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  • 1
    Electronic Resource
    Electronic Resource
    No Induction of β-oxidation in leaves of Arabidopsis that over-produce lauric acid (1999)
    Springer
    Planta 207 (1999), S. 385-392 
    Details
    ISSN: 1432-2048
    Keywords: Key words: Acyl-CoA oxidase ; Arabidopsis (β-oxidation) ; Beta-oxidation ; Gene expression ; Lauric acid ; Medium-chain thioesterase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract. Leaves from transgenic Brassica napus L. plants engineered to produce lauric acid show increased levels of enzyme activities of the pathways associated with fatty acid catabolism (V.A. Eccleston and J.B. Ohlrogge, 1998, Plant Cell 10: 613–621). In order to determine if the increases in enzyme activity are mirrored by increases in the expression of genes encoding enzymes of β-oxidation, which is the major pathway of fatty acid catabolism in plants, the medium-chain acyl-acyl carrier protein (ACP) thioesterase MCTE from California bay (Umbellularia californica) was over-expressed under the control of the cauliflower mosaic virus 35S promoter in Arabidopsisthaliana (L.) Heynh. Arabidopsis was the most suitable choice for these studies since gene expression could be analyzed in a large number of independent MCTE-expressing lines using already well-characterized β-oxidation genes. Levels of MCTE transcripts in leaves varied widely over the population of plants analyzed. Furthermore, active MCTE was produced as determined by enzymatic analysis of leaf extracts of MCTE-expressing plants. These plants incorporated laurate into triacylglycerol of seeds, but not into lipids of leaves as shown by gas-chromatographic analysis of total fatty acid extracts. The expression levels of the β-oxidation and other genes that are highly expressed during developmental stages involving rapid fatty acid degradation were measured. No significant difference in gene expression was observed among MCTE-expressing plants and transgenic and non-transgenic controls. To eliminate the possibility that post-translational mechanisms are responsible for the observed increases in enzyme activity acyl-CoA oxidase activity was also measured in leaves of MCTE-expressing plants using medium and long chain acyl-CoA substrates. No significant increases in either medium- or long-chain acyl-CoA oxidase activities were detected. We conclude that endogenous β-oxidation is sufficient to account for the complete degradation of laurate produced in rosette leaves of Arabidopsis expressing MCTE.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004250050496
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  • 2
    Electronic Resource
    Electronic Resource
    Developmental regulation of expression of the malate synthase gene in transgenic plants (1990)
    Springer
    Plant molecular biology 15 (1990), S. 539-549 
    Details
    ISSN: 1573-5028
    Keywords: Gluconeogenesis ; glyoxylate cycle ; malate synthase ; seed germination ; transgene expression
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The cucumber malate synthase (MS) gene, including 1856 bp of 5′ non-trnascribed sequence, has been transferred into Petunia (Mitchell) and Nicotiana plumbaginifolia plants using an Agrobacterium binary vector. The transferred gene is found in variable copy number in different transformants, and is stably transmitted in each case as a single Mendelian character. Transgene mRNA accumulates in the seedling during the first three days of germination, then declines in amount as the cotyledons emerge from the seed. The decline is more pronounced in light-grown seedlings than in dark-grown seedlings. Expression of the MS transgene is also detected at a low level in petals of transformed Petunia plants. In these respects the pattern of MS gene expression is similar in cucumber and in trnasformed plants, showing that the transferred DNA fragment contains a functional MS gene. A 1076 bp fragment of 5′ sequence was linked to the β-glucuronidase reporter gene and transferred into Nicotiana, where it was shown to direct temporal and spatial patterns of expression similar to that of the complete MS gene. However, histochemical localisation of β-glucuronidase activity demonstrated that the chimaeric gene is expressed not only in cotyledons of transgenic plants, but also in endosperm and some hypocotyl cells during early germination. The relevance of these findings to the control of malate synthase gene expression is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00017829
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  • 3
    Electronic Resource
    Electronic Resource
    Distinct cis-acting elements direct the germination and sugar responses of the cucumber malate synthase gene (1996)
    Springer
    Molecular genetics and genomics 250 (1996), S. 153-161 
    Details
    ISSN: 1617-4623
    Keywords: Cucumber (Cucumis sativus L.) ; Malate synthase ; Glyoxylate cycle ; Gene transcription ; Metabolic regulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The malate synthase gene (ms) promoter in cucumber (Cucumis sativus L.) was investigated with the aim of distinguishing DNA sequences mediating regulation of gene expression by sugar, and expression following seed germination. Promoter deletions were constructed and their ability to direct expression of theβ-glucuronidase (gus) reporter gene was investigated in transgenicNicotiana plumbaginifolia. Gene expression was assayed in germinating seeds and developing seedlings (the germination response) and in seedlings transferred from light into darkness with and without sucrose (the sugar response). As progressively more of the promoter was deleted from the 5′ end, first the sugar response and then the germination response was lost. Thus, distinct regions of the promoter are required for carbohydrate control and for regulation of gene expression in response to germination. Sequence comparisons of thems promoter with that of the isocitrate lyase gene (icl) of cucumber have previously identified four IMH (ICL-MS Homology) sequences. One such sequence, IMH2, is shown here to be implicated in the sugar response of thems gene. The 17 bp sequence, which when deleted from thems gene results in loss of the germination response, contains a 14 bp sequence which is similar to a sequence in theicl promoter, which we refer to as IMH5. Furthermore, this sequence has similarity withamdI9-like sequences in filamentous fungi, which conferfacB-mediated acetate inducibility on several genes, including those encoding ICL and MS.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02174174
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