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  • 1
    Digitale Medien
    Digitale Medien
    Effects of glandular trichomes on the development of Phytophthora infestans infection in potato (S. tuberosum) (2000)
    Springer
    Euphytica 114 (2000), S. 165-174 
    Details
    ISSN: 1573-5060
    Schlagwort(e): bioassay ; exudates ; inoculation ; late blight ; resistance ; S. berthaultii
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract S. berthaulltii Hawkes, a wild potato species, possesses two types of glandular trichomes on its leaf surface: types A and B wich confer resistance to insects. Preliminary results indicated that the presence of glandular trichomes also confers resistance to Phytophthora infestans, the causal agent of late blight. In this paper we report the evaluation of trichome characteristics (density and exudate activities) performed on 8 lines of potato, including the control varieties Desirée and Tropicana, 5 hybrid lines derived from intercrosses and backcrosses between S. tuberosum and S. berthaultii and one accession of S. berthaultii. Whole plants of the 8 genotypes were inoculated with a spore suspension of Phytophthora infestans in order to evaluate their resistance to late blight. The resultant disease incidence correlated negatively with type A trichome density and with polyphenol-oxidase (PPO) activity of type A trichome glands. The removal of type B trichomes exudate by leaf dipping in ethanol did not influence the disease development after artificial inoculation of detached leaves. Type B trichome exudate was extracted and the fraction corresponding to Fatty Acids Sucrose Esters (FASE) was recovered after Thin Layer Chromatography and tested on the fungal mycelium in vitro. The FASE exhibited a slight inhibitory effect on mycelium growth. The results of the experiments are discussed, and several hypotheses regarding the possible role of types A and B trichomes are formulated.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1003924318577
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  • 2
    Digitale Medien
    Digitale Medien
    Preparation and homogeneity study of a mussel candidate reference material for certification of organotin compounds (1995)
    Springer
    Microchimica acta 120 (1995), S. 281-287 
    Details
    ISSN: 1436-5073
    Schlagwort(e): certified reference material ; mussel ; organotin ; homogeneity
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract Organotin compounds are currently determined in various environmental matrices (in particular water, sediment and shellfish) to form the basis of control measures for the levels of contamination, as required in some EC Directives. Accurate measurements are a prerequisite for the enforcement of this legislation, which implies that good quality control of determinations should be ensured. One of the tools for achieving accuracy is to use certified reference materials (CRMs). With regard to tin species, however, CRMs are rather scarce and mainly concern sediment and fish matrices certified for their butyltin content. The present study deals with the preparation of a mussel candidate reference material and the verification of its homogeneity prior to the certification of the contents of butyl- and phenyl-tin compounds. 100kg of mussels (Mytilus edulis) were collected, carefully washed with fresh water in order to eliminate matrix salts and immediately frozen by immersion in liquid nitrogen. The mussels were shelled (in the frozen state) and the edible part was stored in thermally sealed polyethylene bags which were stored at −25 °C. The frozen material was ground in a Teflon-coated grinding mill, spread on sterilized flat trays and freeze-dried. The freeze-dried material was then ground for 15 days in a zirconia ball mill and sieved on a titanium sieve to separate the fibrous part. Successively, the material was mixed for 15 days under argon atmosphere in a special polyethylene-lined mixing drum and bottled in brown Pyrex-glass bottles. 21 bottles were selected during the course of the bottling procedure to verify the within- and between-bottle homogeneity of the overall batch. The within-bottle homogeneity was verified by determining the organotin (butyl- and phenyltins) content for subsamples of 500 mg in ten replicates from one bottle, whereas the between-bottle homogeneity was controlled by one organotin measurement from each of 20 bottles. The analyses were performed by GC-MS. The results showed that the homogeneity of the material makes it suitable as a candidate reference material.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01244438
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  • 3
    Digitale Medien
    Digitale Medien
    Working Methods Paper: Critical considerations with respect to the identification of tin species in the environment (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 8 (1994), S. 541-549 
    Details
    ISSN: 0268-2605
    Schlagwort(e): Organotin ; identification ; mixed methylbutyl forms ; monophenyltin ; crosscomparison ; mis-interpretation ; Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Biogeochemical pathways of tin species in the environment are still controversial, e.g. with regard to methylation and transmethylation phenomena, owing to the fact that the identification of methylated tin-compounds is often difficult. The previous tentative identification of a mixed methylbutyltin compound in sediment and biological samples by GC/AAS after hydride generation gave an illustration of this problem. This compound was previously identified in sediments by other authors and also suspected to occur in a contaminated sediment sample from the Boyardville Marina, France. The retention time obtained by GC/AAS corresponded to the actual retention time of a mixed methylbutyltin calibrant. However, additional checks demonstrated that the compound detected was actually monophenyltin. This evidence was produced by a thorough analysis of a selected sediment sample by alternative techniques such as GC/AAS and GC/AES after pentylation, GC/FPD and GC/MS. The results presented highlight the need for a full identification of compounds to avoid mis-interpretation.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/aoc.590080607
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  • 4
    Digitale Medien
    Digitale Medien
    Determination of methylmercury in human hair by capillary GC with electron capture detection (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 8 (1994), S. 563-570 
    Details
    ISSN: 0268-2605
    Schlagwort(e): Methylmercury ; human hair ; capillary GC-electron capture detection ; Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: An analytical procedure was developed for the determination of methylmercury in human hair using capillary gas chromatography with electron capture detection (GC-ECD). Hair samples are digested in alkaline solution/toluene in an ultrasonic bath at about 50°C. After cooling and treatment with hydrochloric acid (6 mol I-1) and a saturated solution of copper sulphate, the organic phase is extracted with a cysteine solution. Methylmercury is back-extracted in toluene by adding copper sulphate and potassium bromide and analysed by GC-ECD using a DB17 capillary column. The practical detection limit of the method for methylmercury is 50 ng g-1 using 100 mg of hair sample. Column performances and injection reproducibility have been evaluated. Results on 13 samples of human hair are presented and related to the total mercury concentration. The method, consisting of the optimization of similar analytical procedures through improvements in the various steps, allows for sensitive and reliable quantitation of methylmercury in hair with good precision and accuracy.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/aoc.590080704
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