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  • 1
    Electronic Resource
    Electronic Resource
    Increased cytokinin levels in transgenic PSAG12–IPT tobacco plants have large direct and indirect effects on leaf senescence, photosynthesis and N partitioning (2000)
    Oxford, UK : Blackwell Science Ltd
    Plant, cell & environment 23 (2000), S. 0 
    Details
    ISSN: 1365-3040
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: We studied the impact of delayed leaf senescence on the functioning of plants growing under conditions of nitrogen remobilization. Interactions between cytokinin metabolism, Rubisco and protein levels, photosynthesis and plant nitrogen partitioning were studied in transgenic tobacco (Nicotiana tabacum L.) plants showing delayed leaf senescence through a novel type of enhanced cytokinin syn-thesis, i.e. targeted to senescing leaves and negatively auto-regulated (PSAG12–IPT), thus preventing developmental abnormalities. Plants were grown with growth-limiting nitrogen supply. Compared to the wild-type, endogenous levels of free zeatin (Z)- and Z riboside (ZR)-type cytokinins were increased up to 15-fold (total ZR up to 100-fold) in senescing leaves, and twofold in younger leaves of PSAG12–IPT. In these plants, the senescence-associated declines in N, protein and Rubisco levels and photosynthesis rates were delayed. Senescing leaves accumulated more (15N-labelled) N than younger leaves, associated with reduced shoot N accumulation (–60%) and a partially inverted canopy N profile in PSAG12–IPT plants. While root N accumulation was not affected, N translocation to non-senescing leaves was progressively reduced. We discuss potential consequences of these modified sink–source relations, associated with delayed leaf senescence, for plant productivity and the efficiency of utilization of light and minerals.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-3040.2000.00544.x
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  • 2
    Electronic Resource
    Electronic Resource
    The Institute for Interlaboratory Studies (i.i.s.) now has formal accreditation for the organisation of proficiency tests (2000)
    Springer
    Accreditation and quality assurance 5 (2000), S. 215-215 
    Details
    ISSN: 1432-0517
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s007690050448
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  • 3
    Electronic Resource
    Electronic Resource
    Proficiency testing schemes for polytechnic students: an educational project in The Netherlands (2000)
    Springer
    Accreditation and quality assurance 5 (2000), S. B114 
    Details
    ISSN: 1432-0517
    Keywords: Key words Quality ; Proficiency testing scheme ; Education ; Polytechnics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract  In the August 1999 issue of Accreditation and Quality Assurance reference was made to proficiency testing schemes organised for students at polytechnics in The Netherlands. The present paper describes in more detail this educational project which aims at increasing students' awareness of quality assurance and quality control (QA/QC) at polytechnics. The project has to be seen in relation to other regular activities to educate and train students and to prepare them for working in an analytical laboratory. This combined effort should result in well-educated and well-trained students with the right attitude to analytical work and to QA/QC. The project was organised under the auspices of the Working Group "Quality Assurance in Laboratory Education" (KILO).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s007699900126
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  • 4
    Electronic Resource
    Electronic Resource
    Development of a plant regeneration system based on friable embryogenic callus in the ornamental Alstroemeria (2000)
    Springer
    Plant cell reports 19 (2000), S. 529-534 
    Details
    ISSN: 1432-203X
    Keywords: Key words Friable embryogenic callus ; Regeneration ; Rhizome ; Alstroemeria
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  Stem segments of seedlings from two Alstroemeria breeding lines, cultured on media supplemented with 4 mg/l 2,4-dichlorophenoxyacetic acid and 0.5–1.0 mg/l 6-benzylaminopurine (BA), initiated soft callus, which became compact after subculture on a medium with only 0.5 mg/l BA. Friable embryogenic calli were initiated from compact callus on a medium supplemented with 10 mg/l picloram. Proembryos developed from friable embryogenic calli via embryos into plants after subculture on medium supplemented with 0.1 mg/l BA. The proembryos formed friable embryogenic calli again after culture on medium supplemented with 10 mg/l picloram. The total time needed to regenerate a complete plantlet from friable callus was approximately 6 months. This system for the production of embryogenic material is considered to have valuable applications for genetic transformation in Alstroemeria.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002990050768
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  • 5
    Electronic Resource
    Electronic Resource
    Development of amylose-free (amf) monoploid potatoes as new basic material for mutation breeding in vitro (2000)
    Springer
    Potato research 43 (2000), S. 179-189 
    Details
    ISSN: 1871-4528
    Keywords: Solanum tuberosum L. ; prickle pollination ; ploidy level ; flow-cytometry ; adventitious shoots ; in vitro tuber induction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary For the induction and selection of double mutants with altered starch composition, a uniform (homohistont) amylose-free (amf) monoploid as basic plant is of vital importance. Therefore, newamf monoploids had to be developed via prickle pollination. And 26 monoploids were obtained which were screened in vitro for vigour, leaf size and for the percentage of monoploid cells. The number of monoploid cells was underestimated at about 28%. Seven vigorous monoploids were tested in vitro for tuberization capacity, which varied from 0 to 100%. After regeneration in vitro, 0 to 3.7 adventitious shoots per leaf explant were formed. The tuberization capacity of these shoots varied from 0 to 48. Twoamf monoploids were selected which were vigorous and tuberized well in vitro. They are the basis for the application of an in vitro mutation breeding protocol that should lead to the induction and selection of new starch mutants in potato.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02357958
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