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  • 1
    Electronic Resource
    Electronic Resource
    Multiple forms of phosphoenolpyruvate carboxylase in mesophyll, epidermal and guard cells of Vicia faba (1992)
    Copenhagen : Munksgaard International Publishers
    Physiologia plantarum 86 (1992), S. 0 
    Details
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The distribution of phosphoenolpyruvate carboxylase (PEPCase, EC 4.1.1.31) in different leaf-cell-types and tissues of Vicia faba L. cv. 3-fach Weiße was studied. The highest specific PEPCase activity was found in guard cell protoplasts (16.3 µmol mg−1 protein h−1) whereas for epidermal and mesophyll protoplasts remarkably lower specific activities were found (1.6 and 1.0 µmol mg−1 protein h−1, respectively). On chlorophyll and protoplast basis, a similar distribution of enzyme activity was observed. Compared with epidermal extracts, the specific PEPCase activity of mesophyll tissue was 17-fold lower. Immunological studies with polyclonal antibodies to PEPCase indicated 3 immunoreactive proteins in epidermal tissue and guard cell protoplasts with molecular masses of 107 000, 110 000, and 112 000. Only the Mr 107 000 protein was found in extracts of mesophyll and epidermis protoplasts. Western immunoblots after native electrophoresis of epidermal and mesophyll proteins showed a significant difference in PEPCase mobility. It is assumed, that the immunostained proteins of Mr 110 000 and 112 000 represent isoforms or subunits of the PEPCase and that they are involved in stomatal movements.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1034/j.1399-3054.1992.860219.x
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  • 2
    Electronic Resource
    Electronic Resource
    Partial purification and characterization of stomatal phosphoenolpyruvate carboxylase from Vicia faba (1993)
    Oxford, UK : Blackwell Publishing Ltd
    Physiologia plantarum 87 (1993), S. 0 
    Details
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Stomatal phosphoenolpyruvate carboxylase (PEPCase EC 4.1.1.31), extracted from abaxial epidermal peels of Vicia faba L. cv. Frühe Weiβkeimige, was partially purified by ammoniumsulfate precipitation, and molecular sieve (Sepharosc S-400) and ion exchange (DEAE-Sepharose) chromatography. The partially purified enzyme, essentially free of a PEPCase isoform existing in mesophyll and epidermal cells, had a specific activity of 300 nkat mg-1 protein at 25°C. Western immunoblot analysis revealed that the stomatal enzyme had two bands (M: of 110000 and 112000), crossreacting with PEPCase antibodies raised against PEPCase from Ka-lanchoe daigremontiana. The native molecular mass of the enzyme (467000) points to a tetrameric subunit structure. The temperature optimum was found to be 35°C; cold treatments of PEPCase before assaying were accompanied by inactivation. The energy of activation was calculated to 51 kJ mol-1. The kinetic behaviour of the enzyme at fixed MgCl2 concentrations is characterized by a pH optimum between pH 8.0–8.2 with or without 1 mM malate or 5 mM glucose-6-phosphate (Glc-6-P), but a combination of both effectors resulted in a shift of the optimum to pH 7.6. The enzyme showed a pH sensitive inhibition by 1 mM malate and an activation by Glc-6-P. At low pH (6–7), Glc-6-P was able to compensate for the malate induced inhibition of the enzyme. Malate and Glc-6-P both affected Km(PEP), drastically and influenced Vmax at pH 7, but not at pH 8.3. The inhibition constant of malate was determined to be 1.2 mM at pH 7. From the Dixon plot, a competitive inhibition of malate was assumed under defined assay conditions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1399-3054.1993.tb08796.x
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  • 3
    Electronic Resource
    Electronic Resource
    Oxidation von Tetradekan durch Pseudomonadaceae (1971)
    Springer
    Naturwissenschaften 58 (1971), S. 55-55 
    Details
    ISSN: 1432-1904
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Natural Sciences in General
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00620811
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  • 4
    Electronic Resource
    Electronic Resource
    Differential effects of electrofusion and electropermeabilization parameters on the membrane integrity of plant protoplasts (1990)
    Springer
    Planta 180 (1990), S. 598-602 
    Details
    ISSN: 1432-2048
    Keywords: Electrofusion ; Electropermeabilization ; Ethane ; Lipid peroxidation ; Membrane integrity ; Protoplast (membrane integrity) ; Vicia
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Ethane was used as an indicator of lipid peroxidation in order to characterize the membrane damage induced by electrical pulses during the processes of electrofusion and electropermeabilization. The increase of ethane in fused protoplasts ofVicia faba L. was found to be correlated with the intensity of field strength and pulse number, which also affected the yield of hybrids. The degree of membrane damage is postulated to depend on the accumulation of lipid free-radicals, which can be increased by light, by longer storage time of protoplasts and by higher field strength and pulse number. As a result, the conditions for electropermeabilization lead to greater membrane damage compared with those for electrofusion. The measurement of ethane production may prove to be useful for characterization of the membrane integrity, viability and regeneration ability of protoplasts.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02411459
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  • 5
    Electronic Resource
    Electronic Resource
    A regeneration protocol for sunflower (Helianthus annuus L.) protoplasts (1996)
    Springer
    Plant cell reports 15 (1996), S. 742-745 
    Details
    ISSN: 1432-203X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Hypocotyl protoplasts of four different Helianthus annuus genotypes were cultivated for 22–28 days in agarose droplets covered with liquid medium. In the first week, supplementation of the medium with plant growth regulators was at a 0.8/1 ratio of cytokinin and auxin followed by a high auxin concentration in the second week and a cytokinin to auxin ratio of 8/1 in the third and fourth week. Following transfer onto solid medium containing cytokinin and auxin in a proportion of 40/1 morphogenic callus started to form globular structures that developed into leaf primordia. Subsequent shoot elongation and rooting were obtained on hormone free medium after dipping the cut shoots into high auxin solution. Thirteen weeks after protoplast isolation, plantlets could be transferred to the greenhouse. Shoot regeneration was obtained for all four cultivars (Florom-328, Cerflor, Euroflor, Frankasol) at different rates reflecting their regenerative potential.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00232219
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  • 6
    Electronic Resource
    Electronic Resource
    A regeneration protocol for sunflower (Helianthus annuus L.) protoplasts (1996)
    Springer
    Plant cell reports 15 (1996), S. 742-745 
    Details
    ISSN: 1432-203X
    Keywords: Abbreviations: BAP, 6-benzylaminopurine; 2,4-D, 2,4-dichlorophenoxyacetic acid; FeNaEDTA, ethylenediamine-tetraacetic acid ferric sodium salt; IAA, indole acetic acid; MES, morpholinoethane sulfonic acid; NAA, 1-naphtalene acetic acid
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary. Hypocotyl protoplasts of four different Helianthus annuus genotypes were cultivated for 22–28 days in agarose droplets covered with liquid medium. In the first week, supplementation of the medium with plant growth regulators was at a 0.8/1 ratio of cytokinin and auxin followed by a high auxin concentration in the second week and a cytokinin to auxin ratio of 8/1 in the third and fourth week. Following transfer onto solid medium containing cytokinin and auxin in a proportion of 40/1 morphogenic callus started to form globular structures that developed into leaf primordia. Subsequent shoot elongation and rooting were obtained on hormone free medium after dipping the cut shoots into high auxin solution. Thirteen weeks after protoplast isolation, plantlets could be transferred to the greenhouse. Shoot regeneration was obtained for all four cultivars (Florom-328, Cerflor, Euroflor, Frankasol) at different rates reflecting their regenerative potential.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002990050111
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  • 7
    Electronic Resource
    Electronic Resource
    Dark fixation of CO2 by flowers of cut roses (1976)
    Springer
    Planta 131 (1976), S. 51-55 
    Details
    ISSN: 1432-2048
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Complete flower heads of cut roses (cv. Baccara) were exposed to 14CO2 for 1–4 h. The flower tissue was able to fix CO2 via PEP carboxylase (E.C. 4.1.1.31) in the dark; various TCA products were identified in petals, ovary and anthers, including malate, aspartate, citrate, serine/glycine, glutamate and asparagine. The concentrations of these labelled products were similar in the petals and anthers, but lower in the ovary. After removal of the petals the amounts of these components were reduced in the anthers to a relatively high extent (to 1/6), whereas the amounts in the ovary increased slightly. It is suggested that the petals are necessary for supplying the anthers with the described components.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00387345
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  • 8
    Electronic Resource
    Electronic Resource
    Modulation of the activity of phosphoenolypyruvate carboxylase during potassium-induced swelling of guard-cell protoplasts of Vicia faba L. after light and dark treatments (1990)
    Springer
    Planta 180 (1990), S. 188-193 
    Details
    ISSN: 1432-2048
    Keywords: Guard cell protoplast ; Malate Phospho ; enolpyruvate caboxylase (guard cell) ; Vicia (guard cell protoplast)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Phosphoenolpyruvate carboxylase (PEPCase; EC 4.1.1.31) activity was found to be modulated by light and darkness when measured in the presence of K+, which had been added to induce swelling of guard-cell protoplasts (GCPs) from Vicia faba L., whereas no modulation was detected in the absence of K+ (PEPcase activity remained constant at 1.5±0.15 pmol PEP metabolized · GCP−1 ·h−1; subsequently, pmol GCP−1 ·h−1 will be used). The activity of PEPCase increased by 100% (from 1.5 to 3 pmol·protoplast−1·h−1) in darkness and by 200% (from 1.7 to 5 pmol·protoplast−1· h−1) in light and oscillations in activity of these magnitudes were repeated at intervals of 2 min (dark) and 2.5 min (light) for a period of 10 min during K+-induced increase in the volume of GCPs. The oscillations were reflected in changes in malate-pool sizes determined in plastids, mitochondria and the supernatant fraction (consisting of the cytosol and the vacuole). Malate probably functioned as a mitochondrial substrate, thus supplying ATP for K+ uptake and the swelling of the protoplasts. On the basis of the present paper and previous results (H. Schnabl and B. Michalke 1988, Life Sci. Adv. Plant Physiol. 7, 203–207) involving adenine nucleotidepool sizes in fractionated GCPs, a model is proposed to explain the cause-effect relationship between K+, PEPCase, the cytosolic and mitochondrial malate levels and ATP levels during the K+-induced increase of GCP volume.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00193994
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  • 9
    Electronic Resource
    Electronic Resource
    Production of hybrid cells from single protoplasts of sunflower hypocotyl and broad bean guard cells by electrical fusion (1998)
    Springer
    Plant cell, tissue and organ culture 55 (1998), S. 59-62 
    Details
    ISSN: 1573-5044
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The C4-directed enzymatic apparatus in guard cells is known to be coupled with a reduction in photorespiration resulting in a higher survival rate and yield potential of crops. This has led to searches for guard-cell-specific genes and promoters and methods for transferring them into C3-plants. To explore this possibility we performed somatic fusions between guard cell protoplasts from Vicia faba and hypocotyl protoplasts from Helianthus annuus, using a technique which allows fusion of a single pair of individually selected protoplasts. We obtained fusions in 30–70% of attempts. Culture of the hybrid fusion products in a liquid nutrient medium, without conditioning or feeder cells, produced microcolonies consisting of 8–9 cells within 9 days of culture.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1026480331508
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  • 10
    Electronic Resource
    Electronic Resource
    Ultrastructure of sunflower protoplast derived ealluses differing in their regenerative potential (1994)
    Springer
    Plant cell, tissue and organ culture 37 (1994), S. 277-285 
    Details
    ISSN: 1573-5044
    Keywords: embryoid-like structures ; Helianthus annuus L. ; mesophyll protoplasts ; microcalluses ; ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The ultrastructural properties of microcalluses derived from mesophyll protoplasts of commercial sunflower (Helianthus annuus L.) cultivars were investigated by light and electron microscopy. Two culture regimes were chosen: Regime A giving rise to callus formation but of little embryogenic potential and regime B resulting in higher embryogenicity. Bipolar colonies that developed during early stages of regime A were found to be composed of mostly degenerated structures. No differentiation or embryonal organization as suggested by the compactness and shape of the microcalluses could be observed. Amorphous calluses obtained at later stages of the same regime consisted of small groups of meristematic as well as vacuolated cells. Incomplete cellular divisions occurred in almost all colonies grown under the regime A, causing most probably the lack of further callus organization. In contrast calluses of irregular shape, cultivated under regime B, mostly lacked incomplete cell partitioning but showed the formation of organized regions. These structural investigations can give us a tool to identify and characterize the quality of embryogenic calluses.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00042341
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