Biomaterial Database

Bilayer nanotubes and helical ribbons formed by hydrated galactosylceramides: acyl chain and headgroup effects. 1995

V S Kulkarni, and W H Anderson, and R E Brown

Hormel Institute, University of Minnesota, Austin 55912-3698, USA.

The molecular basis of bilayer tubule formation in hydrated galactosylceramide (GalCer) dispersions has been investigated by synthesizing different chain-pure GalCers and examining their aqueous mesomorphic phase structure by freeze fracture and negative-stain electron microscopy. Thermotropic characterization of the GalCer species by differential scanning calorimetry provided supplementary information that verified the phase state under which morphological observations were carried out. Under aqueous conditions and at room temperature, N-24:1 delta 15(cis) GalSph, the predominant monounsaturated, nonhydroxy acyl species of bovine brain GalCer (NFA-GalCer), formed cylindrical mesomorphic self-assemblies consisting almost exclusively of "nanotubes," i.e., lipid bilayer tubules of relatively uniform length and diameter (length, 250-400 nm; diameter, 25-30 nm). In contrast, N-24:0 GalSph, the major saturated, nonhydroxy acyl species of bovine brain GalCer, displayed no tendency to form these relatively small "nanotubes." Rather, N-24:0 GalSph formed larger, variable-length ribbon-like structures (length, 5,000-10,000 nm) that often appeared to undulate and, occasionally, appeared to be helically twisted. Interestingly, bovine brain GalCer, which contains high levels of the N-24:1 delta 15(cis) and N-24:0 species as well as 2-hydroxy acyl chains, formed multilamellar liposomes of variable size and showed little tendency to form cylindrical structures. This result suggested that changes to the polar interface/headgroup region imparted by the 2-hydroxy acyl species strongly influenced bilayer tubule and cylinder formation in GalCer. To define this influence more clearly, other sphingoid-based and glycerol-based lipids were investigated. Morphological characterization of N-24:1 delta 15(cis) sphingosylphosphorylcholine (24:1 SM) revealed no evidence of bilayer cylinder or tubule formation. Similar results were obtained with aqueous dispersions of 1-palmitoyl-2-nervonoyl phosphatidylcholine (16:0, 24:1 PC). Hence, the bulkier, more hydrated, zwitterionic phosphocholine headgroup inhibited the formation of bilayer nanotubes and cylinders under physiological saline conditions.

UI	MeSH Term	Description	Entries
D008051	Lipid Bilayers	Layers of lipid molecules which are two molecules thick. Bilayer systems are frequently studied as models of biological membranes.	Bilayers, Lipid,Bilayer, Lipid,Lipid Bilayer
D008081	Liposomes	Artificial, single or multilaminar vesicles (made from lecithins or other lipids) that are used for the delivery of a variety of biological molecules or molecular complexes to cells, for example, drug delivery and gene transfer. They are also used to study membranes and membrane proteins.	Niosomes,Transferosomes,Ultradeformable Liposomes,Liposomes, Ultra-deformable,Liposome,Liposome, Ultra-deformable,Liposome, Ultradeformable,Liposomes, Ultra deformable,Liposomes, Ultradeformable,Niosome,Transferosome,Ultra-deformable Liposome,Ultra-deformable Liposomes,Ultradeformable Liposome
D008854	Microscopy, Electron	Microscopy using an electron beam, instead of light, to visualize the sample, thereby allowing much greater magnification. The interactions of ELECTRONS with specimens are used to provide information about the fine structure of that specimen. In TRANSMISSION ELECTRON MICROSCOPY the reactions of the electrons that are transmitted through the specimen are imaged. In SCANNING ELECTRON MICROSCOPY an electron beam falls at a non-normal angle on the specimen and the image is derived from the reactions occurring above the plane of the specimen.	Electron Microscopy
D002152	Calorimetry, Differential Scanning	Differential thermal analysis in which the sample compartment of the apparatus is a differential calorimeter, allowing an exact measure of the heat of transition independent of the specific heat, thermal conductivity, and other variables of the sample.	Differential Thermal Analysis, Calorimetric,Calorimetric Differential Thermal Analysis,Differential Scanning Calorimetry,Scanning Calorimetry, Differential
D002417	Cattle	Domesticated bovine animals of the genus Bos, usually kept on a farm or ranch and used for the production of meat or dairy products or for heavy labor.	Beef Cow,Bos grunniens,Bos indicus,Bos indicus Cattle,Bos taurus,Cow,Cow, Domestic,Dairy Cow,Holstein Cow,Indicine Cattle,Taurine Cattle,Taurus Cattle,Yak,Zebu,Beef Cows,Bos indicus Cattles,Cattle, Bos indicus,Cattle, Indicine,Cattle, Taurine,Cattle, Taurus,Cattles, Bos indicus,Cattles, Indicine,Cattles, Taurine,Cattles, Taurus,Cow, Beef,Cow, Dairy,Cow, Holstein,Cows,Dairy Cows,Domestic Cow,Domestic Cows,Indicine Cattles,Taurine Cattles,Taurus Cattles,Yaks,Zebus
D005614	Freeze Fracturing	Preparation for electron microscopy of minute replicas of exposed surfaces of the cell which have been ruptured in the frozen state. The specimen is frozen, then cleaved under high vacuum at the same temperature. The exposed surface is shadowed with carbon and platinum and coated with carbon to obtain a carbon replica.	Fracturing, Freeze,Fracturings, Freeze,Freeze Fracturings
D005699	Galactosylceramides	Cerebrosides which contain as their polar head group a galactose moiety bound in glycosidic linkage to the hydroxyl group of ceramide. Their accumulation in tissue, due to a defect in beta-galactosidase, is the cause of galactosylceramide lipidosis or globoid cell leukodystrophy.	Galactocerebrosides,Galactosyl Ceramide,Galactosyl Ceramides,Galactosylceramide,Ceramide, Galactosyl,Ceramides, Galactosyl
D000818	Animals	Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA.	Animal,Metazoa,Animalia
D001703	Biophysics	The study of PHYSICAL PHENOMENA and PHYSICAL PROCESSES as applied to living things.	Mechanobiology
D014867	Water	A clear, odorless, tasteless liquid that is essential for most animal and plant life and is an excellent solvent for many substances. The chemical formula is hydrogen oxide (H2O). (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)	Hydrogen Oxide