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  • 1
    Electronic Resource
    Electronic Resource
    Formalism for the calculation of local elastic constants at grain boundaries by means of atomistic simulation (1990)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 67 (1990), S. 2370-2379 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A new formalism for use in atomistic simulations to calculate the full local elastic-constant tensor in terms of local stresses and strains is presented. Results of simulations on a high-angle (001) twist grain boundary are illustrated, using both a Lennard–Jones potential for Cu and an embedded-atom potential for Au. The two conceptionally rather different potentials show similar anomalies in all elastic constants, confined to within a few lattice planes of the grain boundary, with an especially dramatic reduction in the resistance to shear parallel to the grain-boundary plane. It is found that the primary cause of the anomalies is the atomic disorder near the grain boundary, as evidenced by the slice-by-slice radial distribution functions for the inhomogeneous interface system.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.345533
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  • 2
    Electronic Resource
    Electronic Resource
    Diurnal changes in the regulatory properties of PEP-carboxylase in Crassulacean Acid Metabolism (CAM) (1981)
    Oxford, UK : Blackwell Publishing Ltd
    Plant, cell & environment 4 (1981), S. 0 
    Details
    ISSN: 1365-3040
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Abstract. The CAM plants Kalanchoe tubiflora and K. blossfeldiana were grown under photoperiodically controlled conditions (short days). In these plants, phos-phoenolpyruvate carboxylase capacity and the sensitivity of the enzyme to the effectors L-malate (inhibitor) and glucose-6-phosphate (activator) were measured throughout the diurnal CAM cycle. In K. tubiflora, enzyme capacity was higher if measured at pH 7.0 than at pH 8.0 and displayed a rhythmical behavior with highest values at the end of the light period. As reported earlier, in K. blossfeldiana PEP-C capacity was higher during the night. It was more pronounced when plants were kept in CO2-free air during the dark period. In both plants, the sensitivity of the enzyme to the effectors showed very clear diurnal changes: inhibition by malate and activation by glucose-6-phosphate were strikingly higher during the day than during the night; the effect depended on PEP concentration. The changing activation of the enzyme by glucose-6-phos-phate reflects diurnal changes of the Km for PEP which was found to be higher during the day than during the night. Manipulations of malate accumulation by nocturnal application of CO2-free air did not influence these effects. The results are discussed in context with the metabolic control of CAM.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/1365-3040.ep11611032
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  • 3
    Electronic Resource
    Electronic Resource
    Induction of crown galls by Agrobacterium tumefaciens (strain C58) reverses assimilate translocation and accumulation in Kalanchoë daigremontiana (1992)
    Oxford, UK : Blackwell Publishing Ltd
    Plant, cell & environment 15 (1992), S. 0 
    Details
    ISSN: 1365-3040
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The mechanism of hormone-enhanced solute accumulation was investigated in crown galls of Kalanchoë diagremontiana, induced by Agrobacterium tumefaciens (C58). Electrophysiological, cytological staining, and 14CO2-tracer techniques were used. Intracellular auxin and zeatinriboside concentration increased in tumours by three and five times, respectively, compared with the mesophyll. In contrast, the electrical membrane potential difference, in particular the energy-dependent component across the plasma membrane of tumours was at least 60 mV smaller than that of mesophyll cells. The detection of functional sieve tubes, metabolically active companion cells and also developed xylem vessels correlated well with evidence for reversed, long-distance, 14C-labelled assimilate flow from CAM–performing mesophyll to sugar and potassium-accumulating tumours. The change in hormone production, encoded by the iaaM, iaaH and ipt T-DNA genes, apparently induced functioning vascular bundles and established a strong sink. From a comparison with tobacco suspension cells (SR1 and SR1-C58), the changes in the amino acid pattern in the mesophyll/tumour complex can be attributed to the enzymatic activities incited by the nos encoding gene. Differences in sugar and inorganic ion content were not apparent in the transformed suspension cells, indicating that the increase in extracellular concentration by enhanced phloem unloading may be the crucial factor for the pathological solute accumulation in the tumours.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-3040.1992.tb01485.x
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  • 4
    Electronic Resource
    Electronic Resource
    Properties of phosphoenol pyruvate carboxylase in Sedum species in relation to Crassulacean Acid Metabolism (CAM) (1979)
    Oxford, UK : Blackwell Publishing Ltd
    Plant, cell & environment 2 (1979), S. 0 
    Details
    ISSN: 1365-3040
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Abstract Parameters of Crassulacean Acid Metabolism (carbon isotope composition [δ13C values], diurnal acid cycles) were studied together with properties of phosphoenolpyruvate carboxylases (PEP-C) in eight species of the genus Sedum. The δ13C values indicate a considerable variability of CAM capacity among the species investigated. The spectra of organic acids were similar in all species. Malate, citrate, and isocitrate were the main components of the acid fraction. Quinic acid occurred only during the light period. Molecular weights of PEP-C were in the range of 160,000 and showed no correlation to CAM as indicated by the δ13C values. However, there were differences in the kinetic data of PEP-C. Sedum species with less negative δ13C (i.e. with high CAM capacity) have PEP-C with higher Vmax, higher Km (PEP) and higher sensitivity for malate inhibition.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-3040.1979.tb00776.x
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  • 5
    Electronic Resource
    Electronic Resource
    Structural and metabolic properties of green tissue cultures from a CAM plant, Kalanchoë blossfeldiana hybr. Montezuma (1987)
    Oxford, UK : Blackwell Publishing Ltd
    Plant, cell & environment 10 (1987), S. 0 
    Details
    ISSN: 1365-3040
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Abstract Crassulacean acid metabolism (CAM) was studied in mixotrophic callus tissue cultures of Kalanchoë blossfeldiana hybr. Montezuma and compared with plants propagated from the calli.The ultrastructural properties of the green callus cells are similar to mesophyll cells of CAM plants except that occasionally abnormal mitochondria were observed. There was permanent net CO2 output by the calli in light and darkness, which was lower in darkness than in light. The calli exhibited a diurnal rhythm of malic acid, with accumulation during the night and depletion during the day. 14C previously incorporated by dark CO2 fixation into malate was transferred upon subsequent illumination into end products of photosynthesis. All these data indicate that CAM operates in the calli tissue. The results revealed that the capacity for CAM is obviously lower in the calli compared with plantlets developing from the calli, or with ‘adult’ plants. The data suggest also that CAM in the calli was not limited by the activities of CAM enzymes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-3040.1987.tb01823.x
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  • 6
    Electronic Resource
    Electronic Resource
    Crassulacean acid metabolism in the epiphytic ferns Drymoglossum piloselloides and Pyrrosia longifolia: studies on responses to environmental signals (1986)
    Oxford, UK : Blackwell Publishing Ltd
    Plant, cell & environment 9 (1986), S. 0 
    Details
    ISSN: 1365-3040
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Abstract The paper reports the results of the comprehensive study of crassulacean acid metabolism in two epiphytic tropical ferns, Drymoglossum piloselloides and Pyrrosia longifolia. The plants were investigated under different light, temperature and water status. It was found that both species are obligate CAM plants. The diurnal acidity rhythm is due to the fluctuation in malic acid concentration, which accounts for the change in titratable acidity. Besides malic acid, shikimate and oxalate are found to be present, but not contributing to the CAM acid rhythm. The diurnal rhythm of malic acid content results in a corresponding rhythm in leaf water relations. Both ΦΦ and Φtotal, were lowest at the end of the night, i.e. when the level of malic acid was highest.The effects of temperature on CO2 exchange were inverse to those observed in other CAM plants. In both ferns studied, dark CO2 fixation increased when the night temperature was increased. Increase in day temperature reduced CO2 uptake during phase IV and during the following night. The observed responses of the ferns to temperature changes suggest that the in situ environmental conditions are optimal for their CAM performance. In weak light, the plants showed net CO2 output during the midday deacidification period. Increases in light intensity reduced such CO2 output.Under drought conditions, the CO2 exchange in the ferns was reduced to zero within 5–6 d, indicating that the ferns studied are more susceptible to water deficiency than other CAM plants. This could be due to a higher cuticular conductance for water.The results are discussed, in particular, in relation to CAM performance of epiphytes growing in the wet tropics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/1365-3040.ep11616291
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  • 7
    Electronic Resource
    Electronic Resource
    Comparative studies on immunological and molecular properties of phosphoenolpyruvate carboxylase in species of Sedum and Kalanchoë performing crassulacean acid metabolism (CAM) (1982)
    Oxford, UK : Blackwell Publishing Ltd
    Plant, cell & environment 5 (1982), S. 0 
    Details
    ISSN: 1365-3040
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Abstract. PEP-carboxylase was extracted and partially purified from nine species of the genus Sedum and three species of the genus Kalanchoe, all performing CAM. Immunological and molecular properties of these enzymes were compared. Molecular weight estimation with gradient slab gels showed identical molecular weights of about 232,000 for all PEP-carboxylases. Ouchlerlony double-diffusion analysis, immunotitralion and SDS polyacrylamide clectrophoresis indicated the presence of PEP-c dimers consisting of monomers of MW 105,000 and 115,000. A model of PEP-c substructure is proposed. The results are discussed in the context of CAM performance in the genus Sedum
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/1365-3040.ep11572356
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  • 8
    Electronic Resource
    Electronic Resource
    Immunological studies on phosphoenolpyruvate carboxylase in Sedum species with crassulacean acid metabolism or C3 photosynthesis (1980)
    Oxford, UK : Blackwell Publishing Ltd
    Plant, cell & environment 3 (1980), S. 0 
    Details
    ISSN: 1365-3040
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Abstract From Sedum morganianum, which is a plant species known to have constitutive crassulacean acid metabolism (CAM), phosphoenolpyruvate (PEP) carboxylase (E.C.4.1.1.31) has been extracted and purified by (NH4)2SC4 precipitation, ion exchange chromatography and gel electrophoresis. A specific antibody to this purified enzyme was obtained by immunization of a rabbit. This antibody was used to compare the antigen–antibody reaction of PEP-carboxylases prepared from other Sedum species including constitutive, facultative and non-CAM plants. The experiments revealed partial immunological indentity of PEP-carboxylases obtained from the different sources.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/1365-3040.ep11581821
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  • 9
    Electronic Resource
    Electronic Resource
    Phosphorylation - dephosphorylation process as a probable mechanism for the diurnal regulatory changes of phosphoenolpyruvate carboxylase in CAM plants
    Amsterdam : Elsevier
    Biochemical and Biophysical Research Communications 136 (1986), S. 151-159 
    Details
    ISSN: 0006-291X
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1016/0006-291X(86)90889-2
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  • 10
    Electronic Resource
    Electronic Resource
    Studies on malate fluxes in leaf slices of Bryophyllum daigremontianum - Verapamil-enhanced efflux out of the vacuole
    Amsterdam : Elsevier
    Plant Science Letters 1 (1973), S. 391-397 
    Details
    ISSN: 0304-4211
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1016/0304-4211(73)90103-X
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