The Experts below are selected from a list of 126 Experts worldwide ranked by ideXlab platform
A Blume - One of the best experts on this subject based on the ideXlab platform.
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Association of polyene antibiotics with sterol-free lipid membranes: I. Hydrophobic binding of Filipin to dimyristoylphosphatidylcholine bilayers.
Biochimica et biophysica acta, 1996Co-Authors: J. Milhaud, J.m Lancelin, B Michels, A BlumeAbstract:The interaction of Filipin III with multilamellar vesicles (MLV) of dimyristoylphosphatidylcholine (DMPC ) was studied by four complementary methods leading to the following results: (1) The modifications of the Filipin dichroic spectrum, by adding preformed fluid DMPC MLV, provide evidence of a saturable association with the stoichiometry DMPC/Filipin = 4.2 +/- 0.5, constant between 24 and 35 degrees Celsius. (2) Thermograms obtained by differential scanning calorimetry (DSC) on mixtures where Filipin is incorporated during the formation of MLV exhibit a high-temperature tail the more marked the higher the Filipin content and some structures at temperatures which depend on this content. The corresponding evolution with the temperature of the CD spectra reveals that the characteristic bound Filipin spectrum appears at the temperature at which a structure emerges. (3) Titration calorimetry measurements reveal that the association process is exothermic in the temperature range of the DSC endotherms in agreement with the Filipin-induced ordering of the lipid chains, previously established by 2H-NMR in the same temperature range (Milhaud et al.(1989) Eur. Biophys. J. 17, 151-158). A discussion of the relevancy of this exothermicity to the hydrophobic effect is developed by referring to the paper by Wimley and White ((1993) Biochemistry 32, 6307-6312).
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Association of polyene antibiotics with sterol-free lipid membranes: I. Hydrophobic binding of Filipin to dimyristoylphosphatidylcholine bilayers
Biochimica et Biophysica Acta (BBA) - Biomembranes, 1996Co-Authors: J. Milhaud, J.m Lancelin, B Michels, A BlumeAbstract:AbstractThe interaction of Filipin III with multilamellar vesicles (MLV) of dimyristoylphosphatidylcholine (DMPC) was studied by four complementary methods leading to the following results: (1) The modifications of the Filipin dichroic spectrum, by adding preformed fluid DMPC MLV, provide evidence of a saturable association with the stoichiometry DMPC/Filipin = 4.2 ± 0.5, constant between 24 and 35°C. (2) Thermograms obtained by differential scanning calorimetry (I)SO on mixtures where Filipin is incorporated during the formation of MLV exhibit a high-temperature tail the more marked the higher the Filipin content and some structures at temperatures which depend on this content. The corresponding evolution with the temperature of the CD spectra reveals that the characteristic bound Filipin spectrum appears at the temperature at which a structure emerges. (3) Titration calorimetry measurements reveal that the association process is exothermic in the temperature range of the DSC endotherms in agreement with the Filipin-induced ordering of the lipid chains, previously established by 2H-NMR in the same temperature range (Milhaud et al. (1989) Eur. Biophys. J. 17, 151–158). A discussion of the relevancy of this exothermicity to the hydrophobic effect is developed by referring to the paper by Wimley and White ((1993) Biochemistry 32, 6307–6312)
W. De Souza - One of the best experts on this subject based on the ideXlab platform.
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distribution of Filipin sterol complexes in the plasma membrane of stallion spermatozoa during the epididymal maturation process
Molecular Reproduction and Development, 1991Co-Authors: W. De SouzaAbstract:The presence and distribution of cholesterol in mature and immature epididymal spermatozoa was analyzed using Filipin as a cytochemical tool in freeze-fracture replicas and thin section preparations. The polyenic-antibiotic Filipin formed complexes with 3, beta -OH sterols, producing characteristic protrusions, or pits, that were heterogeneously distributed in the plasma membrane of stallion spermatozoa, revealing a specific organization in a functionally specialized area of the gamete. The acrosomal region of the sperm head presented a significantly higher density of Filipin sterol complexes than the postacrosomal region, which was usually free of these complexes. The plasma membrane of the flagellum also showed Filipin sterol complexes randomly distributed in freeze-fracture replicas. The strong Filipin labeling observed in the membrane of spermatozoa obtained from the caput region of the epididymis decreased significantly during epididymal passage. The significance of these changes is not completely understood, but they might contribute to establishing the molecular organization necessary for sperm transit and storage in the epididymis as well as to development of motile spermatozoa that are able to fertilize the oocyte and induce normal embryonic development.
Françoise Plas Simon - One of the best experts on this subject based on the ideXlab platform.
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Plasma membrane sterol complexation, generated by Filipin, triggers signaling responses in tobacco cells
Biochimica et Biophysica Acta:Biomembranes, 2010Co-Authors: Laurent Bonneau, Patricia Gerbeau-pissot, Dominique Thomas, Christophe Der, Jeannine Lherminier, Stephane Bourque, Yann Roche, Françoise Plas SimonAbstract:The effects of changes in plasma membrane (PM) sterol lateral organization and availability on the control of signaling pathways have been reported in various animal systems, but rarely assessed in plant cells. In the present study, the pentaene macrolide antibiotic Filipin III, commonly used in animal systems as a sterol sequestrating agent, was applied to tobacco cells. We show that Filipin can be used at a non-lethal concentration that still allows an homogeneous labeling of the plasma membrane and the formation of Filipin-sterol complexes at the ultrastructural level. This Filipin concentration triggers a rapid and transient NADPH oxidase-dependent production of reactive oxygen species, together with an increase in both medium alkalinization and conductivity. Pharmacological inhibition studies suggest that these signaling events may be regulated by phosphorylations and free calcium. By conducting FRAP experiments using the di-4-ANEPPDHQ probe and spectrofluorimetry using the Laurdan probe, we provide evidence for a Filipin-induced increase in PM viscosity that is also regulated by phosphorylations. We conclude that Filipin triggers ligand-independent signaling responses in plant cells. The present findings strongly suggest that changes in PM sterol availability could act as a sensor of the modifications of cell environment in plants leading to adaptive cell responses through regulated signaling processes.
J. Milhaud - One of the best experts on this subject based on the ideXlab platform.
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Association of polyene antibiotics with sterol-free lipid membranes: I. Hydrophobic binding of Filipin to dimyristoylphosphatidylcholine bilayers.
Biochimica et biophysica acta, 1996Co-Authors: J. Milhaud, J.m Lancelin, B Michels, A BlumeAbstract:The interaction of Filipin III with multilamellar vesicles (MLV) of dimyristoylphosphatidylcholine (DMPC ) was studied by four complementary methods leading to the following results: (1) The modifications of the Filipin dichroic spectrum, by adding preformed fluid DMPC MLV, provide evidence of a saturable association with the stoichiometry DMPC/Filipin = 4.2 +/- 0.5, constant between 24 and 35 degrees Celsius. (2) Thermograms obtained by differential scanning calorimetry (DSC) on mixtures where Filipin is incorporated during the formation of MLV exhibit a high-temperature tail the more marked the higher the Filipin content and some structures at temperatures which depend on this content. The corresponding evolution with the temperature of the CD spectra reveals that the characteristic bound Filipin spectrum appears at the temperature at which a structure emerges. (3) Titration calorimetry measurements reveal that the association process is exothermic in the temperature range of the DSC endotherms in agreement with the Filipin-induced ordering of the lipid chains, previously established by 2H-NMR in the same temperature range (Milhaud et al.(1989) Eur. Biophys. J. 17, 151-158). A discussion of the relevancy of this exothermicity to the hydrophobic effect is developed by referring to the paper by Wimley and White ((1993) Biochemistry 32, 6307-6312).
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Association of polyene antibiotics with sterol-free lipid membranes: I. Hydrophobic binding of Filipin to dimyristoylphosphatidylcholine bilayers
Biochimica et Biophysica Acta (BBA) - Biomembranes, 1996Co-Authors: J. Milhaud, J.m Lancelin, B Michels, A BlumeAbstract:AbstractThe interaction of Filipin III with multilamellar vesicles (MLV) of dimyristoylphosphatidylcholine (DMPC) was studied by four complementary methods leading to the following results: (1) The modifications of the Filipin dichroic spectrum, by adding preformed fluid DMPC MLV, provide evidence of a saturable association with the stoichiometry DMPC/Filipin = 4.2 ± 0.5, constant between 24 and 35°C. (2) Thermograms obtained by differential scanning calorimetry (I)SO on mixtures where Filipin is incorporated during the formation of MLV exhibit a high-temperature tail the more marked the higher the Filipin content and some structures at temperatures which depend on this content. The corresponding evolution with the temperature of the CD spectra reveals that the characteristic bound Filipin spectrum appears at the temperature at which a structure emerges. (3) Titration calorimetry measurements reveal that the association process is exothermic in the temperature range of the DSC endotherms in agreement with the Filipin-induced ordering of the lipid chains, previously established by 2H-NMR in the same temperature range (Milhaud et al. (1989) Eur. Biophys. J. 17, 151–158). A discussion of the relevancy of this exothermicity to the hydrophobic effect is developed by referring to the paper by Wimley and White ((1993) Biochemistry 32, 6307–6312)
Markus Grebe - One of the best experts on this subject based on the ideXlab platform.
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Fluorescent in situ visualization of sterols in Arabidopsis roots
Nature Protocols, 2011Co-Authors: Yohann Boutté, Markus GrebeAbstract:Sterols are eukaryotic membrane components with crucial roles in diverse cellular processes. Elucidation of sterol function relies on development of tools for in situ sterol visualization. Here we describe protocols for in situ sterol localization in Arabidopsis thaliana root cells, using Filipin as a specific probe for detection of fluorescent Filipin-sterol complexes. Currently, Filipin is the only established tool for sterol visualization in plants. Filipin labeling can be performed on aldehyde-fixed samples, largely preserving fluorescent proteins and being compatible with immunocytochemistry. Filipin can also be applied for probing live cells, taking into account the fact that it inhibits sterol-dependent endocytosis. The experimental procedures described are designed for fluorescence detection by confocal laser-scanning microscopy with excitation of Filipin-sterol complexes at 364 nm. The protocols require 1 d for sterol covisualization with fluorescent proteins in fixed or live roots and 2 d for immunocytochemistry on whole-mount roots.