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  • 1
    Electronic Resource
    Electronic Resource
    Changes in phenylpropanoid metabolites associated with homology-dependent silencing of phenylalanine ammonia-lyase and its somatic reversion in tobacco (2001)
    Copenhagen : Munksgaard International Publishers
    Physiologia plantarum 111 (2001), S. 0 
    Details
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Gene silencing of phenylalanine ammonia-lyase (PAL) in transgenic tobacco (Nicotiana tabacum L.) is manifested phenotypically by reduced growth, altered leaf morphology, and reduced levels of phenylpropanoid compounds. Here we report the rare event of somatic reversion from silencing to PAL over-expression in tobacco harboring the bean PAL2 gene. This phenomenon allows the comparison of the effects of PAL under- and over-expression in the same plant. A comparison of gene silenced and revertant tissues reveals striking differences in lignin content and monomer composition, and both qualitative and quantitative differences in soluble and cell wall bound phenylpropanoid compounds in the recovered sector.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1034/j.1399-3054.2001.1110202.x
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  • 2
    Electronic Resource
    Electronic Resource
    Near-term impacts of elevated CO2, nitrogen and fungal endophyte-infection on Lolium perenne L. growth, chemical composition and alkaloid production (2005)
    Oxford, UK : Blackwell Science Ltd
    Plant, cell & environment 28 (2005), S. 0 
    Details
    ISSN: 1365-3040
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Carbon dioxide has been rapidly accumulating in the atmosphere and is expected to continue to do so. This accumulation is presumed to have important direct effects on plant growth. The interacting affects of a small increase in CO2 concentration (466 p.p.m., approximately 30% increase from current ambient conditions), nitrogen fertilization and fungal endophyte (Neotyphodium lolii) infection on the growth and chemical composition of perennial ryegrass (Lolium perenne) were investigated. It was found that dry mass production was approximately 50% greater under elevated CO2 than under ambient CO2, but only in conditions of high soil N. High molecular weight carbohydrates and total carbohydrates (LMW + HMW CHO) depended on an interaction between CO2 and endophyte infection. Infected plants contained significantly more carbohydrate than endophyte-free plants, and the difference was greatest in ambient CO2 conditions. Protein concentrations were also influenced by the interaction between CO2 and endophyte-infection. Endophyte-free plants had 40% lower concentrations of soluble protein under elevated CO2 than under ambient CO2, but this CO2 effect on soluble protein was largely absent in endophyte-infected plants. CO2, endophyte-infection and nitrogen interacted to influence the total chlorophyll concentration of the grass such that chlorophyll concentration was always lower in elevated CO2 but this decline was much greater in endophyte-free plants, particularly in conditions of high soil N. In the endophyte-infected plants, the concentrations of the pyrrolopyrazine alkaloid peramine depended on the interaction between CO2 and N fertilization such that peramine concentrations declined with increasing N at ambient CO2 but remained roughly constant across N levels at elevated CO2. A similar pattern was seen for the ergot alkaloid ergovaline. The biochemical responses of perennial ryegrass to elevated CO2 are clearly modified by the presence of endophytic fungi.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-3040.2005.01367.x
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  • 3
    Electronic Resource
    Electronic Resource
    Regulation of phenylpropanoid metabolism by exogenous precursors in axenic cultures of Sphagnum fallax (1995)
    Oxford, UK : Blackwell Publishing Ltd
    Physiologia plantarum 95 (1995), S. 0 
    Details
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Sphagnum plantlets, cultivated in continuous-feed bioreactors, are characterised by high levels of free endogenous phenolics and a pronounced excretion of some phenolics into the effluent culture medium. The transfer of Sphagnum fallax, precultivated in continuous-feed bioreactors, to batch cultures resulted in an increased flux through phenylpropanoid metabolism and an accumulation of p-coumaric acid to 0.1 μM and of trans-sphagnum acid up to 0.5 μM in the external medium [3H]-labelled L-phenylalanine (7.7 GBq mol−1) was rapidly taken up, resulting in an enhanced synthesis and excretion of p-coumaric and trans-sphagnum acid. Specific activities were 6.9 and 5.4 GBq mol−1, respectively, for these cinnamic acids excreted into the external medium. Endogenous pools of trans-cinnamic and p-coumaric acid did not increase and no labelling could be detected in these compounds. Cell wall-bound activity amounted to ca 14% of the applied activity after 48 h of incubation, 59% of which was recovered in dioxane/2 M HCl extracts of the cell wall. Exogenously applied trans-cinnamic acid (0.1 mM) was taken up to 46% and resulted in a transient endogenous accumulation of trans-cinnamic acid, the level of free endogenous p-coumaric and trans-sphagnum acid was found to have decreased. The concentrations of p-coumaric and trans-sphagnum acid in the culture medium rose to 17 and 2.4 μM, respectively, after 48 h of incubation in 0.1 mMtrans-cinnamic acid. Exogenously applied p-coumaric acid (0.1 mM) was taken up to 79% from the incubation solution but not stored endogenously, as metabolic products trans-sphagnum acid and an unknown p-coumaric acid-conjugate accumulated in the external medium and endogenously. These results give evidence for the biosynthetical route from phenylalanine to sphagnum acid and a channelling of pathway intermediates by the enzymes L-phenylalanine ammonia-lyase (EC 4.3.1.5) and cinnamic acid 4-hydroxylase (EC 1.14.13.11).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1399-3054.1995.tb00812.x
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  • 4
    Electronic Resource
    Electronic Resource
    Mapping of caspase-2 in the rat and its exclusion as a candidate gene for lymphopenia (1999)
    Springer
    Mammalian genome 10 (1999), S. 244-248 
    Details
    ISSN: 1432-1777
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract. Caspase-2 is a member of the caspase family of cystein proteases involved in programmed cell death or apoptosis. Functional and genetic data suggest it as a candidate gene for lymphopenia (Lyp)—a susceptibility gene for rat diabetes—which is responsible for the T-cell lymphopenia in the diabetes–prone BB rat. Firstly, there is a higher frequency of apoptosis among recent thymic emigrants in the diabetes-prone BB rat than in the non-lymphopenic diabetes-resistant BB rat. Secondly, caspase-2 maps close to Tcrb on mouse Chromosome (Chr) 6, while Lyp is closely linked to Tcrb on the homologous rat Chr 4. In this paper, we report genetic fine-positioning and radiation hybrid mapping of caspase-2 in the rat. Both methods positioned caspase-2 to rat Chr 4 between markers Prss1 and D4Mit5. Since Lyp maps distally to D4Mit5, between markers D4Rat75 and Npy, we exclude caspase-2 as a candidate gene for Lyp.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003359900981
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    Paper (German National Licenses)
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