successfully done.
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  • 30
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    Journal of agricultural and environmental ethics 13 (2000), S. 7-27 
    ISSN: 1573-322X
    Keywords: dignity ; Swiss Constitution ; nonhuman inherent value ; genetic engineering
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Philosophy
    Notes: Abstract The 1992 incorporation of an article by referendum in the SwissConstitution mandating that the federal government issue regulations onthe use of genetic material that take into account the dignity ofnonhuman organism raises philosophical questions about how we shouldunderstand what is meant by ``the dignity of nonhuman animals,'' andabout what sort of moral demands arise from recognizing this dignitywith respect to their genetic engineering. The first step in determiningwhat is meant is to clarify the difference between dignity when appliedto humans and when applied to nonhumans. Several conceptions of humandignity should be rejected in favor of a fourth conception: the rightnot to be degraded. This right implies that those who have it have thecognitive capacities that are prerequisite for self-respect. In the caseof nonhuman organisms that lack this capacity, respecting their dignityrequires the recognition that their inherent value, which is tied totheir abilities to pursue their own good, be respected. This value isnot absolute, as it is in the case of humans, so it does not prohibitbreeding manipulations that make organisms more useful to humans. But itdoes restrict morally how sentient animals can be used. In regard togenetic engineering, this conception requires that animals be allowedthe uninhibited development of species specific functions, a positionshared by Holland and Attfield, as opposed to the Original Purposeconception proposed by Fox and the Integrity of the Genetic Make-upposition proposed by Rolston. The inherent value conception of dignity,as here defended, is what is meant in the Swiss Constitution article.
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  • 31
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    Journal of chemical ecology 26 (2000), S. 2387-2399 
    ISSN: 1573-1561
    Keywords: Rhizopus spp. ; Fusarium spp. ; rhizosphere microorganisms ; Brassicaceae ; Rorippa sylvestris ; Brassica napus ; Brassica juncea ; Lepidium sativum ; myrosinase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract We isolated several strains of Rhizopus and Fusarium spp. as dominant fungi in the rhizospheres of Brassicaceae plants. The Fusarium isolates showed a higher tolerance of the antifungal constituents of "mustard oil," which originates from the glucosinolates that are characteristic secondary metabolites of the Brassicaceae, than other Fusarium isolates from non-Brassicaceae plants. In contrast, the Rhizopus isolates showed a high tolerance regardless of their source. Myrosinase activity was found in Bn-R-1-1 (Rhizopus sp.) isolated from the rhizoplane of Brassica napus and Ls-F-in-4-1 (Fusarium sp.) isolated from a surface-disinfected root of Lepidium sativum (Brassicaceae). Ls-F-in-4-1 was the Fusarium most tolerant of the Brassicaceae antifungal constituents. These results suggest that fungi in the rhizospheres of Brassicaceae plants may be selected because of secondary metabolites exuded from the roots of host plants.
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  • 32
    ISSN: 1573-9368
    Keywords: particle bombardment ; minimal cassette ; cotransformation ; transgenic rice ; integration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Whole plasmids are used in both Agrobacterium-mediated transformation and direct DNA transfer, generally leading to the integration of vector backbone sequences into the host genome along with the transgene(s). This is undesirable, as vector backbone sequences often have negative effects on transgene or endogenous gene expression, and can promote transgene rearrangements. We, therefore, bombarded rice tissue with two constructs: a plasmid containing the bar gene, and a linear DNA fragment isolated from the same plasmid, corresponding to the minimal bar gene expression cassette (promoter, open reading frame and terminator). We recovered phosphinothricin-resistant plants from both experiments, showing that the selectable marker was efficiently expressed. Transformation with such constructs resulted in predominantly 'simple' integration events (one or two bands on Southern blots), producing low-copy-number transgenic plants with a low frequency of transgene rearrangements. Conversely, transformation with supercoiled or linearized whole plasmids generated plants with 'complex' integration patterns, that is, higher copy numbers and frequent transgene rearrangements. We monitored transgenic lines through to the R4 generation and observed no silencing in plants carrying minimal constructs. We also carried out experiments in which rice tissue was simultaneously bombarded with minimal linear hpt and gusA cassettes. We observed robust GUS activity in hygromycin-resistant plants, confirming co-expression of the selectable and nonselectable markers. Furthermore, the efficiency of cotransformation using minimal constructs was the same as that using supercoiled plasmid cointegrate vectors.
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  • 33
    ISSN: 1573-9368
    Keywords: calcium-dependent ; light regulation ; particle bombardment ; protein kinase ; seed development ; transgenic rice
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Independent transgenic rice lines overexpressing the rice CDPK isoform OsCDPK2 were generated by particle bombardment. High levels of OsCDPK2 were detected in leaves removed from etiolated plants, as well as in stems and flowers. However, there was no overexpression in green leaves that had been exposed to light, confirming that OsCDPK2 protein stability was subject to light regulation. The morphological phenotype of transgenic plants producing high levels of recombinant OsCDPK2 was normal until the onset of seed development. Flowers developed normally, producing well-shaped ovaries and stigmas, and mature anthers filled with pollen grains. However, seed formation in these plants was strongly inhibited, with only 3–7% of the flowers producing seeds. Seed development was arrested at an early stage. We discuss these data with respect to the possible requirement for specific CDPK isoforms during rice seed 4.4ptdevelopment.
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  • 34
    ISSN: 1432-203X
    Keywords: Ammonia ; Agrobacterium rhizogenes ; Brassica napus ; glutamine ; glutamine synthetase ; phosphinothricin ; rape
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Hairy roots of Brassica napus (rape cv. Giant) were produced by cocultivating leaf and cotyledon explants with Agrobacterium rhizogenes strain A4T. The hairy roots grew prolifically on solid and in liquid media. Incorporation of ammonium sulphate or phosphinothricin (PPT) into the media reduced growth. PPT treatment reduced glutamine synthetase (GS) activity and increased the ammonia content of the hairy roots. We have found that PPT treatment also induces a loss of glutamine from the roots and this may influence root growth. To test this we grew hairy roots in a liquid medium containing 10 mM glutamine. This glutamine treatment overcame the PPT induced suppression of growth but also significantly increased GS activity, reduced ammonia accumulation and increased the levels of glutamate and asparagine.
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  • 35
    ISSN: 1573-5028
    Keywords: anti-bacterial protein ; genetic engineering ; precursor processing ; synthetic gene ; thionin ; transgenic
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Hordothionins (HTHs) are small anti-bacterial proteins present in barley endosperm which are processed from larger precursor proteins, consisting of an amino-terminal signal peptide (SP), the mature highly basic HTH and a carboxy-terminal acidic peptide (AP). Different HTH precursor proteins were expressed in tobacco to study the effects of the pre-sequences (SP) and pro-sequences (AP) on expression, processing, sorting and biological activity and hence the feasibility of engineering bacterial disease resistance into crops which lack these proteins. Maximum HTH expression levels of approximately 0.7% (11 μmol/kg) of total soluble protein in young tobacco leaves were obtained using a semi-synthetic gene construct encoding a complete chimaeric HTH precursor protein. Tenfold lower HTH expression levels (maximum 1.3 μmol/kg) were obtained using synthetic gene constructs without the AP-coding sequence and no expression was found in plants containing synthetic HTH gene constructs without SP-and AP-coding sequences. In both cases where expression was found, the precursors were apparently correctly processed, although the HTH produced in plants containing a construct without AP sequence appeared to be slightly modified. No effect on plant phenotype was observed. Localization studies indicated that the HTH was in identical fractions of plants expressing the two different precursors, albeit at a different ratio, and was not secreted into the intercellular spaces of leaves or culture medium by protoplasts. Our results indicated that the AP is not involved in sorting and suggested that it might facilitate transport through membranes. The in vitro toxicity of HTH isolated from transgenic tobacco plants expressing the two different precursor proteins for the bacterial plant pathogen Clavibacter michiganensis subsp. michiganensis appeared similar to that of the HTH purified from barley endosperm.
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  • 36
    ISSN: 1573-5028
    Keywords: anther ; antisense RNA ; Brassica napus ; male fertility ; tapetum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract An antisense approach was used to attempt to determine the function of the highly abundant, tapetum-specific A9 transcript in microsporogenesis. A Brassica napus A9 cDNA clone was linked in sense and antisense orientations to the Arabidopsis thaliana A9 promoter and the resulting chimaeric genes introduced into B. napus. A high proportion of the offspring of B. napus antisense A9 plants had very low or undetectable levels of A9 mRNA. However, these plants set seed and had pollen of normal or near normal viability. Therefore, under the conditions studied, the A9 protein appears not to be essential for male fertility in B. napus.
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  • 37
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    Plant molecular biology 24 (1994), S. 223-227 
    ISSN: 1573-5028
    Keywords: Brassica napus ; dehiscence ; dehydrogenase ; pod ; protochlorophyllide reductase ; shatter
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Dehiscence of oilseed rape pods, commonly known as pod shatter, is a process of agronomic importance that results in seed loss causing yield reductions and carry-over of the crop into the following growing season. In an effort to understand the mechanisms underlying this developmental event, the changes in gene expression that accompany pod shatter have been examined with a view to understanding how the process is regulated. In order to achieve this, a cDNA library was constructed using mRNA extracted from the dehiscence zone of developing pods. Differential screening with non-dehiscence zone cDNA led to the isolation of a pod-specific clone, SAC25, with a transcript size of 1100 nucleotide encoding a predicted polypeptide of 34 kDa. The level of SAC25 mRNA accumulation increased during pod development. The sequence shows no significant homology to others within the databases but has two identifiable amino acid motifs, one is an adenine nucleotide binding site for NAD/FAD dehydrogenases and the other is a conserved feature of the ribitol dehydrogenase family. The amino acid sequence has four putative glycosylation sites and contains four cysteine residues. Genomic Southern analysis indicates that SAC25 may be encoded by a single gene or a small gene family. The function of this mRNA is unknown but possible roles in dehiscence and pod development are discussed.
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  • 38
    ISSN: 1573-5028
    Keywords: abscisic acid ; ABA-response element ; bi-directional promoter ; Brassica napus ; oleosin ; seed development
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In Brassica napus, oleosins are expressed at high levels in the seed during the latter stages of embryo development. The cis-acting regulatory properties of an 872 bp promoter fragment of a B. napus oleosin gene were examined by analysis of β-glucuronidase (GUS) expression in transgenic tobacco plants containing an oleosin promoter-GUS transcriptional fusion. The reporter gene was expressed at high levels only in seeds, specifically in embryo and endosperm tissue and regulated throughout seed development. These data demonstrate that oleosin gene transcription is regulated in a tissue-specific and temporally regulated manner and clearly indicate that oleosin protein expression is co-ordinated primarily at the transcriptional level. Oleosin mRNA was shown to be abscisic acid (ABA) inducible and an ABA-response element in the oleosin promoter was shown to be bound by a protein factor in a sequence-specific manner. Sequence analysis of the oleosin promoter has identified several other putative cis-acting sequences which may direct oleosin gene expression. The presence of a large open reading frame in the bottom strand of the oleosin promoter (ORF2) which encodes a polypeptide similar to the ethylene-induced E4 gene of tomato is reported. A PCR-generated DNA probe containing the ORF2 sequence hybridised with a 1.4 kb transcript in total RNA extracts of a variety of tissues, including leaves and germinated seed cotyledons. This finding suggests that the oleosin gene promoter directs transcription in both directions. It is the first report of a bi-directional nuclear gene promoter in plants.
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  • 39
    ISSN: 1573-5028
    Keywords: Brassica napus ; Enoyl-ACP reductase ; isoforms ; stearoyl-ACP desaturase ; developmental expression ; seed
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The expression of mRNA and the steady-state levels of two-component enzymes of plant fatty acid synthetase (FAS) were studied. Northern analysis of enoyl-ACP reductase (ER) and stearoyl-ACP desaturase (SD) gene expression showed that steady-state levels of both transcripts increase during lipid deposition in the seed reaching a maximum at 29 days after flowering (DAF). The steady-state level of ER message falls very quickly after reaching its maximum, whereas the SD message is longer-lived. The levels of these specific mRNAs in seed are 15–30 times greater than in leaf. Optimum mRNA expression precedes the maximum levels of synthesis of the two proteins, which in turn precede the maximum level of oil. The expression of isoenzymes of ER were examined by two-dimensional western blotting in both leaf and seed tissue. Four enzymes are expressed in both of these tissues; the two most abundant isoforms in seed material are also the most abundant in leaf tissue.
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  • 40
    ISSN: 1573-5028
    Keywords: Brassica napus ; napin ; antisense ; seed storage protein ; seed storage lipid
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract To manipulate the quantity and quality of storage components in Brassica napus seeds, we have constructed an antisense gene for the storage protein napin. The antisense gene was driven by the 5′-flanking region of the B. napus napin gene to express antisense RNA in a seed-specific manner. Seeds of transgenic plants with antisense genes often contained reduced amounts of napin. In some transgenic plants, no accumulation of napin was observed. However, the total protein content of transgenic and wild-type seeds did not differ significantly. Seeds lacking napin accumulated 1.4 to 1.5 times more cruciferin than untransformed seeds, although the oleosin content was not affected. Fatty acid content and composition in the seeds of transgenic plants were also analyzed by gas chromatography. Though the total fatty acid content of the transformants was the same as that of non-transformants, there was a reduction in 18:1 contents and a concomitant increase of 18:2 in seeds with reduced napin levels. This observed change in fatty acid composition was inherited in the next generation.
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  • 41
    ISSN: 1573-5028
    Keywords: Brassica napus ; heterologous expression ; Rab/Ypt family ; small GTP-binding protein ; vesicular transport
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A cDNA clone (bra) encoding a small GTP-binding protein was isolated from Brassica napus by screening a root cDNA library with a degenerate oligonucleotide probe that corresponds to a highly conserved GTP-binding domain of the Ras superfamily. Sequence analysis shows that the clone contains an open reading frame of 219 amino acid residues with the estimated molecular mass of 24379 Da and this coding region contains all the conserved motifs of the Ras superfamily. The deduced amino acid sequence of the bra gene is most closely related to the Ypt/Rab family that functions in the vesicular transport (46% and 47% amino acid identity to the yeast Ypt1 and to the human Rab1, respectively) and is more distantly related to the other Ras-related families. The protein encoded by the bra gene, when expressed in Escherichia coli, shows the ability to bind GTP. Furthermore, when the bra gene is introduced into Saccharomyces cerevisiae under the regulation of the yeast GAL1 promoter, the gene can complement the temperature-sensitive yeast mutation ypt1-1 that has defects in vesicular transport function. The amino acid sequence similarity and the functional complementation of the yeast mutation suggest that this gene is likely to be involved in the vesicular transport in plants. Genomic Southern analysis shows that this gene is a member of a small gene family in Brassica napus.
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  • 42
    ISSN: 1573-5028
    Keywords: Arabidopsis thaliana ; Brassica napus ; gene expression ; Nicotiana tabacum ; retrotransposon
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The expression of the tobacco (Nicotiana tabacum) retrotransposon Tntl has previously been shown to be strongly regulated and driven from the 5′ long terminal repeat (LTR). We report here that the Tntl LTR can promote activity of the β-glucuronidase (GUS) reporter gene in two heterologous species of the Brassicaceae family, namely rapessed (Brassica napus) and Arabidopsis thaliana. The translational LTR-GUS fusion was active in transient expression studies performed with tobacco and rapeseed protoplasts, indicating that the LTR sequences are recognized in heterologous species. Our results also showed that Tntl LTR-promoted GUS expression in transgenic Arabidopsis is strongly regulated, and that, in contrast to tobacco, hormonal activation plays a significant role in the expression of the Tntl LTR in Arabidopsis. LTR sequences were shown to be more effective than the CaMV 35S enhancer region in transient expression studies performed with tobacco or rapessed protoplasts; and substitution of the LTR sequences upstream from the major transcriptional start with the CaMV 35S enhancer region gave high levels of expression in transgenic tobacco and Arabidopsis leaves, suggesting that a Tntl element with similar substitutions in its 5′ LTR might be suited for gene-tagging experiments in heterologous species.
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  • 43
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    Plant molecular biology 26 (1994), S. 1217-1222 
    ISSN: 1573-5028
    Keywords: Brassica napus ; pistil ; stigma ; cDNA
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A partial cDNA clone, Pis 63, corresponding to a mRNA highly expressed in Brassica napus pistils, was isolated by differential screening. PCR was used to complete the Pis 63 sequence (Pis 63-1) and to obtain the sequence of another related cDNA (Pis 63-2). Northern blot and in situ analyses demonstrated that these transcripts are expressed in the stigma throughout flower development. Pis 63-1 and Pis 63-2 display similarity to a cotton fibre cDNA clone.
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  • 44
    ISSN: 1573-5028
    Keywords: Antibody ; coordinated expression ; genetic engineering ; protein assembly ; root ; secretion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract To explore the feasibility of employing antibodies to obtain disease resistance against plant root pathogens, we have studied the expression of genes encoding antibodies in roots of transgenic plants. A model monoclonal antibody was used that binds to a fungal cutinase. Heavy and light chain cDNAs were amplified by PCR, fused to a signal sequence for secretion and cloned behind CaMV 35S and TR2′ promoters in a single T-DNA. The chimeric genes were cloned both in tandem and in a divergent orientation. The roots of tobacco plants transformed with these constructs produced antibodies that were able to bind antigen in an ELISA. Immunoblotting showed assembly to a full-size antibody. In addition, a F(ab′)2-like fragment was observed, which is probably formed by proteolytic processing. Both antibody species were properly targeted to the apoplast, but the full-size antibody was partially retained by the wall of suspension cells. The construct with divergent promoters showed a better performance than the construct with promoters in tandem. It directed the accumulation of functional antibodies to a maximum of 1.1% of total soluble protein, with half of the plants having levels higher than 0.35%. The high efficiency of this construct probably results from coordinated and balanced expression of light and heavy chain genes, as evidenced by RNA blot hybridization.
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  • 45
    ISSN: 1573-5028
    Keywords: Brassica napus ; microspore embryogenesis ; napin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Brassica napus cv. Topas microspores can be diverted from pollen development toward haploid embryo formation in culture by subjecting them to a heat stress treatment. We show that this switch in developmental pathways is accompanied by the induction of high levels of napin seed storage protein gene expression. Changes in the plant growth or microspore culture conditions were not by themselves sufficient to induce napin gene expression. Specific members of the napin multigene family were cloned from a cDNA library prepared from microspores that had been induced to undergo embryogenesis. The majority of napin clones represented three members (BnmNAP2, BnmNAP3 and BnmNAP4) that, along with a previously isolated napin genomic clone (BngNAP1), constitute the highly conserved BnmNAP subfamily of napin genes. Both RNA gel blot analysis, using a subfamily-specific probe, and histochemical analysis of transgenic plants expressing a BngNAP1 promoter-β-glucuronidase gene fusion demonstrated that the BnmNAP subfamily is expressed in embryogenic microspores as well as during subsequent stages of microsporic embryo development.
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  • 46
    ISSN: 1573-5028
    Keywords: fertile transgenic barley ; gene transfer ; Hordeum vulgare ; neomycin phosphotransferase II ; particle bombardment
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Transgenic, fertile barley (Hordeum vulgare L.) from the Finnish elite cultivar Kymppi was obtained by particle bombardment of immature embryos. Immature embryos were bombarded to the embryonic axis side and grown to plants without selection. Neomycin phosphotransferase II (NPTII) activity was screened in small plantlets. One out of a total of 227 plants expressed the transferred nptII gene. This plant has until now produced 98 fertile spikes (T0), and four of the 90 T0 spikes analyzed to date contained the nptII gene. These shoots were further analyzed and they expressed the transferred gene. From green grains, embryos were isolated and grown to plantlets (T1). The four transgenic shoots of Toivo (the T0 plant) produced 25 plantlets as T1 progeny. Altogether fifteen of these T1 plants carried the transferred nptII gene as detected with the PCR technique, fourteen of which expressed the nptII gene. The integration and inheritance of the transferred nptII gene was confirmed by Southern blot hybridization. Although present as several copies, the transferred gene was inherited as a single Mendelian locus into the T2 progeny.
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  • 47
    ISSN: 1573-5028
    Keywords: acyl-CoA-binding protein ; Brassica napus ; diazepam-binding inhibitor protein ; linkage map
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A cDNA encoding an acyl-CoA-binding protein (ACBP) homologue has been cloned from a λgt11 library made from mRNA isolated from developing seeds of oilseed rape (Brassica napus L.). The derived amino acid sequence reveals a protein 92 amino acids in length which is highly conserved when compared with ACBP sequences from yeast, cow, man and fruit fly. Southern blot analysis ofBrassica napus genomic DNA revealed the presence of 6 genes, 3 derived from theBrassica rapa parent and 3 fromBrassica oleracea. Northern blot analysis showed that ACBP genes are expressed strongly in developing embryo, flowers and cotyledons of seedlings and to a lesser extent in leaves and roots.
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  • 48
    ISSN: 1432-203X
    Keywords: Agrobacterium rhizogenes ; Brassica napus ; glutamine synthetase ; phosphinothricin ; rape ; transformation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Hairy roots of Brassica napus (rape cv. Giant) have been produced that contain the cytosolic glutamine synthetase (GS) gene from Glycine max (soybean). Leaf explants were cocultivated with Agrobacterium rhizogenes strain A4T harbouring the binary vector pLN16. This vector was constructed by inserting a soybean cytosolic GS cDNA into the multiple cloning site of pGA643, placing it under the control of the CaMV promoter. In addition, the T-DNA region of pLN16 contained a NPTII gene for selection of transformed cells. Transgenic hairy roots grew prolifically on hormone-free media containing a selective level of kanamycin. Southern and northern analyses confirmed the presence of soybean GS DNA and transcripts, respectively. These transformed hairy roots also have a greater abundance of the GS polypeptide, approximately 3–6 fold greater GS activity and lower levels of endogenous ammonia. Hairy roots provide a useful system for studying responses to phosphinothricin (PPT). Hairy roots grown in media containing PPT had lower GS activity, greater ammonia accumulation and slower growth than controls. The presence of the soybean GS gene in the hairy roots reduced these PPT-induced effects and resulted in higher GS activity, lower ammonia levels and faster growth than in PPT-treated controls. Greater tolerance of PPT was also seen in shoots regenerated from the hairy roots displaying elevated levels of GS activity.
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  • 49
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    Theoretical and applied genetics 87 (1994), S. 697-704 
    ISSN: 1432-2242
    Keywords: Brassica napus ; Cultivar identification ; RAPDs ; Rapeseed ; Taxonomy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract RAPDs (Randomly Amplified Polymorphic DNAs) were used to discriminate among 23 cultivars of oilseed rape (Brassica napus) selected from several breeding programs. A set of 100 random sequence 10-mer primers were tested, of which 70 produced bands and 22 showed evidence of polymorphism. A selection of six primers produced 23 polymorphic bands of between 300 to 2200 base pairs in size, sufficient to distinguish between the cultivars. An analysis of seed of five cultivars obtained from four different sites showed stability of banding pattern over source of seed. The analysis was repeated using four different thermocyclers, each of which produced the same band pattern. UPGMA cluster analysis indicates that the relationships among some of the cultivars is closer for those from the same breeding program than for those from different programs. The results of this study show that RAPDs can be used as a method of identification for oilseed rape cultivars.
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  • 50
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    Theoretical and applied genetics 88 (1994), S. 123-128 
    ISSN: 1432-2242
    Keywords: Brassica napus ; RFLP markers ; RAPD markers ; Genetic distance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract RFLP and RAPD markers were evaluated and compared for their ability to determine genetic relationships in a set of three B. napus breeding lines. Using a total of 50 RFLP and 92 RAPD markers, the relatedness between the lines was determined. In total, the RFLP and the RAPD analysis revealed more than 500 and 400 bands, respectively. The relative frequencies of loci with allele differences were estimated from the band data. The RFLP and RAPD marker sets detected very similar relationships among the three lines, consistent with known pedigree data. Bootstrap analyses showed that the use of approximately 30 probes or primers would have been sufficient to achieve these relationships. This indicates that RAPD markers have the same resolving power as RFLP markers when used on exactly the same set of B. napus genotypes. Since RAPD markers are easier and quicker to use, these markers may be preferred in applications where the relationships between closely-related breeding lines are of interest. The use of RAPD markers in fingerprinting applications may, however, not be warranted, and this is discussed in relation to the reliability of RAPD markers.
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  • 51
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    Theoretical and applied genetics 88 (1994), S. 662-668 
    ISSN: 1432-2242
    Keywords: Oilseed rape ; Brassica napus ; Restriction fragment length polymorphism ; Genetic diversity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Oilseed rape (Brassica napus) is an important oilseed crop worldwide. Cultivars have been developed for many growing regions, however little is known about genetic diversity inB. napus germ plasm. The purpose of the research presented here was to study the genetic diversity and relationships ofB. napus accessions using restriction fragment length polymorphisms (RFLPs). Eighty threeB. napus accessions were screened using 43 genomic DNA clones which revealed 161 polymorphic fragments. Each accession was uniquely identified by the markers with the exception of the near-isogenic cvs ‘Triton’ and ‘Tower’. The RFLP data were analyzed by cluster analysis of similarity coefficients and by principal component analysis. Overall, there were three major groups of cultivars. The first group included only spring accessions, the second mostly winter accessions and the third, rutabagas and oilseed rape accessions from China and Japan. These results indicate that withinB. napus, winter and spring cultivars represent genetically distinct groups. The grouping of accessions by cluster analysis was generally consistent with known pedigrees. This consistency included the grouping of lines derived both by backcrossing or self-pollination with their parents.
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  • 52
    ISSN: 1432-2242
    Keywords: Brassica napus ; Raphanus sativus ; Ogura cytoplasmic male-sterility restorer gene ; Bulked segregant analysis ; RAPD markers
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Bulked segregant analysis was employed to identify random amplified polymorphic DNA (RAPD) markers linked to the restorer gene (Rfo) used in theOgura radish cytoplasmic male sterility of rapeseed. A total of 138 arbitrary 10-mer oligonucleotide primers were screened on the DNA of three pairs of bulks, each bulk corresponding to homozygous restored and male sterile plants of three segregating populations. Six primers produced repeatable polymorphisms between paired bulks. DNA from individual plants of each bulk was then used as a template for amplification with these six primers. DNA polymorphisms generated by four of these primers were found to be completely linked to the restorer gene with the polymorphic DNA fragments being associated either with the fertility restorer allele or with the sterility maintainer allele. Pairwise cross-hybridization demonstrated that the four polymorphic DNA fragments did not share any homology. Southern hybridization of labelled RAPD fragments on digested genomic DNA from the same three pairs of bulks revealed fragments specific to either the male sterile bulks or to the restored bulks and a few fragments common to all bulks, indicating that the amplified sequences are low copy. The four RAPD fragments that were completely linked to the restorer locus have been cloned and sequenced to develop sequence characterized amplified regions (SCARs). This will facilitate the construction of restorer lines used in breeding programs and is the first step towards map-based cloning of the fertility restorer allele.
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  • 53
    ISSN: 1432-2242
    Keywords: Polymerase chain reaction ; Random amplified polymorphic DNA ; Self-incompatibility ; Brassica campestris ; Brassica napus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We have developed an efficient PCR-based system that uses RAPD markers for the certification of F1 hybrids of canola. These markers were selected by screening five parental lines used in three crosses X, Y and Z with 131, 131 and 322 primers respectively. Stable DNA fragments that were homozygous and specific to the male inbreds were used to certify F1 hybrid populations. The hybrid production system was based on self-incompatibility (SI) alleles that prevent self-pollination of the female parent. The efficiency of two S-alleles was compared under both field and greenhouse conditions. The percentage of hybridity was estimated in different F1 populations. We found a significant difference between the two alleles for their efficiency in controlling selfing; both alleles were stable under greenhouse conditions, one allele appeared less reliable under field conditions.
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  • 54
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    Theoretical and applied genetics 89 (1994), S. 615-621 
    ISSN: 1432-2242
    Keywords: Brassica napus ; Doubled haploid ; Linkage map ; Restriction fragment length polymorphism
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The combined use of doubled haploid lines and molecular markers can provide new genetic information for use in breeding programs. An F1-derived doubled haploid (DH) population of Brassica napus obtained from a cross between an annual canola cultivar (‘Stellar’) and a biennial rapeseed (‘Major’) was used to construct a linkage map of 132 restriction fragment length polymorphism loci. The marker loci were arranged into 22 linkage groups and six pairs of linked loci covering 1016 cM. The DH map was compared to a partial map constructed with a common set of markers for an F2 population derived from the same F1 plant, and the overall maps were not significantly different. Comparisons of maps in Brassica species suggest that less recombination occurs in B. napus (n = 19) than expected from the combined map distances of the two hypothesized diploid progenitors, B. oleracea (n = 9) and B. rapa (n=10). A high percentage (32%) of segregating marker loci were duplicated in the DH map, and conserved linkage arrangements of some duplicated loci indicated possible intergenome homoeology in the amphidiploid or intragenome duplications from the diploid progenitors. Deviation from Mendelian segregation ratios (P 〈 0.05) was observed for 30% of the marker loci in the DH population and for 24% in the F2 population. Deviation towards each parent occurred at equal frequencies in both populations and marker loci that showed deviation clustered in specific linkage groups. The DH lines and molecular marker map generated for this study can be used to map loci for agronomic traits segregating in this population.
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  • 55
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    Theoretical and applied genetics 88 (1994), S. 321-323 
    ISSN: 1432-2242
    Keywords: Brassica napus ; Inbreeding ; Inbreeding depression ; Line variation ; Competition
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Rapeseed plants, of the summer annual variety Topas, that had been selfed twice consecutively were compared to outcrossed half-sibs for inbreeding depression in a rapeseed population at mating equilibrium. The effect of dominance-suppression competition was included in the effect of inbreeding. Both female-and male-fitness characters showed significant inbreeding depression. Biomass decreased 17% with inbreeding and was highly correlated with seed weight. The total number of flowers decreased 15% with inbreeding. There was a significant effect of lines. The possible importance of experimental design in studies that estimate inbreeding depression is discussed.
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  • 56
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    Theoretical and applied genetics 89 (1994), S. 540-544 
    ISSN: 1432-2242
    Keywords: Brassica napus ; Crossability ; Cytogenetics ; Intergeneric hybridization ; Sinapis pubescens
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The cytological possibility of gene transfer from Sinapis pubescens to Brassica napus was investigated. Intergeneric hybrids between Brassica napus (2n = 38) and Sinapis pubescens (2n = 18) were produced through ovary culture. The F1 hybrids were dihaploid and the chromosome configurations were (0–1) III + (2–11) II + (5–24) I . One F2 plant with 38 chromosomes was obtained from open pollination of the F1 hybrid. Thirty-one seeds were obtained from the backcross of the F2 plant with B. napus. Five out of seven plants had 38 chromosomes, and the pollen stainability ranged from 0% to 81.4%. In the B2 plants obtained from the backcross of B1 plants with B. napus, 66.7% of the plants examined had 38 chromosomes. S. pubescens may become a gene source for the improvement of B. napus.
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  • 57
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    Transgenic research 3 (1994), S. 263-278 
    ISSN: 1573-9368
    Keywords: Brassica napus ; oilseed rape ; transgenic plants ; interspecific hybridization ; gene transfer ; risk assessment
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Before novel transgenic plant genotypes are grown outside containment facilities and evaluated under field conditions, it is necessary to complete a risk assessment to consider the possible consequences of that release. An important aspect of risk assessment is to consider the likelihood and consequences of the transgene being transferred by cross-pollination to related species, including other crops, weeds and ruderal populations. The purpose of this report is to review the literature to assess the ease with whichBrassica napus can hybridize with related species. The evidence for hybridization is considered at three levels: a) by open pollination, b) by hand pollination and c) by the use ofin vitro ovule and embryo rescue techniques; and also examines the fertility and vigour of the F1, F2 and backcross generations. Four species are reported to hybridize withB. napus by open pollination:B. rapa andB. juncea using fully fertile parents; andB. adpressa andR. raphanistrum using a male-sterileB. napus parent. Seventeen species are reported to form hybrids (including the four species above) withB. napus when pollination is carried out manually. At least 12 of these species were unable to form F2 progeny, and eight were unable to produce progeny when the F1 was backcrossed to one of the parental species. Many factors will influence the success of hybridization under field conditions, including: distance between the parents, synchrony of flowering, method of pollen spread, specific parental genotypes used, direction of the cross and the environmental conditions. Even where there is a possibility of hybridization betweenB. napus and a related species growing in the vicinity of a release, poor vigour and high sterility in the hybrids will generally mean that hybrids and their progeny will not survive in either an agricultural or natural habitat.
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  • 58
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    Protoplasma 183 (1994), S. 67-76 
    ISSN: 1615-6102
    Keywords: Actin microfilaments ; Brassica napus ; Cytochalasin D ; Pollen development
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The organization of actin microfilaments (MFs) was studied during pollen development ofBrassica napus cv. Topas. Cells were prepared using three techniques and double labelled for fluorescence microscopy with rhodamine-labelled phalloidin for MFs and Hoechst 33258 for DNA. Microfilaments are present at all stages of pollen development with the exception of tricellular pollen just prior to anthesis. Unicellular microspores contain MFs which radiate from the surface of the nuclear envelope into the cytoplasm. During mitosis MFs form a network partially surrounding the mitotic apparatus and extend into the cytoplasm. Both cytoplasmic and phragmoplast-associated MFs are present during cytokinesis. Nuclear associated-, cytoplasmic, and randomly oriented cortical MFs appear in the vegetative cell of the bicellular microspore. Cortical MFs in the vegetative cell organize into parallel MF bundles (MFBs) aligned transverse to the furrows. The MFBs disappear prior to microspore elongation. At anthesis MFs are restricted to the cortical areas subjacent to the furrows of the vegetative cell. The use of cytochalasin D to disrupt MF function resulted in: (1) displacement of the acentric nucleus in the unicellular microspore; (2) displacement of the spindle apparatus in the mitotic cell; (3) symmetrical growth of the bicellular microspore rather than elongation and (4) inhibition of pollen tube germination in the mature pollen grain. This suggests that MFs play an important role in anchoring the nucleus in the unicellular microspore as well as the spindle apparatus during microspore mitosis, in microspore shape determination and in pollen tube germination.
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  • 59
    ISSN: 1573-5060
    Keywords: Brassica napus ; light reflectance ; seed colour ; NIR
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Improved oil, protein and fibre contents are associated with light seed colour in rapeseed but the lack of reliable and efficient methods to measure seed colour has hindered breeding efforts for this trait. The feasibility of using light reflectance to assess seed colour in Brassica napus was examined using scanning light reflectance spectrophotometry and near infrared reflectance (NIR). Light reflectance by seed samples from 30 doubled haploid (DH) lines segregating for seed colour increased as the wavelength of the illuminating light in the scanning spectrophotometer increased between 550 and 650 nm. The largest reflectance values were measured for the yellow seed samples; the brown seed samples were intermediate and the black seed samples had the lowest reflectance values. The areas under the reflectance curves were used to transform the spectra to single values. Average light reflectance area values for the seed colour classes were significantly different from each other. The DHs and their corresponding light reflectance area values were also used to calibrate a NIR analyzer modified with 670 and 710 nm filters. The best calibration curve used three wavelengths (670, 2190 and 2208 nm) and had a multiple correlation coefficient of 0.987. Light reflectance area values determined with the calibrated NIR analyzer for 30 randomly selected breeding lines could be used to categorize the colour of the seed samples with no discrepancies between the visual and instrument classifications. The results indicate that NIR can be used to assess seed colour in rapeseed.
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  • 60
    ISSN: 1573-5087
    Keywords: abscisic acid ; 1-aminocyclopropane-1-carboxylic acid ; BAS 111..W ; Brassica napus ; cytokinins ; oilseed rape ; pod ; senescence ; triazole growth retardant
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Foliar treatment of oilseed rape plants (Brassica napus L.ssp. napus cv. Linetta) with the growth retardant BAS 111..W at the 5th leaf stage delayed pod senescence during early maturation. Changes of immunoreactive cytokinin- and abscisic acid (ABA)- like substances and of the ethylene precursor 1-aminocyclo-propane-1-carboxylic acid (ACC) and its malonyl-conjugate (MACC) were determined in intact whole pods. When compared with control plants, higher levels of total chlorophyll correlated with four-fold and three-fold increases of trans-zeatin riboside- and dihydrozeatin riboside-type cytokinins, respectively, in the pods of plants treated with 0.25 mg BAS 111..W per plant. Isopentenyladenosine-type cytokinins and ACC and MACC contents remained virtually unchanged, whereas ABA levels dropped considerably below those of controls (60% reduction). However, when analysed at late pod maturity, BAS 111..W treatment no longer affected the total chlorophyll content, or the levels of cytokinins, ABA, ACC and MACC. We hypothesize that the retardant-induced changes in the hormonal status of the pods, favouring the senescence-delaying cytokinins as opposed to abscisic acid, could contribute to the developmental delay.
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  • 61
    ISSN: 1573-5060
    Keywords: Brassica napus ; heterosis ; hybrid breeding ; oilseed rape ; self-incompatibility ; pollination control
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Self-incompatibility was shown to be an effective method of pollination control in spring rapeseed (B. napus L. ssp. oleifera (Metzg.)) by comparing the yield of a Westar-Topas syn-1 produced by crossing two SI lines with the yield of the corresponding syn-1 produced by hand pollination. Although the trial showed high-parent heterosis in the syn-1s, there was insufficient replication to determine the level of heterosis.
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  • 62
    ISSN: 1573-5060
    Keywords: Brassica napus ; microspore culture ; colchicine treatment ; chromosome doubling ; DH-breeding
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The effect of colchicine on isolated microspore cultures of Brassica napus was evaluated in order to combine a positive effect of colchicine on the induction of embryogenesis with the possibility to induce chromosome doubling at an early developmental stage, thus avoiding the production of haploid or chimeric plants. Colchicine was added to the culture medium immediately after isolation of B. napus microspores. The cultures were incubated from 6 to 72 h with various concentrations of colchicine. Samples were taken from the regenerating embryoids after 6 weeks for ploidy determination by flow-cytometry. The highest diploidization rate was obtained after a 24 h treatment of microspores with 50 mg/l colchicine, leading to 80–90% diploid embroids. A concentration of 100 mg/l colchicine applied for the same duration resulted in a lower diploidization rate (76–80%). Treatment durations of 6 h were not long enough to induce a high rate of diploidization, whereas the application of 10 mg/l for 72 h was also very effective. A sample of the plants regenerated from the colchicine treated microspores was transferred to the greenhouse. The plants looked similar to normal diploid rapeseed plants and showed reasonable pod and seed set. Thus, an additional generation for seed increase in the greenhouse is rendered unnecessary. The advantage of applying a minimum volume of colchicine under controlled in vitro conditions means a considerable saving of time and labour in DH-breeding programs.
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  • 63
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: β-Nitrostyrene derivatives of adenosine 5′-glutarates are potent and selective bisubstrate-type inhibitors of the epidermal growth factor receptor protein tyrosine kinase (EGF-R PTK). In an attempt to improve the inhibitory activity, this type of compounds was modified with alkyl spacers of varying length between the nitrostyrene and the glutaryl units. The spacers consisted of 1, 3, 4, and 5 atoms to give compounds of the benzyl, oxyethyl, oxypropyl, and oxybutyl series, respectively (Schemes 1 and 2). Adenosine 5′-esters were prepared in the benzyl and oxypropyl series only. Compared to the compounds in the parent series without spacer (IC50 = 0.7-12 μM), most of the modified compounds inhibited the EGF-R PTK only marginally or were inactive (IC50 ≥ 100 μM). The only exceptions were the free acids 19 and 20 with IC50 values of ca. 5 μM. It is noteworthy that esterification of these two hydrogen glutarates with either MeOH or adenosine yielded inactive compounds, which is in contrast to the corresponding substances without spacers.
    Additional Material: 1 Ill.
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  • 64
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthesis and Characterization of the Furo and Thieno Analogues of the Triester of PQQWe report here the synthesis and properties of the furo and thieno analogues of 4,5-dihydro-4,5-dioxo-1H-pyrrolo[2,3-f]quinoline-2,7,9- tricarboxylic acid ( = PQQ), i.e. the furo- and thieno[2,3-f]quinoline-4,5-quinone (FQQ and TQQ, resp.) derivatives B and C, obtained as triesters. The triester of PQQ derivative A is much more stable than the triesters of B or C, and only the triester of A shows strong activity in nonenzymatic catalytic oxidations.
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  • 65
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    Helvetica Chimica Acta 77 (1994), S. 171-181 
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The conversion of the conformation of cyclosporin A (CsA) observed in CHCl3 to the receptor-bound state is investigated by two molecular-mechanics methods, template forcing and dynamic forcing. The conformations of CsA in CHCl3 and complexed with LiCl in THF as determined by NMR are used as starting structures. The transition starting from the CsA/CHCl3-derived conformation is hindered by steric interactions of two side chains (MeBmt1 and Val5). While starting with the CsA/LiCl-derived conformation, the conversion is facile. It is illustrated that these calculations, which are of artificial character, using only the starting and final structures of the observed conformational transition during the receptor-binding event, allow an insight into the interactions between the substrates and receptor in terms of an induced fit.
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    Helvetica Chimica Acta 77 (1994), S. 231-242 
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The transfer properties of the ionic species involved in the Williamson ether synthesis by phase-transfer catalysis were investigated using electrochemical techniques developed for the study of polarised liquid/liquid interfaces. This approach allows the measurement of the apparent partition coefficients of the transferring species. From these data, it is proposed that the role of the phase-transfer catalyst salt in the reaction mechanism is to establish a Galvani distribution potential difference between the two phases which in turn acts as the driving force for transferring the reactive aqueous ions to the organic phase.
    Additional Material: 5 Ill.
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  • 67
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The (R)- and (S)-5-(hydroxymethyl)-3-isopropyloxazolidin-2-ones, ((R)- and (S)-2, resp.), pivotal intermediates in the preparation of optically active β-blockers, were synthesized using (R,E)-2-hydroxypent-3-enenitrile (1) as the chiral starting material. In the synthesis of (R)-2, a known cyclization/inversion step was applied.
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  • 68
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Solutions (2 ml) of small linear and cyclic peptides (4-11), of a peptolide containing nine amino acids and a lactate moiety (12), of the cyclic undecapeptide cyclosporin A (CS, 1), and of the macrolides ascomycin, fujimycin, and rapamycin (13-15) in THF were added to excess LiCl, LiBr, or LiClO4 (up to 3000 equiv. in 40 ml THF) in a calorimeter (calorimetric titration). The enthalpies of interaction measured are in the range of ΔH = -8 to -37 kcal/mol. A similar experiment was carried out with one of the binding proteins of cyclosporin, the human cyclophilin A, to give the thermodynamic parameters for the complexation ΔH = -16, ΔG° = -10 kcal/mol, and ΔS° = -20 cal/mol·deg. at 25° which corresponds to an equilibrium constant K = 2·107 l/mol, in good agreement with the result of independent measurements using different methods. NMR Measurements of the macrolides in (D8)THF containing LiCl show strong down-field shifts of signals of the H-atoms next to C=O and C-OH groups in these molecules.
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  • 69
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The 17O-NMR signals of four true C-nitroso compounds 1-4 appear at particularly low field (1550-1265 ppm), whereas the dimers (azodioxy type) resonate at ca. 400 ppm and the ‘isonitroso compounds’ ( = quinone-oximes; 5 and 6) at ca. 250 ppm. S-Nitroso compounds ( = thionitrites; 8 and 9) show shift values of ca. 1300 ppm, not far from C - NO; the NO+ ion is much stronger shielded (474 ppm). The results, together with those for higher-shielded nitroso compounds X - NO (X = RO, R2N, Cl, O-) are discussed in terms of (a) resonance stabilization through n-donation from X(π-bond order, approximated by the known barriers of rotation around the X - N bond) and of (b) electronic excitation energies ΔE. The latter are approximated by long-wave (symmetry-forbidden) UV/VIS absorptions and confirmed, where available, by the maxima of the curves of circular dichroism (CD); the CD curve of thionitrite 9 has been measured. It is found that the δ(17O) values of X - NO depend both on bond order and on ΔE, which could not be separated. The higher shielding of NO+ compared with X - N=O is explained on the basis of anisotropy effects, which differ between sp and sp2 systems.
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  • 70
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    Helvetica Chimica Acta 77 (1994) 
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 71
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: (1S,2R,6R,7R)-4-Phenyl-3,10-dioxa-5-azatricyclo[5.2.1.02,6]dec-4-en-9-one ((+)-5) obtained in 6 steps from the Diels-Alder adduct of furan to 1-cyanovinyl (1S)-camphanate ((+)-3) was reduced to the corresponding endo-alcohol (-)-6 the treatment of which with HBr/AcOH provided (-)-(3aS,4S,6R,7S,7aR)-4β-bromo-3aβ,4,5,6,7,7aβ-hexahydro-2-phenyl-1,3-benzoxazole-6β,7α-diyl diacetate ((-)-17). Elimination of HBr with 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) and acidic hydrolysis furnished (-)-(1R,2S,3R,4R)-4-aminocyclohex-5-ene-1,2,3-triol ( = (-)-conduramine C1;(-)-1).
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  • 72
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    Helvetica Chimica Acta 77 (1994), S. 10-22 
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 2′-5′ Adenylate trimers 41-44 carrying the (tert-butyl)dimethylsilyl (tbds) group at the 3′-OH position of various sugar moieties were synthesized via the phosphoramidite method. The use of the (tert-butyloxy)carbonyl (boc) and 2-(4-nitrophenyl)ethylsulfonyl (npes) groups for 2′-OH protection in neighbourhood to the 3′-O-tbds residue was compared during the synthesis of the target trimers. For other functional positions, the use of the 2-(4-nitrophenyl)ethyl (npe) and 2-(4-nitrophenyl)ethoxycarbonyl (npeoc) blocking groups were favoured.
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  • 73
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A new and generally applicable synthetic path for the preparation of heteroditopic bis-macrocycles using tri-N-protected tetraazacycloalkanes as building blocks and bromoacetyl bromide as bridging reagent is described. In the first step, bromoacetyl bromide is used as acylating agent for one of the macrocycles, whereas in the second step it is used as alkylating agent for the second macrocycle, thus giving protected bis-macrocyclic amides (e.g. 6). After reduction of the amide moiety and deprotection, bis-azamacrocycles with an ethylene bridge are obtained (e.g. 8). The corresponding homoditopic bis-macrocycles 16 and 17 are also prepared for comparison purpose. Spectrophotometric studies indicate that bis-macrocycle 8, which consists of a 12- and a 14-membered ring, binds two metal ions with equal affinity, whereas compound 13, in which an unsubstituted (cyclam) and a trimethyl-substituted tetraazacyclotetradecane unit (Me3cyclam) are bridged, shows selective metal-ion binding. The first metal ion is always incorporated into the cyclam unit, whereas the second one binds to the Me3cyclam macrocycle. Thus, by sequential addition of two different metal ions, heterobinuclear complexes can easily be prepared. The electrochemistry of the binuclear Ni2+ complexes, studied by CV and DPV, as well as the EPR spectra of the binuclear Cu2+ complexes clearly indicate metal-metal interactions.
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  • 74
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Flash-vacuum thermolysis of the four diastereoisomeric 5,6-epoxy-5,6-dihydro-caryophyllenes 1-4 at 500-550°/0.1-0.7 Torr leads to the hitherto unreported enantiomers of (6RS,7RS)- and (6RS,7SR)-6,7-epoxy-6,7-dihydro-β-farnesenes ((±)-5 and (±)-6, resp.). In particular, (+)-5 is formed in 45% yield (ca. 90% ee) and is, thus, an attractive chiral building block for natural-product synthesis.
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  • 75
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A series of ceramides, called oceanapins A-F (2-7), which are unique for branching at both the sphingosine and fatty-acid chains, have been isolated as pure compounds from the haplosclerid sponge Oceanapia cf. tenuis of the Coral Sea. Following acid hydrolysis, both the fatty-acid and the sphingosine portions were obtained separately, which allowed their unequivocal structural definition. The absolute configuration was secured via protection of C(1′)-OH and Mosher's esterification at C(3′)-OH of the oceanapins.
    Additional Material: 1 Tab.
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  • 76
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The one-electron transfer to large π-delocalized hydrocarbons provides an interesting possibility to crystallize solvent-separated ion-pair salts containing optimally solvated cations. Accordingly, the reduction of 9,10-diphenylanthracene in aprotic THF solution at a sodium metal mirror allows to grow dark-blue prismatic crystals of its radical anion and sixfold THF-solvated sodium cation. The structure of the radical anion is very similar to that recently published for the neutral molecule. According to AM1 hypersurface calculations based on the structural data, the phenyl twist angles obviously must be determined by lattice packing, and the negative charge is delocalized predominantly within the anthracene π system. The counter cation [Na⊕(THF)6], reported ordered for the first time, shows nearly octahedral coordination within a rather densily packed solvent shell. Due to the strong repulsions between the solvent molecules, its isodesmically calculated solvation enthalpy is smaller than that of the analogous dimethoxyethane complex [Na⊕(DME)3].
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  • 77
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    Helvetica Chimica Acta 77 (1994), S. 86-91 
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 14N- and 1H-Coupling constants, determined by ESR, ENDOR, and general-TRIPLE-resonance spectroscopy, are reported for the radical cations of tetrazinodi(heteroarenes) 1-8. The results comply with the expectation that donor properties of these compounds are mainly due to the electron-rich dihydrotetrazine ring.
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  • 78
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    Helvetica Chimica Acta 77 (1994), S. 70-85 
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The biphenyl-containing pseudo-amino acids 2′-(aminomethyl)biphenyl-2-carboxylic acid (Abc; 1) and 2′-(aminomethyl)biphenyl-2-acetic acid (Aba; 2) are used as rigid spacers in the backbone of the cyclic peptides cyclo (-Abc-Ala-Phe-Gly-)2 (5), cyclo(-Abc-Ala-Val-Gly-)2 (6), cyclo(-Aba-Gly-Phe-Ala-)2 (7), and cyclo(-Aba-Ala-Phe-Gly-)2(8). Three different interconverting diastereoisomers are found in solutions of each of these cyclopeptides due to the atropisomerism of the biphenyl units. NMR Techniques and molecular-dynamics calculations allow to conclude that the major diastereoisomer of 5 (and 6) in (D6)DMSO adopts a β-sheet conformation. It is proposed that the pseudo-amino acid 1 of (R)-chirality forms, with attached L-amino acids, a H-bonding pattern comparable to a β-turn (see D in Fig. 4 and F).
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  • 79
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    Helvetica Chimica Acta 77 (1994), S. 92-99 
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Vitamin-B12-Catalyzed C, C-Bond Formation: Synthesis of Jasmonates via Sequential Radical ReactionThe Cbl-catalyzed electroreduction of 3-(2′-bromo-1′-ethoxyethoxy)cyclopenten (1a) in presence of 1-cyanovinyl-acetate (8) gave, in a sequential radical reaction (5-exo-trig-cyclization of 1a followed by addition to 8), 1-cyano-2-(2′-ethoxy-hexahydro-2′H-cyclopenta[b] furan-4′-yl)ethyl acetate (10a). This intermediate was transformed to methyl jasmonate (7; four steps) and epituberolide (9; three steps) in 20 and 31% yield, respectively, from cyclopent-2-en-l-ol.
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  • 80
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    Helvetica Chimica Acta 77 (1994), S. 111-120 
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The Synthesis of Azaisomers of the Triester of PQQ: 3H-Pyrrolo[3,2-f]-, 1H-Pyrrolo[3,2-h]-, and 7H-Pyrrolo[2,3-h]quinolinequinone DerivativesWe describe here the synthesis of the title compounds 3-5, starting from highly substituted aminoindoles. The annelated pyridine rings were built up in each case with dimethyl 4-oxoglutaconate according to Corey's procedure. All three o-quinone derivatives 3-5 are stable compounds, comparable to PQQ-triester. The azaisomers vary in biological activity from practically inactive to strong inhibition of the α-amidating enzyme or the ornithin decarboxylase.
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  • 81
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    Helvetica Chimica Acta 77 (1994), S. 608-614 
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The reaction of 2-(1-phenylvinyl)aniline and 4-chloro-2-(1-phenylvinyl)aniline with acetophenone derivatives, 1-(naphthalen-1-yl)ethanone and 1-(furan-2-yl)ethanone in toluene at 110-115° with toluene-4-sulfonic acid as a catalyst leads in good-to-excellent yields to the 2,2-disubstituted 1,2-dihydro-4-phenyl-quinolines 1-18 (Scheme 1, Table). The structure of the new racemic 1,2-dihydroquinolines 1-18 is determined by NMR spectroscopy. A reaction mechanism proceeding via a 6π-electrocyclic rearrangement of 2-(1-phenylvinyl)anils 19 as the key step is proposed for the formation of these compounds (Scheme 1). The scope and limitations of the novel methods are discussed (Scheme 2).
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  • 82
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    Helvetica Chimica Acta 77 (1994), S. 622-630 
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The 2′-deoxyisoguanosine (1) was synthesized by a two-step procedure from 2′-deoxyguanosine (5). Amination of silylated 2′-deoxyguanosine yielded 2-amino-2′-deoxyadenosine (6) which was subjected to selective deamination of the 2-NH2 group resulting in compound 1. Also 2′,3′-dideoxyisoguanosine (2) was prepared employing the photo-substitution of the 2-substituent of 2-chloro-2′,3′-dideoxyadenosine (4). The latter was synthesized by Barton deoxygenation from 2-chloro-2′-deoxyadenosine (3) or via glycosylation of 2,6-dichloropurine (12) with the lactol 13. Compound 1 was less stable at the N-glycosylic bond than 2′-deoxyguanosine (5). The dideoxynucleoside 2 was deaminated by adenosine deaminase affording 2′,3′-dideoxyxanthosine (17).
    Additional Material: 1 Ill.
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  • 83
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A crude hydrate 6 and a crystalline hemiacetal 7 of glyoxylamide 4 were prepared from crotonamide 5 (Scheme 2). Particularly hemiacetal 7, but also 6 and the ‘dimer’ 8 (obtained from 7) may serve as homochiral auxiliaries. The structure of 8 was determined by X-ray analysis. By arenesulfonyl halides, tryptimines 12-14 of 4 were diastereoselectively transformed into spirotricycles 15-17 and 19.
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  • 84
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A series of 2′-benzamido-2′-deoxyadenosine analogues were synthesized in an effort to find new lead structures for the treatment of sleeping sickness. The 2′-deoxy-2′-(3-methoxybenzamido)adenosine (1h) was proved to be a selective inhibitor of the parasite glyceraldehyde 3-phosphate dehydrogenase which confirms the modeling studies. The solution-state conformation of 2′-(thiophene-2-carboxamido) analogue 1d demonstrates a 2′-endo conformation, an orientation of the thiophene ring under the ribose moiety, and the base part occupying a ‘syn’/‘anti’ equilibrium.
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  • 85
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    Helvetica Chimica Acta 77 (1994), S. 645-654 
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The decomposition of cyclohexyl diazoacetate (5a) in the presence of the chiral [Rh2{(2S)-mepy}4] catalyst leads to a 3:1 cis/trans mixture of bicyclic lactone 6a with an enantiomeric excess of 95-97% (cis) and 90% (trans). The conformationally rigid tert-butyl derivatives 5b and 5c afford, in the presence of the same catalyst, 6b and 6c, respectively, via insertion into the equatorial C—H bonds exclusively, with ee's of ca. 95%. A remarkable degree of induction (92-95%) results in the lactone 6g upon decomposition of 1-isopropyl-2-methylpropyl diazoacetate (5g). The diazoacetates derived from 1-methylcyclohexanol, cyclopentanol and 1-methylcyclopentanol (5d-f) afford under similar conditions insertion products with higher diastereoselectivity, but significantly lower enantioselectivity. Other dirhodium catalysts are less efficient.
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  • 86
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    Helvetica Chimica Acta 77 (1994), S. 661-667 
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The first synthesis of (Z)-neomanoalide (4) and an improved synthesis of its (E)-isomer 3 was accomplished in a concise, regiocontrolled manner by exploiting 2-[(tert-butyl)dimethylsiloxy]-4{[(tert-butyl)dimethylsiloxy]-methyl}furan (6) as the key reagent. Lithiation of 6 and subsequent reaction with the (2Z)- or (2E)-isomer of (6E)-3-{[(tert-butyl)dimethylsiloxy]methyl}-7-methyl-9-(2′,6′,6′-trimethylcyclohex-1′-enyl)nona-2,6-dienyl bromide (5), followed by hydrolysis, afforded the corresponding neomanoalide.
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  • 87
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The 2,4-bis-functionalized phenol 1 is dehydrogenated regioselectivity with potassium ferricyanide, affording the corresponding p-quinonemethide 2. Hydrolysis of 2 affords a mixture of dithioacetal 5a and benzaldehyde 6; 1,6-addition of thiols to 2 gives the dithioacetals 5 of benzaldehyde 6; reaction of 2 with 2,2′-azobis(isobutyronitrile) (= 2,2′-dimethyl-2,2′-azobis(propanenitrile)) leads to 9a, 9b, and 10, addition products of the 1-cyano-1-methylethyl radical. The structures of all products are confirmed mainly by 1H- and 13C-NMR spectroscopy, and the mode of their formation is discussed.
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  • 88
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The conformational space of the trisaccharide α-L-Fuc-(1→2)-β- D-Gal-(1→3)-β -D-GalNAc-1-OPr (2) and of its component disaccharide moieties α -L-Fuc-(1→2)-β -D-Gal-1-OMe (3) and β -D-Gal-(1→3)-β- D-GalNAc-1-OPr (4) was investigated with the aid of molecular-mechanics energy minimizations and molecular-dynamics simulations. These calculations suggested the occurrence of two conformations for each compound characterized by different φ and Ψ glycosidic angles. However, 1H-NMR investigation of D2O solutions of 2-4 indicated a sure preference for one of the two conformers with a contribution of the other one ranging from negligible to low.
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  • 89
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The synthesis on solid phase of a new derivative of the anticoagulant protein hirudin is described (see Scheme and Fig.1, I). The henicosapeptide is a bivalent conjugate of the C-terminus of hirudin and of the active-site-binding tetrapeptide D-Phe-Pro-Arg-Pro linked via a tetraglycine spacer. The peptide, for which the name hirufos was coined, incorporates a stable phosphono derivative of L-phenylalanine which, combined with the other structural modifications, leads to a potent anticoagulant agent. Synthesis was readily achieved by the (9H-fluoren-9-yl)-methoxycarbonyl (Fmoc) strategy followed by acidolytic cleavage from the resin and deprotection, including the liberation of the crucial phosphonic group on L-phenylalanine.
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  • 90
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    Helvetica Chimica Acta 77 (1994), S. 691-708 
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Tri-o-thymotide (TOT) clathrates are enantiomorphous and enantioselective (chiral cages). It was shown that an external molecular reactant can diffuse into the TOT host crystal lattice and reacts with the included molecule (guest) in characteristic ways, differing from those occurring in liquid solutions. Several aspects of the action of hydrogen halides (HCl, HBr) on the chemical behavior of included oxiranes were investigated for solid-gas and solid-liquid (aqueous) systems. Under well established experimental conditions, these reactions gave regiospecifically one target product and were asymmetric. The included substrate underwent first an acid-catalyzed allylic isomerization that is cage-specific and mostly quantitative. In sheer contrast, strong basic conditions were required to promote, in reduced yield, the analogous transformation in solution. The regiospecificity and enantioselectivity of several intra-crystalline conversions allowed the accurate determination of the absolute configuration of several guest molecules. Kinetic measurements were achieved that disclosed some striking features of this new type of heterogeneous reactions. Tentative models for the cage stereoselective mechanisms are briefly discussed.
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  • 91
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The complex formation by Co2+, Ni2+, Cu2+, Zn2+, and Cd2+ with tris[2-(dimethylamino)ethyl]amine (N(CH2CH2NMe2)3, Me6tren) was investigated at 25° and at an ionic strength of 1, using VIS spectroscopy and potentiometric measurements. The stability constants of these complexes are compared with those of tris(2-aminoethyl)amine (N(CH2CH2NH2)3, tren), obtained under the same conditions. The values of the constants for Me6tren are much lower than those for tren, due to the bulky Me substituents. The values of the constants can be correlated with the ability of the individual metal ions to adopt coordination number 5. This appears to be easier for Cu2+ and Co2+ than for Cd2+ and Zn2+ and is very difficult for Ni2+. The 1:1 complexes [ML(H2O)]2+ are monoprotonic acids whose pKs values are similar or lower than those of the corresponding aquametal ions. The X-ray crystal structure of the copper(II) complex [Cu(SO4)(Me6tren)] · 8H2O reveals pentacoordination at the central ion. The UV/VIS spectra of the aqueous solutions of the Co2+, Ni2+, and Cu2+ 1:1 complexes confirm that the same coordination number is present also in these complexes.
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  • 92
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    Helvetica Chimica Acta 77 (1994), S. 1768-1772 
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The structure of peregrine (1), a norditerpenoid alkaloid isolated from Delphinium peregrinum var. elongatum BOISS., was revised on the basis of the 1H-COSY, HMQC, HMBC, and ROESY NMR spectra and of the X-ray analysis of its parent alcohol 2. Some of the 13C-NMR resonances of 1 and the related alkaloids peregrine alcohol (2), 14-O-acetylperegrine (3), bicoloridine (4), bicoloridine alcohol (5), 6-O-acetylbicolorine (6), bicolorine (7), and 14-O-acetylbicolorine (8), were also reassigned.
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  • 93
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The antivirally active 3′-deoxyadenylyl-(2′-5′)-3′-deoxyadenylyl-(2′-5′)-3′-deoxyadenosine (cordycepin trimer core) was modified at the 2′- or 5′-terminus, by attachment of cholesterol via a carbonate bond (→ 15) or a succinate linker (→ 16 and 27) to improve cell permeability. The corresponding monomeric conjugates 4, 7, and 21 of cordycepin were prepared as model substances to study the applicability of the anticipated protecting groups - the monomethoxytrityl (MeOTr), the (tert-butyl)dimethylsilyl (tbds), and the β -eliminating 2-(4-nitrophenyl)ethyl (npe) and 2-(4-nitrophenyl)ethoxycarbonyl (npeoc) groups - for the final deblocking steps without harming the ester bonds of the conjugate trimers. The syntheses were performed in solution using phosphoramidite chemistry. The fully protected trimer conjugates 13, 14, and 26 as well as all intermediates were characterized by elemental analyses, UV and 1H-NMR spectra. The deblocked conjugates 15, 16, and 27 were pure according to HPLC and showed the correct compositions by mass spectra. Comparative biological studies indicated that cordycepincholesterol conjugate trimers 16 and 27 were 333- and 1000-fold, respectively, more potent inhibitors of HIV-1-induced syncytia formation than cordycepin trimer core.
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  • 94
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The pyrophosphoric-acid-analogue phosphonoformic acid (pfa) and the amino-acid-analogue (aminomethyl)phosphonic acid (ampa) both form, in the deprotonated state, i.e., as -OOC-PO32- and H2N—CH2—PO32-, respectively, five-membered chelate rings with metal ions. pfa inhibits both phosphate transport and virus replication, while ampa is a metabolic product of the common herbicide glyphosate ( = N-(phosphonomethyl)glycine). The acidity constants of H2pfa- and H2ampa± as well as the stability constants of the [M(Hpfa)], [M(pfa)]-, [M(Hampa)]+, and [M(ampa)] complexes, where M2+ = Mg2+, Ca2+, Sr2+, Ba2+, Mn2+, Co2+, Ni2+, Cu2+, Cu(2,2′-bipyridyl)2+, Cu(1,10-phenanthroline)2+, Zn2+, or Cd2+, have been determined by potentiometric pH titrations in aqueous solution at 25° and I = 0.1M (NaNO3). The structures of isomeric complexes and the connected intramolecular equilibria are deduced and evaluated based on the equilibrium constants measured and those calculated via the pKa values of the above mentioned ligands and previously established log K vs. pKa straight-line plots (H. Sigel et al., Helv. Chim. Acta 1992, 75, 2634) for a simple phosphonate-M2+ coordination. pfa forms stronger complexes than ampa with all the above mentioned metal ions, with the single exception of [Cu(ampa)] which is slightly more stable than [Cu(pfa)]-. In neutral solutions, more precisely at pH of ca. 6, pfa complexes of alkaline-earth-metal ions retain one phosphonate-bound proton, [M(Hpfa)], while those of the transition-metal ions chelate with the trianionic ligand, pfa3-. In accord with increasing ligand-basicity, the stability-constant order for all metal-ion complexes is oxalate 〉 pfa 〉 pyrophosphate but, owing to proton competition in pyrophosphate, in neutral solutions metal-ion complexation of pfa3- competes with P2O74-. With ampa alkaline-earth-metal ions interact only with the phosphonate group of even the dianionic ligand (though Mg2+ appears to form a low fraction of a [Mg(ampa)] chelate) while transition-metal ions form chelates which are comparable in stability to those of glycinate.
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  • 95
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    Helvetica Chimica Acta 77 (1994), S. 1773-1780 
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The crystal structure of the Sb2F11 salt of the 2-phenyladamant-2-yl cation, 1 · Sb2F11, was determined at 183 K (P21/c, R1 = 0.0652, σ(C—C) = 0.02 Å), because earlier published results indicated a charge delocalization from the cationic C(2) into the σ framework (C—C hyperconjugation) and a bending of the C(2) bridge. In the structure of 1, a displacement of the C(2) bridge by 7.8(12)° from the symmetrical position and C—C bond-length deviations from expectation values were found which are in agreement with preferential C—C hyperconjugation on one face of C(2). The interactions of 1 with two Sb2F11 counterions nearest to C(2) also indicate different behaviour of the two faces of C(2). The benzylic resonance in 1 is confirmed.
    Additional Material: 5 Ill.
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  • 96
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The bicyclic monoselenoacetal 7, easily obtained from (±)-7-oxabicyclo[2.2.1]hept-5-en-2-one (6) via a radical addition-acyl migration sequence, was converted to racemic 12-epiprostaglandins 3 and 4. The key intermediate was the all-cis-formyllactone 2b related to Corey lactone (see 12; Scheme 1). The presence of a (tert-butyl)-dimethylsilyl protective group for the 11-OH substituent (prostaglandin numbering) was found to be crucial in avoidingβ -elimination and epimerization during the Wittig-Horner reaction (Scheme 2). Epimerization at C(12) at the formyllactone stage (see 2b) was also possible and gave the known precursor 1b of naturally occurring prostaglandins and analogs.
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  • 97
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: While trialkylamines and dialkyl(phenyl)amines do not react with CS2 in the sense of an addition reaction, the analogous phosphines react smoothly. Attempts to interpret the reaction course on the basis of semiempirical, HF, MP2, and MP4 calculations of energy changes failed completely. To understand why Me3P or Me2PhP react so vigorously (liquid phase, 300 K) with CS2, CASSCF and MRSDCI calculations must be carried out.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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  • 98
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 0The bipyridyl-armed tetra-p-(tert-butyl)calix[4]arenes 1-5 were synthesized from tetra-p-(tert-butyl)-calix[4]arene A and 6-(bromomethyl)-6′-methyl-2,2′-bipyridine (B) by direct base-strength-driven regioselective O-alkylation or by stepwise procedures. Preliminary complexation studies of the ligands 1-3 with CuI affording the complexes 6-8 are described.
    Type of Medium: Electronic Resource
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  • 99
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: (Hydroxymethyl)bilane synthase (HMBS) catalyses the conversion of porphobilinogen (2) into the (hydroxymethyl)bilane derivative 3, a linear tetrapyrrolic intermediate in the biosynthesis of haem, chlorophyll, and related pigments. The conversion involves the sequential formation of four intermediate covalent enzyme-substrate complexes, before the product is released. We analysed the pre-steady-state kinetics of the formation of the complexes, taking advantage of their remarkable chemical stability allowing chromatographic separation. The experimental approach involved the generation of the complexes while HMBS was immobilised on an anion-exchange column. A solution being 0.2 Km in substrate was pumped through the column during a time interval which was varied to sample the pre-steady-state period. Then, the enzyme and enzyme-substrate complexes were eluted and their proportions evaluated. A computer simulation of the pre-steady-state time course, in combination with a χ2 fitting to the experimental data, allowed the specificity constants kcat/Km for the individual steps of the process to be derived. By repeating the analysis with variants of HMBS in which specific amino acids were replaced by others, we demonstrated that it is possible to trace the consequences of amino-acid replacements down to the individual steps of the reaction sequence. Since the positions of the amino acids concerned in the three-dimensional structure were known, detailed structure-function relationships become evident in this way.
    Additional Material: 2 Ill.
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  • 100
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Cyclic oligomers of (R)-3-hydroxyvaleric acid (3-HV) are prepared from the monomer by three different methods, giving various ratios of the oligomers. The macrocycles containing three to twelve 3-HV units (12- to 48-membered rings) are isolated in pure form by chromatography. The triolide 3 can be separated by distillation and isolated on large scale. Biopol, the copolymer of (R)-3-hydroxybutanoic acid (3-HB) and (R)-3-hydroxyvaleric acid (3-HV), is degraded to mixtures of Me- and Et-substituted triolides (‘mixolides’) with high crystallization tendency. The X-ray crystal structures of the tetrolide 4, pentolide 5, hexolide 6, heptolide 7, and of two ‘mixolides’ (with inclusions of solvent) have been determined (Figs. 3-7, 10, and 11) and are compared with those of the corresponding 3-HB derivatives reported previously. From the structural data, a 31 and a 21 helix of 3-HV can be modelled, and the latter one compared with helix structures of P9(3-HB) and P(3-HV) derived from stretch-fibre X-ray scattering. Crystals of a water-containing NaSCN complex of the triethyl triolide 3 were obtained in good quality for X-ray analysis. The structure (Figs. 12, 13, and Table 6) contains an interesting array of C=O and H2O O-atoms around the Na+ ions along a channel-type tube (a-axis of the crystal) which may be relevant to the role of P(3-HB) and P(3-HV) as components of cellular ion channels.
    Additional Material: 13 Ill.
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