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| 2. |
- Lundberg, Peter, et al.
(författare)
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Permeabilization of Plant Cells: 31P NMR Studies of the Permeability of the Tonoplast
- 1986
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Ingår i: Plant Cell Reports. - : Springer. - 0721-7714 .- 1432-203X. ; 5, s. 13-16
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Tidskriftsartikel (refereegranskat)abstract
- A suspension culture of Catharanthus roseus has been used to study the permeability of cell membranes after treatment with various concentrations of a permeabilizing agent (DMSO). The uptake and release (after permeabilization) of inorganic phosphate (Pi) by cells have been investigated by 32P radiotracer and non-invasive phosphorus-31 NMR experiments. These studies have demonstrated that measurements of the Pi-efflux from plant cells provide a reliable measure of the permeability of the tonoplast.
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| 3. |
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| 4. |
- Bramble, J L, et al.
(författare)
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Calcium and Phosphate Effects on Growth and Alkaloid Production in Coffea arabica: Experimental Results and Mathematical Model.
- 1991
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Ingår i: Biotechnology and Bioengineering. - : Wiley. - 0006-3592 .- 1097-0290. ; 37:9, s. 859-868
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Tidskriftsartikel (refereegranskat)abstract
- Plant, mammalian, and microbial cells are commonly immobilized in calcium alginate gels for the production of valuable secondary metabolites. However, calcium ions are known to inhibit growth in various type of cells, and calcium is an integral part of such gels. Therefore, an investigation was conducted to evaluate the effect of calcium on the growth and alkaloid production of a model cell-line, Coffea arabica, in suspension culture before attempting to immobilize such cells in alginate. A kinetic model was then developed from the results to describe cell growth and alkaloid production and the mechanism by which calcium influences these variables. In addition, it was observed that there was a characteristic relationship between the concentration of calcium in the external medium and the concentration of extracellular and intracellular phosphate. The intracellular phosphate level was, in turn, related to the production of alkaloids. Using these results, a dynamic mathematical model of cell growth and alkaloid production was developed based on the proposed roles of calcium and phosphate. The model showed satisfactory agreement with three sets of experiments at different calcium concentrations. A possible linkage between the calcium and phosphate results is postulated based on the limited solubility of calcium phosphate.
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| 5. |
- Bramble, J L, et al.
(författare)
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Plant Cell Culture using a Novel Bioreactor: The Magnetically Stabilized Fluidized Bed
- 1990
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Ingår i: Biotechnology progress (Print). - : Wiley. - 8756-7938 .- 1520-6033. ; 6:6, s. 452-457
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Tidskriftsartikel (refereegranskat)abstract
- A novel bioreactor using magnetically stabilized fluidized bed (MSFB) technology has been developed that has certain advantages for cultivating cells continuously. In this system, the cells are protected from shear and are constrained to move through the fermenter in lock-step fashion by being immobilized in calcium alginate beads. The MSFB permits good mass transfer, minimizes particle collisions, and allows for the production of cells while maintaining a controlled cell residence time. Details of the experimental system are described. In addition, the experimental performance of an MSFB used to grow plant cells in batch mode is compared to the results obtained in shake flask culture.
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| 6. |
- Brodelius, Peter, et al.
(författare)
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A Phosphorus-31 Nuclear Magnetic Resonance Study of Phosphate Uptake and Storage in Cultured Catharanthus roseus and Daucus carota Plant Cells
- 1985
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Ingår i: Journal of Biological Chemistry. - 0021-9258 .- 1083-351X. ; 260, s. 3556-3560
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Tidskriftsartikel (refereegranskat)abstract
- High resolution "P NMR spectra (103.2 MHz) ofoxygenated Catharanthus roseu8 and Daucus carotacells grown in suspension cultures were obtained usinga solenoidal perfusion probe. The spectra showed resonancesfor various phosphorylated metabolites suchas ATP, ADP, NAD(P)(H), nucleoside diphosphoglucose,and sugar phosphates. The relative levels ofthe phosphorylated metabolites remained constantthroughout the growth curve. No resonances for storagecompounds such as polyphosphates, pyrophosphate,or phytates were observed. Two resolved resonancesfor Pi indicated an intracellular pH of 7.3 and5.7 (or below) for the cytoplasm and vacuoles, respectively.The time course of Pi uptake and storage duringgrowth in fresh culture medium was followed by studyingthe level of vacuolar Pi with 31PN MR (145.7 MHz).Simultaneously, the level of Pi in the culture mediumwas followed with radioactive s2P. C. roseus quicklytakes up all the Pi from the culture medium (maximumrate 1.7 pmol min" g" (dry weight of cells)). The Pi isfirst stored in the vacuoles; subsequently, one part ofthis pool is used to keep a constant cytoplasmic Pi levelwhile another part is apparently accumulated as anNMR invisible Pi store, probably in another cell organelle.In contrast, D. carota does not accumulate Pi inthe vacuoles and consequently it takes up Pi from themedium at a much slower rate (0.05 pmol min" g"(dry weight of cells)).
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| 7. |
- Brodelius, Peter, et al.
(författare)
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A Procedure for the Determination of Optimal Chitosan Concentrations for Elicitation of Cultured Plant Cells.
- 1989
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Ingår i: Phytochemistry. - 0031-9422 .- 1873-3700. ; 28:10, s. 2651-2654
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Tidskriftsartikel (refereegranskat)abstract
- An experimental method for determination of the optimum chitosan concentration for elicitation of plant cell suspension cultures is presented. The procedure, which is based on measurements of the conductivity of the culture medium after addition of chitosan, has been applied to suspension cultures of Nicotiana tabacum and Eschscholtzia californica. Increased conductivity of the medium (due to permeabilization of the cells) results in decreased secondary product formation and cell growth. Maximum product formation is observed for cells elicited with the highest chitosan concentration which does not affect membrane permeability.
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| 8. |
- Brodelius, Peter, et al.
(författare)
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Determination of Dissociation Constants for Binary Dehydrogenase-Coenzyme Complexes by (Bio)Affinity Chromatography on an Immobilized AMP-Analogue
- 1976
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Ingår i: Analytical biochemistry. - : Elsevier BV. - 0003-2697. ; 72:1-2, s. 629-636
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Tidskriftsartikel (refereegranskat)abstract
- Various alcohol and lactate dehydrogenases were adsorbed to an affinity column of immobilized N6-(6-aminohexyl)-AMP and subsequently eluted with gradients of coenzymes or coenzyme fragments. A linear relation was observed between the eluting concentration of nucleotide and the reported dissociation constants for the corresponding binary enzyme-nucleotide complexes. This relation has been utilized to determine unknown dissociation constants by affinity chromatography. The method presented can also be utilized for the estimation of dissociation constants betweendehydrogenases and coenzyme analogues.
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| 9. |
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| 10. |
- Brodelius, Peter
(författare)
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Enzyme assays
- 1991
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Ingår i: Current Opinion in Biotechnology. - 0958-1669 .- 1879-0429. ; 2:1, s. 23-29
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Tidskriftsartikel (refereegranskat)abstract
- The past year or so has seen the development of new enzyme assays, as well as the improvement of existing ones. Assays are becoming more rapid and sensitive as a result of modifications such as amplification of the enzyme product(s). Recombinant DNA technology is now being recognized as a particularly useful tool in the search for improved assay systems.
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