| 1. |
- 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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| 2. |
- Hellstrand, Per, et al.
(författare)
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Phosphagens and intracellular pH in intact rabbit smooth muscle studied by 31P-NMR
- 1985
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Ingår i: American Journal of Physiology: Cell Physiology. - 1522-1563. ; 248:3 Pt 1, s. 320-329
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Tidskriftsartikel (refereegranskat)abstract
- Phosphorus-31 nuclear magnetic resonance (NMR) spectra (103.2 MHz) were obtained from rabbit portal vein, urinary bladder, and taenia coli smooth muscle. The muscles were mounted isometrically as strips in a horizontal probe and superfused with oxygenated medium at 23 degrees C. Under these conditions the preparations could remain in a stable metabolic state for at least 24 h. The resonances observed represented phosphocreatine (PC), adenosine triphosphate (ATP), and phosphomonoester. The PC-ATP ratio in relaxed preparations was approximately 1.9 (bladder) and 1.4 (taenia coli), approximately consistent with chemical analysis of tissue extracts by isotachophoresis. However, the levels of adenosine diphosphate (ADP) and inorganic phosphate (Pi) were considerably lower as estimated by NMR, suggesting intracellular compartmentalization. Contraction for 30 min in high-K+ medium caused a reversible 10-30% decline of PC but no change in ATP. Intracellular pH was 7.0 +/- 0.1 and was unchanged by contraction or inhibition of tissue respiration by cyanide. Treatment with 2-deoxyglucose resulted in accumulation of 2-deoxyglucose 6-phosphate, verifying the pH assignment. However, the phosphomonoester resonance of normal spectra is not glucose 6-phosphate. Treatment with Mg2+-free, high-Mg2+ (10 mM), or hyperosmotic media did not alter the Mg2+ saturation of ATP. The results obtained by the nontissue-destructive 31P-NMR measurements are consistent with the view that metabolic steady-state conditions are maintained during contraction in the smooth muscle.
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| 3. |
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| 4. |
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| 5. |
- Lundberg, Peter, et al.
(författare)
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NMR as a Noninvasive Tool in Meat Research
- 1987
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Ingår i: Annals of the New York Academy of Sciences. - : John Wiley & Sons. - 0077-8923 .- 1749-6632. ; 508, s. 516-522
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Tidskriftsartikel (refereegranskat)abstract
- NMR has been used for some time for in vivo measurements of biological tissues and has established itself as a valuable and complementary method to be used in parallel with traditional extraction methods. To date most attention has been paid to problems such as central biochemical pathways, energy metabolism in simple organisms and organs, and of course to problems encountered in medicine. There has been relative little interest in applying NMR to problems in food technology, even if these questions can have a tremendous impact on everyday life. Following a suggestion by Gadian,' we show here that multinuclear metabolic NMR is a useful method for studying post-mortem events in carcasses of slaughtered animals.The treatment and storage of carcasses during the first hours after slaughter is of extreme importance for the final quality and tenderness of the meat. Mistreatment can cause large economical losses and waste of valuable food. For example, in order to reduce the risk of bacterial infections one would like to cool down a carcass as soon as possible. Nevertheless, if a muscle is cooled down below 15OC before the postmortem metabolism is completed it may shorten dramatically thus decreasing the tenderness of the meat.' Therefore it is important to measure the rates of postmortem metabolism and to study the efficiency of methods that are aimed at speeding up this process.
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| 6. |
- 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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