scholarly journals THE ULTRASTRUCTURE OF LIPID-DEPLETED ROD PHOTORECEPTOR MEMBRANES

1974 ◽  
Vol 63 (2) ◽  
pp. 587-598 ◽  
Author(s):  
Izhak Nir ◽  
Michael O. Hall
Keyword(s):  
Lipid Extraction ◽  
Fatty Acid Analysis ◽  
Major Protein ◽  
Rod Photoreceptor ◽  
Thin Sections ◽  
Retinal Rod ◽  
Layer Chromatography ◽  
Chloroform Methanol ◽  
Photoreceptor Membranes

The structure of lipid-depleted retinal rod photoreceptor membranes was studied by means of electron microscopy. Aldehyde-fixed retinas were exhaustively extracted with acetone, chloroform-methanol, and acidified chloroform-methanol. The effect of prefixation on the extractability of lipids was evaluated by means of thin-layer chromatography and fatty acid analysis. Prefixation with glutaraldehyde rendered 38% of the phospholipids unextractable, while only 7% were unextractable after formaldehyde fixation. Embedding the retina in a lipid-retaining, polymerizable glutaraldehyde-urea mixture allows a comparison of the interaction of OsO4 with lipid-depleted membranes and rod disk membranes which contain all their lipids. A decrease in electron density and a deterioration of membrane fine structure in lipid-depleted tissue are correlated with the extent of lipid extraction. These observations are indicative of the role of the lipid bilayer in the ultrastructural visualization of membrane structure with OsO4. Negatively stained thin sections of extracted tissue reveal substructures in the lipid-depleted rod membranes. These substructures are probably the opsin molecules which are the major protein component of retinal rod photoreceptor membranes.

scholarly journals Sensitive light scattering probe of enzymatic processes in retinal rod photoreceptor membranes

1984 ◽  
Vol 81 (3) ◽  
pp. 743-747 ◽  
Author(s):  
J. W. Lewis ◽  
J. L. Miller ◽  
J. Mendel-Hartvig ◽  
L. E. Schaechter ◽  
D. S. Kliger ◽  
...  
Keyword(s):  
Light Scattering ◽  
Rod Photoreceptor ◽  
Retinal Rod ◽  
Photoreceptor Membranes

Lipids of antibiotic-resistant and -susceptible members of the Enterobacteriaceae

1977 ◽  
Vol 23 (8) ◽  
pp. 1045-1051 ◽  
Author(s):  
William J. Suling ◽  
William M. O'Leary
Keyword(s):  
Fatty Acids ◽  
Fatty Acid Analysis ◽  
Lower Amount ◽  
Bacterial Strains ◽  
Antibiotic Resistant ◽  
Cyclopropane Fatty Acids ◽  
Resistant Strains ◽  
Lower Ratio ◽  
Layer Chromatography ◽  
Chloroform Methanol

Lipids of antibiotic-resistant and related -susceptible strains of the Enterobacteriaceae were extracted with chloroform–methanol and characterized by thin-layer chromatography, densitometry, and fatty acid analysis using gas chromatography. Quantitative differences which correlated with antibiotic resistance existed among the phospholipids and fatty acids. A relatively higher concentration of a ninhydrin-positive phospholipid concomitant with a lower amount of phosphatidylethanolamine was observed in antibiotic-resistant strains of Serratia marcescens. Bacterial strains which harbored R-factor 222 had a higher ratio of phosphatidylglycerol to diphosphatidylglycerol than their respective parent strains while those strains which were resistant to the polymyxins had a lower ratio of these phospholipids. Differences in the relative amounts of certain unsaturated and cyclopropane fatty acids were observed between susceptible and resistant strains. Such differences, however, were dependent upon a particular genus and species.

Degradative Wool Shrinkproofing Processes: Part II: Lipid Modification

1992 ◽  
Vol 62 (12) ◽  
pp. 704-709 ◽  
Author(s):  
L. Coderch ◽  
C. Soriano ◽  
A. Pinazo ◽  
J. L. Parra ◽  
P. Erra
Keyword(s):  
Lipid Extraction ◽  
Polar Lipids ◽  
Flame Ionization Detection ◽  
Lipid Modification ◽  
Lipid Modifications ◽  
Flame Ionization ◽  
Layer Chromatography ◽  
Chloroform Methanol ◽  
Treatment Medium ◽  
Water Dissolution

We have investigated lipid modifications produced by some degradative shrinkproofing processes. Using thin-layer chromatography with flame ionization detection, we have determined the composition of the lipids extracted from untreated and treated wools with chloroform/methanol azeotrope. The treatment medium modifies the CMC, facilitating penetration of the reactive agents. In the case of formic acid, the swelling of the fibers and modification of the intercellular cement are reflected in a higher subsequent lipid extraction, mainly sterols and polar lipids. In the case of isopropanol/water, dissolution of a large amount of the lipids during the treatment is reflected in the smaller amount of lipids extracted from these treated fibers, the amounts of free fatty acids, sterols, and polar lipids being markedly reduced.

A Role of Cytidine 5′-Diphosphocholine in the Transfer of N-Acetylglncosamine from UDP-N-acetylglucosamine into Endogenous Acceptor Lipids and Proteins in Rat and Hen Liver Microsomes

1972 ◽  
Vol 50 (10) ◽  
pp. 1094-1108 ◽  
Author(s):  
Sailen Mookerjea ◽  
D. E. C. Cole ◽  
A. Chow ◽  
Pamela Letts
Keyword(s):  
Thin Layer ◽  
Acid Hydrolysis ◽  
Divalent Cations ◽  
Liver Microsomes ◽  
Deae Cellulose ◽  
Lipid Product ◽  
Layer Chromatography ◽  
Chloroform Methanol ◽  
Temperature Optima

Evidence is presented for the transfer of N-acetylglucosamine into lipids by cell-free preparations of rat and hen livers. CDP-choline stimulates the formation of this carbohydrate–lipid product. Triton is required for this reaction and for promoting the CDP-choline effect. Requirements for divalent cations, Triton, pH, and temperature optima have been established. The total microsomes, rough microsomes, and Golgi-depleted fractions of rat liver, but not the Golgi-rich membrane fractions, are active in the formation of carbohydrate–lipid product and are responsive to CDP-choline.The labeled lipid–carbohydrate product is stable to mild alkali but labile to mild acid hydrolysis. Following acid hydrolysis radioactive N-acetylglucosamine was recovered by thin-layer electrophoresis. The radioactive lipid has been separated by thin-layer chromatography. Autoradiography of thin-layer plates showed two or three (only in presence of CDP-choline) radioactive bands. Over 90% of the labeled carbohydrate–lipid product has been isolated by DEAE-cellulose acetate column chromatography by elution with ammoniacal chloroform–methanol mixture.A study of simultaneous incorporation of N-acetylglucosamine-1-14C into lipids and proteins in the microsomes showed that the peak incorporation into lipids and into proteins was 5 and 30 min, respectively. This suggests that N-acetylglucosamine incorporation into protein may be mediated through a lipid–carbohydrate intermediate.

The effect of lipid extraction on electron-microscopic images of plant membranes

1973 ◽  
Vol 51 (6) ◽  
pp. 1221-1229 ◽  
Author(s):  
Elizabeth S. Swanson ◽  
William W. Thomson ◽  
J. Brian Mudd
Keyword(s):  
Structural Integrity ◽  
Lipid Extraction ◽  
Glutaraldehyde Fixation ◽  
Specific Lipids ◽  
Electron Microscopic ◽  
Plant Membranes ◽  
Acetone Extracts ◽  
Layer Chromatography ◽  
Density Pattern

An evaluation was made of the role of lipids in electron-microscopic membrane images of plant cells by comparing extracted lipids with changes in the ultrastructural membrane images. Lipids were extracted from tobacco leaves with a series of acetone concentrations. In a parallel series, glutaraldehyde fixation preceded lipid extraction. Thin-layer chromatography of the acetone extracts showed no major difference in the lipids extracted with and without glutaraldehyde fixation, but different concentrations of acetone removed specific lipids. Electron micrographs of tissues not previously fixed with glutaraldehyde showed a disruption of all membrane images at acetone concentrations greater than 30%. From these studies it appears that lipids are involved in the formation of electron-microscopic membrane images, but to a different degree in the various membranes. The general form of mitochondria and chloroplast grana was not dependent upon lipid, though lipid was required for the typical density pattern of the granal partitions. The bounding membranes of the mitochondria and chloroplasts were lost with extraction of galactolipids, sulfolipids, and phospholipids. The plasmalemma, tonoplast, and microbody membranes lost their typical density pattern and their structural integrity with the extraction of phospholipids.

The Nature of Rapidly Extracted Phycocyanin from the Blue-Green Alga Plectonema Boryanum

1971 ◽  
Vol 29 ◽  
pp. 366-367
Author(s):  
M. Kessel ◽  
R. MacColl
Keyword(s):  
Self Assembly ◽  
Analytical Ultracentrifugation ◽  
Uranyl Acetate ◽  
The Self ◽  
Major Protein ◽  
Subunit Structure ◽  
Blue Green Alga ◽  
Thin Sections ◽  
Blue Green Algae ◽  
Cacodylate Buffer

The major protein of the blue-green algae is the biliprotein, C-phycocyanin (Amax = 620 nm), which is presumed to exist in the cell in the form of distinct aggregates called phycobilisomes. The self-assembly of C-phycocyanin from monomer to hexamer has been extensively studied, but the proposed next step in the assembly of a phycobilisome, the formation of 19s subunits, is completely unknown. We have used electron microscopy and analytical ultracentrifugation in combination with a method for rapid and gentle extraction of phycocyanin to study its subunit structure and assembly.To establish the existence of phycobilisomes, cells of P. boryanum in the log phase of growth, growing at a light intensity of 200 foot candles, were fixed in 2% glutaraldehyde in 0.1M cacodylate buffer, pH 7.0, for 3 hours at 4°C. The cells were post-fixed in 1% OsO4 in the same buffer overnight. Material was stained for 1 hour in uranyl acetate (1%), dehydrated and embedded in araldite and examined in thin sections.

A High-Throughput Liposome Substrate Assay with Automated Lipid Extraction Process for PI 3-Kinase

2008 ◽  
Vol 13 (9) ◽  
pp. 906-911 ◽  
Author(s):  
Trupti Lingaraj ◽  
John Donovan ◽  
Zhi Li ◽  
Ping Li ◽  
Amanda Doucette ◽  
...  
Keyword(s):  
High Throughput ◽  
Lipid Extraction ◽  
Extraction Process ◽  
Enzyme Mechanism ◽  
Class I ◽  
Lipid Kinase ◽  
Chromatography Analysis ◽  
Regulate Cell Growth ◽  
Lipid Kinases ◽  
Layer Chromatography

The signaling pathways involving lipid kinase class I phosphatidylinositol 3-kinases (PI 3-kinases) regulate cell growth, proliferation, and survival. Class I PI 3-kinases catalyze the conversion of PI (4,5)P2 to PI (3,4,5)P3, which acts as a lipid second messenger to activate mitogenic signaling cascades. Recently, p110α, a class IA PI 3-kinase, was found to be mutated frequently in many human cancers. Therefore, it is increasingly studied as an anticancer drug target. Traditionally, PI 3-kinase activities have been studied using liposome substrates. This method, however, is hampered significantly by the labor-intensive manual lipid extraction followed by a low-throughput thin-layer chromatography analysis. The authors describe a high-throughput liposome substrate-based assay based on an automated lipid extraction method that allows them to study PI 3-kinase enzyme mechanism and quantitatively measure inhibitor activity using liposome substrates in a high-throughput mode. This improved assay format can easily be extended to study other classes of phosphoinositide lipid kinases. ( Journal of Biomolecular Screening 2008:906-911)

Sign in / Sign up

Export Citation Format

Share Document