| 1. |
- Ekelund, K., et al.
(författare)
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Rectangular solid domains in ceramide-cholesterol monolayers - 2D crystals
- 2000
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Ingår i: Biochimica et Biophysica Acta - Biomembranes. - 0005-2736. ; 1464:1
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Tidskriftsartikel (refereegranskat)abstract
- Very small rectangular domains were observed by atomic force microscopy in binary monolayers of synthetic ceramides and cholesterol. When the cholesterol content is increased the domains are bigger although the rectangular shape is retained. The almost perfect shape of the domains indicates two-dimensional single ceramide crystals. Lipid domains in monolayers of this particular shape and size have to our knowledge not been reported in the literature previously.
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| 2. |
- Johansson, Ingela, et al.
(författare)
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The role of aquaporins in cellular and whole plant water balance
- 2000
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Ingår i: Biochimica et Biophysica Acta - Biomembranes. - 0005-2736. ; 1465:1-2, s. 324-342
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Forskningsöversikt (refereegranskat)abstract
- Aquaporins are water channel proteins belonging to the major intrinsic protein (MIP) superfamily of membrane proteins. More than 150 MIPs have been identified in organisms ranging from bacteria to animals and plants. In plants, aquaporins are present in the plasma membrane and in the vacuolar membrane where they are abundant constituents. Functional studies of aquaporins have hitherto mainly been performed by heterologous expression in Xenopus oocytes. A main issue is now to understand their role in the plant, where they are likely to be important both at the cellular and at the whole plant level. Plants contain a large number of aquaporin isoforms with distinct cell type- and tissue-specific expression patterns. Some of these are constitutively expressed, whereas the expression of others is regulated in response to environmental factors, such as drought and salinity. At the protein level, regulation of water transport activity by phosphorylation has been reported for some aquaporins.
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| 3. |
- Kanje, Martin, et al.
(författare)
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The effect of gossypol on fast axonal transport and microtubule assembly
- 1986
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Ingår i: Biochimica et Biophysica Acta - Biomembranes. - : Elsevier BV. - 0005-2736. ; 856:3, s. 437-442
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Tidskriftsartikel (refereegranskat)abstract
- Gossypol at micromolar concentrations (2 μM) was found to inhibit axonal transport and a microsomal ATPase activity in the frog sciatic nerve, although axonal microtubules and the neuronal content of AMP, ADP and ATP were not affected. At slightly higher concentrations (30-40 μM), gossypol also inhibited microtubule assembly and neuronal energy metabolism. Gossypol accumulated in the nerve and the results indicate that gossypol may act as a potent neurotoxin.
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| 4. |
- Saalman, Elisabeth, 1955, et al.
(författare)
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EFFECT OF 2.45 GHZ MICROWAVE-RADIATION ON PERMEABILITY OF UNILAMELLAR LIPOSOMES TO 5(6)-CARBOXYFLUORESCEIN - EVIDENCE OF NONTHERMAL LEAKAGE
- 1991
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Ingår i: Biochimica Et Biophysica Acta. - : Elsevier BV. - 0006-3002 .- 0005-2736. ; 1064:1, s. 124-130
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Tidskriftsartikel (refereegranskat)abstract
- The influence of 2.45 GHz microwave radiation on the membrane permeability of unilamellar liposomes was studied using the marker 5(6)-carboxyfluorescein trapped in phosphatidylcholine liposomes. The release of the fluorescent marker was followed by spectrofluorimetry after an exposure of 10 minutes to either microwave radiation or to heat alone of the liposome solutions. A significant increase of the permeability of carboxyfluorescein through the membrane was observed for the microwave-exposed samples compared to those exposed to normal heating only. Exposure to 2.45 GHz microwave radiation of liposomes has been previously found to produce increased membrane permeability as compared with heating. However, in contrast to previous studies, the observations reported here were made above the phase transition temperature of the lipid membrane. The experimental setup included monitoring of the temperature during microwave exposure simultaneously at several points in the solution volume using a fiberoptic thermometer. Possible mechanisms to explain the observations are discussed.
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| 5. |
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| 6. |
- Ickenstein, Ludger M., et al.
(författare)
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Disc formation in cholesterol-free liposomes during phase transition
- 2003
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Ingår i: Biochimica et Biophysica Acta - Biomembranes. - 0005-2736 .- 1879-2642. ; 1614:2, s. 135-138
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Tidskriftsartikel (refereegranskat)abstract
- Cryogenic transmission electron microscopy (cryo-TEM) images of lysolipid-containing thermosensitive liposomes (LTSL) revealed that open liposomes and bilayer discs appeared when liposomes were cycled through the gel (Lbeta') to liquid-crystalline (Lalpha) phase transition. The amount of bilayer discs generated was dependent on the combined presence of PEG-lipid and lysolipid in the membrane. We hypothesize that micelle-forming membrane components stabilize the rim of bilayer openings and membrane discs that form when liposomes are cycled through TC.
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| 7. |
- Magzoub, Mazin, et al.
(författare)
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Interaction and structure induction of cell-penetrating peptides in the presence of phospholipid vesicles
- 2001
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Ingår i: Biochimica et Biophysica Acta - Biomembranes. - 0005-2736 .- 1879-2642. ; 1512:1, s. 77-89
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Tidskriftsartikel (refereegranskat)abstract
- Certain short peptides, which are able to translocate across cell membranes with a low lytic activity, can be useful as carriers (vectors) for hydrophilic molecules. We have studied three such cell penetrating peptides: pAntp (‘penetratin’), pIsl and transportan. pAntp and pIsl originate from the third helix of homeodomain proteins (Antennapedia and Isl-1, respectively). Transportan is a synthetic chimera (galanin and mastoparan). The peptides in the presence of various phospholipid vesicles (neutral and charged) and SDS micelles have been characterized by spectroscopic methods (fluorescence, EPR and CD). The dynamics of pAntp were monitored using an N-terminal spin label. In aqueous solution, the CD spectra of the three peptides show secondary structures dominated by random coil. With phospholipid vesicles, neutral as well as negatively charged, transportan gives up to 60% α-helix. pAntp and pIsl bind significantly only to negatively charged vesicles with an induction of around 60% β-sheet-like secondary structure. With all three peptides, SDS micelles stabilize a high degree of α-helical structure. We conclude that the exact nature of any secondary structure induced by the membrane model systems is not directly correlated with the common transport property of these translocating peptides.
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| 8. |
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| 9. |
- Wasan, E K, et al.
(författare)
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A multi-step lipid mixing assay to model structural changes in cationic lipoplexes used for in vitro transfection
- 1999
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Ingår i: Biochimica et Biophysica Acta - Biomembranes. - 0005-2736 .- 1879-2642. ; 1461:1, s. 27-46
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Tidskriftsartikel (refereegranskat)abstract
- Formation of liposome/polynucleotide complexes (lipoplexes) involves electrostatic interactions, which induce changes in liposome structure. The ability of these complexes to transfer DNA into cells is dependent on the physicochemical attributes of the complexes, therefore characterization of binding-induced changes in liposomes is critical for the development of lipid-based DNA delivery systems. To clarify the apparent lack of correlation between membrane fusion and in vitro transfection previously observed, we performed a multi-step lipid mixing assay to model the sequential steps involved in transfection. The roles of anion charge density, charge ratio and presence of salt on lipid mixing and liposome aggregation were investigated. The resonance-energy transfer method was used to monitor lipid mixing as cationic liposomes (DODAC/DOPE and DODAC/DOPC; 1:1 mole ratio) were combined with plasmid, oligonucleotides or Na(2)HPO(4). Cryo-transmission electron microscopy was performed to assess morphology. As plasmid or oligonucleotide concentration increased, lipid mixing and aggregation increased, but with Na(2)HPO(4) only aggregation occurred. NaCl (150 mM) reduced the extent of lipid mixing. Transfection studies suggest that the presence of salt during complexation had minimal effects on in vitro transfection. These data give new information about the effects of polynucleotide binding to cationic liposomes, illustrating the complicated nature of anion induced changes in liposome morphology and membrane behavior.
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| 10. |
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