Phytosterols, phytostanols, and their conjugates in foods: structural diversity, quantitative analysis, and health-promoting uses

Acknowledgements. Introduction. A: Environment. 1. Global impact of salinity and agricultural ecosystems M.G. Pitman, A. Lauchli. 2. Salinity in the soil environment K.K. Tanji. 3. Salinity, halophytes and salt affected natural ecosystems S.-W. Breckle. B: Organisms. 4. Adaptation of halophilic Archaea to life at high salt concentrations A. Oren. 5. Adaptation of the haloterant alga Dunaliella to high salinity U. Pick. 6. Mangroves U. Luttge. C: Mechanisms. 7. Ultrastructural effects of salinity in higher plants H.-W. Koyro. 8. Intra- and inter-cellular compartmentation of ions - a study in specificity and plasticity G. Wyn Jones, J. Gorham. 9. Salinity, osmolytes and compatible solutes D. Rhodes, et al. 10. Sodium-calcium interactions under salinity stress G.R. Cramer. 11. Salinity and nitrogen nutrition W.R. Ullrich. 12. Pressure probe measurements of the driving forces for water transport in intact higher plants: effects of transpiration and salinity U. Zimmermann, et al. 13. Salinity, growth and phytohormones R. Munns. 14. The adaptive potential of plant development: evidence from the response to salinity G.N. Amzallag. D: Photosynthesis. 15. Influence of salinity on photosynthesis of halophytes C.E. Lovelock, M.C. Ball. 16. Performance of plants with C4-carboxylation modes of photosynthesis under salinity U. Luttge. 17. Induction of Crassulacean acid metabolism by salinity -- molecular aspects H.J. Bohnert.E: Molecules. 18. Function of membrane transport systems under salinity: plasma membrane L. Reinhold, M. Guy. 19. Function of membrane transport systems under salinity: tonoplast M. Binzel, R. Ratajczak. 20. Genetics of salinity responses and plant breeding J. Gorham, G.Wyn Jones. 21. Halotolerance genes in yeast R. Serrano. 22. The long and winding road to haloterance genes A. Maggio, et al. Index.

Salinity : environment - plants - molecules

The influence of the Na and Le genes in peas on gibberellin (GA) levels and metabolism were examined by gas chromatographic-mass spectrometric analysis of extracts from a range of stem-length genotypes fed with [13C, 3H]GA20. The substrate was metabolised to [13C, 3H]GA1, [13C, 3H]GA8 and [13C, 3H]GA29 in the immature, expanding apical tissue of all genotypes carrying Le. In contrast, [13C, 3H]GA29 and, in one line, [13C, 3H]GA29-catabolite, were the only products detected in plants homozygous for the le gene. These results confirm that the Le gene in peas controls the 3β-hydroxylation of GA20 to GA1. Qualitatively the same results were obtained irrespective of the genotype at the Na locus. In all Na lines the [13C, 3H]GA20 metabolites were considerably diluted by endogenous [12C]GAs, implying that the metabolism of [13C, 3H]GA20 mirrored that of endogenous [12C]GA20. In contrast, the [13C, 3H]GA20 metabolites in na lines showed no dilution with [12C]GAs, confirming that the na mutation prevents the production of C19-GAs. Estimates of the levels of endogenous GAs in the apical tissues of Na lines, made from the 12C:13C isotope ratios and the radioactivity recovered in respective metabolites, varied between 7 and 40 ng of each GA per plant in the tissue expanded during the 5 d between treatment with [13C, 3H]GA20 and extraction. No [12C]GA1 and only traces of [12C]GA8 (in one line) were detected in the two Na le lines examined. These results are discussed in relation to recent observations on dwarfism in rice and maize.

Internode length in Pisum

http://aliesmaily17.persiangig.com/document/Citrus%20and%20salinity.pdf

Citrus and salinity

Several studies have provided new insights into the role of sphingolipid/sterol-rich domains so-called lipid rafts of the plasma membrane (PM) from mammalian cells, and more recently from leaves, cell cultures, and seedlings of higher plants. Here we show that lipid raft domains, defined as Triton X-100-insoluble membranes, can also be prepared from Medicago truncatula root PMs. These domains have been extensively characterized by ultrastructural studies as well as by analysis of their content in lipids and proteins. M. truncatula lipid domains are shown to be enriched in sphingolipids and Δ7-sterols, with spinasterol as the major compound, but also in steryl glycosides and acyl-steryl glycosides. A large number of proteins (i.e. 270) have been identified. Among them, receptor kinases and proteins related to signaling, cellular trafficking, and cell wall functioning were well represented whereas those involved in transport and metabolism were poorly represented. Evidence is also given for the presence of a complete PM redox system in the lipid rafts.

http://www.plantphysiol.org/content/plantphysiol/144/1/402.full.pdf

Characterization of Lipid Rafts from Medicago truncatula Root Plasma Membranes: A Proteomic Study Reveals the Presence of a Raft-Associated Redox System

/pdf/effects-of-free-sterols-steryl-ester-and-steryl-glycoside-on-26exly6hxi.pdf

Effects of Free Sterols, Steryl Ester, and Steryl Glycoside on Membrane Permeability

All membrane-containing fractions isolated from tobacco leaves contained free sterols, sterol glycosides, and sterol esters. The three sterol forms increased, on a dry weight basis, with a decrease in particle size. The supernatant fraction contained only trace amounts of sterol. The major sterols in all cellular fractions, in the order of decreasing amounts, were: stigmasterol, beta-sitosterol, campesterol, and cholesterol. The 500g pellet contained the largest percentage of free sterol, while the 46,000g pellet contained the largest percentage of esterified sterol. The individual sterol composition of the free sterol and sterol glycoside fraction was very similar; however, the composition of the sterol ester fraction varied widely among intracellular fraction. The intracellular distribution pattern of cholesterol-(14)C added to the isolation medium provided evidence that the intracellular sterol distribution pattern is not an artifact. These results support the suggestion that sterols in plant cells may have a physiological function associated with membranes.

Sterol Distribution in Intracellular Organelles Isolated from Tobacco Leaves

Alcohols and hydrogen peroxide altered the permeability of membranes of Beta vulgaris root cells. Generally alcohols increased the permeability of membranes without going through an induction period except methanol which required a 10- to 15-hour induction period. The membrane effect of methanol could be inhibited with CaCl(2), cholesterol, beta-sitosterol, and stigmasterol. Cholesterol was the most effective inhibitor, followed by beta-sitosterol and stigmasterol; and at the same concentration, the sterols were more effective than CaCl(2), the classic membrane stabilizer.Ergosterol increased the methanol-initiated betacyanin leakage. Since none of the tested sterols reversed the betacyanin efflux induced by hydrogen peroxide, the sterols do not apparently act as antioxidants. The results are explained in terms of sterol-phospholipid interaction, based on stereochemistry and charge distribution.

Effect of Sterols on the Permeability of Alcohol-Treated Red Beet Tissue

The identity, composition, and concentration of the total, free, esterified, and glycosidic sterol fractions were determined during germination of tobacco seeds. The total, free, and esterified sterols increased, with stigmasterol and campesterol accounting for most of the increase. Steryl glycosides decreased during germination, and stigmasteryl and sitosteryl glycosides showed the largest decrease. During germination, sitosterol was the major sterol in all fractions but stigmasterol and campesterol showed the greatest changes. The fatty acid composition of the steryl esters and acylated steryl glycosides most closely resembled the di- and triglycerides.

Sterol Changes during Germination of Nicotiana tabacum Seeds

Various sterols and related steroids were tested for their ability to influence ethanol-induced electrolyte leakage from Hordeum vulgare roots. Cholesterol had the greatest influence and, depending on concentration, it stimulated or inhibited the loss of electrolyte. Cholesterol, however, was ineffective if the roots were pretreated with ethanol. These data suggest that sterols protect rather than restore membrane structure. First, modifications in the cholesterol perhydrocyclopentanophenanthrene ring system suggest that at least one double bond is required for membrane activity. Second, increasing the bulkiness of the C(17) side chain of cholesterol, as shown with campesterol, stigmasterol, and sitosterol, decreased its activity. Apparently for maximum effectiveness the sterol molecule should have a relatively flat configuration. Third, the C(3)-hydroxyl group is required for membrane activity since cholesteryl methyl ether, cholest-5-ene-3beta-thiol and cholesteryl halogens were without activity. Exception to the foregoing rule was cholestane which was slightly active but which has neither a C(3)-hydroxyl group nor a double bond in the ring system.

/pdf/sterol-molecular-modifications-influencing-membrane-oc09cgmbzz.pdf

C. Grunwald

Papers

Effects of Free Sterols, Steryl Ester, and Steryl Glycoside on Membrane Permeability

Sterol Distribution in Intracellular Organelles Isolated from Tobacco Leaves

Effect of Sterols on the Permeability of Alcohol-Treated Red Beet Tissue

Sterol Changes during Germination of Nicotiana tabacum Seeds

Sterol molecular modifications influencing membrane permeability.