scholarly journals SELECTIVE RELEASE OF CONTENT FROM MICROSOMAL VESICLES WITHOUT MEMBRANE DISASSEMBLY

1973 ◽  
Vol 58 (2) ◽  
pp. 436-462 ◽  
Author(s):  
Gert Kreibich ◽  
Pascale Debey ◽  
David D. Sabatini
Keyword(s):  
Gradient Centrifugation ◽  
Membrane Vesicles ◽  
Sucrose Density Gradient ◽  
Transport Systems ◽  
Secretory Proteins ◽  
Sucrose Density Gradient Centrifugation ◽  
Detergent Concentration ◽  
Doc Concentration ◽  
Microsomal Membranes

Rat liver rough microsomes treated with a series of desoxycholate (DOC) concentrations from 0.003 to 0.4% were analyzed by isopycnic sucrose density gradient centrifugation in media containing high or low salt concentrations. Tritium-labeled precursors administered in vivo were used as markers for ribosomes (orotic acid, 40 h), phospholipids (choline, 4 h), membrane proteins (leucine, 3 days), and completed secretory proteins of the vesicular cavity (leucine, 30 min). Within a narrow range of DOC concentrations (0.025–0.05%), the vesicular polypeptides were selectively released from the microsomes, while ribosomes, nascent polypeptides, and microsomal enzymes of the electron transport systems were unaffected. The detergent concentration which led to leakage of content was a function of the ionic strength and of the microsome concentration. At the lowest effective DOC concentration the microsomal membranes became reversibly permeable to macromoles as shown by changes in the density of the vesicles in Dextran gradients and by the extent of proteolysis by added proteases. Incubation of rough microsomes with proteases in the presence of 0.025% DOC also led to digestion of proteins from both faces of the microsomal membranes and to a lighter isopycnic density of the membrane vesicles.

The centriolar complex isolated from starfish spermatozoa

1981 ◽  
Vol 49 (1) ◽  
pp. 33-49 ◽  
Author(s):  
R. Kuriyama ◽  
H. Kanatani
Keyword(s):  
Gradient Centrifugation ◽  
Sucrose Density Gradient ◽  
Microtubule Assembly ◽  
High Concentration ◽  
Microtubule Organization ◽  
Sucrose Density Gradient Centrifugation ◽  
The Difference ◽  
Distal Centriole

Centrioles from spermatozoa of the starfish, Asterina pectinifera, were isolated and partially purified by solubilization of chromatin followed by sucrose density-gradient centrifugation. The ultrastructure of the isolated centriolar complex was investigated in whole mount preparations by electron microscopy. The complex unit was composed of a pair of centrioles and a pericentriolar structure, which associated with the distal end of the distal centriole by 9 spoke-like satellites extending radially to a marginal ring. Each satellite bifurcated at a dense node forming 2 fan-like shapes with a periodic striated pattern. The tubular structure of the centrioles easily disintegrated, leaving the pericentriolar structure or axonemal microtubules intact. The distal centriole in a spermatozoon served as an initiating site for flagellar microtubule assembly; that is, a number of “9 + 2′ axonemal tubules were observed adhering just beneath the distal end of the basal body. In experiments in vitro, polymerization of microtubule proteins purified from porcine brain was initiated by the structure at the ends of both proximal and distal centrioles, but not from the satellites or the marginal ring. Also, few if any microtubules were formed from the sides of each centriole, even in the presence of a high concentration of exogenous tubulin. On the other hand, centrioles of spermatozoa, when they were in mature ooplasm, could initiate the formation of sperm asters by microtubules. Therefore, centrioles in spermatozoa seem to be able to initiate microtubules in a 2 ways. A possible explanation of the difference between the 2 types of microtubule organization in vivo, i.e. in the sperm cell itself and in the ooplasm, it discussed.

scholarly journals Separation and Paired Proteome Profiling of Plant Chloroplast and Cytoplasmic Ribosomes

Plants ◽  
2020 ◽  
Vol 9 (7) ◽  
pp. 892
Author(s):  
Alexandre Augusto Pereira Firmino ◽  
Michal Gorka ◽  
Alexander Graf ◽  
Aleksandra Skirycz ◽  
Federico Martinez-Seidel ◽  
...  
Keyword(s):  
Ribosome Biogenesis ◽  
Gradient Centrifugation ◽  
Leaf Tissue ◽  
Proteome Analysis ◽  
Sucrose Density Gradient ◽  
Cross Linking ◽  
Sucrose Density Gradient Centrifugation ◽  
Cytoplasmic Ribosome ◽  
Plant Chloroplast

Conventional preparation methods of plant ribosomes fail to resolve non-translating chloroplast or cytoplasmic ribosome subunits from translating fractions. We established preparation of these ribosome complexes from Arabidopsis thaliana leaf, root, and seed tissues by optimized sucrose density gradient centrifugation of protease protected plant extracts. The method co-purified non-translating 30S and 40S ribosome subunits separated non-translating 50S from 60S subunits, and resolved assembled monosomes from low oligomeric polysomes. Combining ribosome fractionation with microfluidic rRNA analysis and proteomics, we characterized the rRNA and ribosomal protein (RP) composition. The identity of cytoplasmic and chloroplast ribosome complexes and the presence of ribosome biogenesis factors in the 60S-80S sedimentation interval were verified. In vivo cross-linking of leaf tissue stabilized ribosome biogenesis complexes, but induced polysome run-off. Omitting cross-linking, the established paired fractionation and proteome analysis monitored relative abundances of plant chloroplast and cytoplasmic ribosome fractions and enabled analysis of RP composition and ribosome associated proteins including transiently associated biogenesis factors.

scholarly journals Cellular gene transfer mediated by influenza virosomes with encapsulated plasmid DNA

2007 ◽  
Vol 405 (1) ◽  
pp. 41-49 ◽  
Author(s):  
Jørgen de Jonge ◽  
Johanna M. Leenhouts ◽  
Marijke Holtrop ◽  
Pieter Schoen ◽  
Peter Scherrer ◽  
...  
Keyword(s):  
Plasmid Dna ◽  
Gradient Centrifugation ◽  
Cationic Lipid ◽  
Sucrose Density Gradient ◽  
Target Cells ◽  
Sucrose Density Gradient Centrifugation ◽  
Viral Membrane ◽  
Viral Envelopes

Reconstituted influenza virosomes (virus membrane envelopes) have been used previously to deliver pDNA (plasmid DNA) bound to their external surface to a variety of target cells. Although high transfection efficiencies can be obtained with these complexes in vitro, the virosome-associated DNA is readily accessible to nucleases and could therefore be prone to rapid degradation under in vivo conditions. In the present study, we show a new method for the production of DNA–virosomes resulting in complete protection of the DNA from nucleases. This method relies on the use of the short-chain phospholipid DCPC (dicaproylphosphatidylcholine) for solubilization of the viral membrane. The solubilized viral membrane components are mixed with pDNA and cationic lipid. Reconstitution of the viral envelopes and simultaneous encapsulation of pDNA is achieved by removal of the DCPC from the mixture through dialysis. Analysis by linear sucrose density-gradient centrifugation revealed that protein, phospholipid and pDNA physically associated to particles, which appeared as vesicles with spike proteins inserted in their membranes when analysed by electron microscopy. The DNA–virosomes retained the membrane fusion properties of the native influenza virus. The virosome-associated pDNA was completely protected from degradation by nucleases, providing evidence for the DNA being highly condensed and encapsulated in the lumen of the virosomes. DNA–virosomes, containing reporter gene constructs, transfected a variety of cell lines, with efficiencies approaching 90%. Transfection was completely dependent on the fusogenic properties of the viral spike protein haemagglutinin. Thus, DNA–virosomes prepared by the new procedure are highly efficient vehicles for DNA delivery, offering the advantage of complete DNA protection, which is especially important for future in vivo applications.

scholarly journals Regulation of mammalian protein synthesis in vivo. Simulated transport of nuclear ribonucleoprotein complexes to the cytoplasm after cycloheximide treatment

1979 ◽  
Vol 178 (3) ◽  
pp. 643-649 ◽  
Author(s):  
J J Ch'ih ◽  
D M Duhl ◽  
L S Faulkner ◽  
T M Devlin
Keyword(s):  
Protein Synthesis ◽  
Gradient Centrifugation ◽  
Lethal Dose ◽  
Sucrose Density Gradient ◽  
Sucrose Density Gradient Centrifugation ◽  
Ribonucleoprotein Complexes ◽  
Treatment Analysis ◽  
Nuclear Ribonucleoprotein ◽  
Mammalian Protein

By studies in vivo with purified nuclei from rat liver, it was shown that a non-lethal dose of cycloheximide causes a decrease in the content of total nuclear ribonucleoprotein complexes by 2h after treatment. Analysis of the complex by sucrose-density-gradient centrifugation substantiated this observation for the faster-sedimenting complex, but showed an increase in the content of a smaller complex. Radioisotope incorporation studies showed that the overall decrease in nuclear ribonucleoprotein content was not due to a decreased synthesis, but rather to an increased transport to the cytoplasm. The results of a double-radioisotope technique support the conclusion that, during the inhibitory phase of protein synthesis brough on by cycloheximdie, gene transcription continues and the gene product is transported to the cytoplasm for subsequent translation.

5-ENE-3β-HYDROXYSTEROID DEHYDROGENASE OF HUMAN AND BOVINE ADRENOCORTICAL ENDOPLASMIC RETICULUM: SOLUBILIZATION AND FRACTIONATION

1977 ◽  
Vol 72 (2) ◽  
pp. 225-233 ◽  
Author(s):  
A. R. EASTMAN ◽  
A. M. NEVILLE
Keyword(s):  
Molecular Weight ◽  
Adrenal Glands ◽  
Gradient Centrifugation ◽  
Gel Filtration ◽  
Hydroxysteroid Dehydrogenase ◽  
Sucrose Density Gradient ◽  
Sucrose Density Gradient Centrifugation ◽  
Microsomal Membranes ◽  
Molecular Sizes ◽  
Triton X

SUMMARY Protein moieties of various molecular sizes and possessing 5-ene-3β-hydroxysteroid dehydrogenase activity have been successfully solubilized from the microsomal membranes of both bovine and human adrenal glands using a combination of Triton X-100 and sonication. These moieties have been studied by gel filtration, sucrose density gradient centrifugation and isoelectric focusing, and were shown to possess a minimum molecular weight of about 118000, with an isoelectric point between 7·2 and 7·4. The molecular weight was dependent upon the concentration of Triton X-100 used during fractionation. No separation of dehydrogenase activities toward the three steroid substrates, pregnenolone, 17α-hydroxypregnenolone and dehydroisoandrosterone, was observed. Changes in the relative activities for the steroid substrates during fractionation were observed, but have been attributed to the formation of allotypes rather than to the existence of separate dehydrogenases with restricted substrate specificity.

Detection of antibodies to rabies virus by immunoelectron microscopy

1978 ◽  
Vol 36 (2) ◽  
pp. 364-365
Author(s):  
R. K. Chaudhary ◽  
K. M. Charlton ◽  
M. T. Monette ◽  
A. E. Kelen
Keyword(s):  
Rabies Virus ◽  
Density Gradient Centrifugation ◽  
Gradient Centrifugation ◽  
Standard Technique ◽  
Sucrose Density Gradient ◽  
Sucrose Density Gradient Centrifugation ◽  
Live Virus ◽  
Human Diploid Cells ◽  
Diploid Cells

Immunization of humans and domesticated animals at risk of contracting rabies is common practice. The mouse neutralization test (MNT) is still the standard technique used for detecting and measuring antibody to rabies virus in sera of vacinees. However, it suffers from problems of reproducibility associated with tests performed in vivo. It also has the disadvantage of being expensive, time-consuming and hazardous. Hence, there has been a continuous search for a simple, rapid and safe test. In recent years, methods based on haemagglutination, haemadsorption, plaque reduction, immunofluorescence and radioimmunoassay have been developed, but none of them has eliminated the hazard involved in the use of live virus.With emphasis on laboratory safety, attempts were made to use inactivated rabies virus for antibody assay by immunoelectronmicroscopy (IEM), in comparison with the MNT.Inactivated rabies virus grown in human diploid cells was supplied by Connaught Laboratories Limited (CLL). The virus was purified by sucrose density gradient centrifugation and used at a concentration to give 35-50 particles per grid square.

Gastric and pancreatic intrinsic factor-mediated absorption of cobalamin in the dog

1989 ◽  
Vol 257 (3) ◽  
pp. G344-G349 ◽  
Author(s):  
R. M. Batt ◽  
N. U. Horadagoda
Keyword(s):  
Density Gradient Centrifugation ◽  
Gradient Centrifugation ◽  
Intrinsic Factor ◽  
Sucrose Density Gradient ◽  
Ileal Mucosa ◽  
Sucrose Density Gradient Centrifugation ◽  
Control Loops ◽  
Intrinsic Factors ◽  
Total Uptake

The effects of canine gastric and pancreatic intrinsic factors on uptake and subcellular localization of cobalamin have been investigated in vivo to determine whether these proteins could mediate the physiological absorption of cobalamin in the dog. Cyano [57Co]cobalamin was introduced into ileal loops in dogs under general anesthesia, either free (control) or bound to gastric or pancreatic intrinsic factor. At 2 h, total uptake of cobalamin by ileal mucosa was significantly enhanced after prior binding to either gastric or pancreatic intrinsic factor compared with controls. Displacement of receptor-bound cobalamin with EDTA showed that enhanced total uptake reflected increased internalization of cobalamin by both proteins. Findings after reorienting sucrose density gradient centrifugation of ileal mucosa from loops containing intrinsic factor-cobalamin complexes were consistent with a major lysosomal and perhaps endosomal localization of internalized cobalamin, in agreement with results after oral administration of cobalamin. In marked contrast, cobalamin was recovered predominantly in the soluble fractions and was not associated with particulate subcellular organelles in ileal mucosa from control loops. These findings suggest that both gastric and pancreatic intrinsic factors can promote the physiological absorption of cobalamin by receptor-mediated endocytosis in the dog.

scholarly journals Effects of oestradiol-17β and progesterone on total and nuclear-protein synthesis in epithelial and stromal tissues of the mouse uterus, and of progesterone on the ability of these tissues to bind oestradiol-17β

1970 ◽  
Vol 119 (4) ◽  
pp. 773-784 ◽  
Author(s):  
J. A. Smith ◽  
L. Martin ◽  
R. J. B. King ◽  
M. Vértes
Keyword(s):  
Protein Synthesis ◽  
Total Protein ◽  
Nuclear Protein ◽  
Gradient Centrifugation ◽  
Sucrose Density Gradient ◽  
Nuclear Proteins ◽  
Sucrose Density Gradient Centrifugation ◽  
Mouse Uterus

1. A method is described for separating uterine epithelium that is 80% pure and connective-tissue stroma that is 60% pure. This was used to study the effects of steroid hormones on total and nuclear-protein synthesis in these tissues. 2. Oestradiol-17β given alone produces mitoses in the epithelium but not in the stroma. It stimulated incorporation in vitro of [14C]lysine into total protein, histones and acidic nuclear proteins to a greater extent in epithelium than stroma. Incorporation into acidic nuclear proteins was most markedly stimulated, reaching four to six times the normal value 4h after treatment, and then declining rapidly. This peak was only seen in epithelial preparations. 3. After pretreatment with progesterone, oestradiol-17β has the reverse effect, producing mitoses only in stroma. Progesterone alone had no effect on the amounts or rates of incorporation of [14C]lysine into stromal nuclear proteins, but changes after oestradiol-17β treatment were similar to those seen in epithelium with oestradiol-17β alone. In the epithelium, progesterone alone depressed incorporation into histones and acidic nuclear proteins, but did not abolish the subsequent response to oestradiol-17β. With this treatment there was a rapid, large and transient increase in incorporation into epithelial total protein not seen with oestradiol-17β alone. 4. Progesterone had no qualitative effect on the distribution of specific oestrogen-binding proteins, as judged by sucrose-density-gradient centrifugation. However, progesterone treatment increased the uptake in vivo of [6,7-3H]oestradiol-17β by stroma, and it is possible that this is important although the differences were not apparent after labelling in vitro.

scholarly journals Heterogeneity of smooth endoplasmic reticulum from rat liver studied by two-phase partitioning

1989 ◽  
Vol 262 (1) ◽  
pp. 55-61 ◽  
Author(s):  
P Gierow ◽  
B Jergil
Keyword(s):  
Rat Liver ◽  
Smooth Endoplasmic Reticulum ◽  
Gradient Centrifugation ◽  
Sucrose Density Gradient ◽  
Phase System ◽  
Marker Enzymes ◽  
Two Phase ◽  
Sucrose Density Gradient Centrifugation ◽  
Phase Partitioning ◽  
Microsomal Membranes

Smooth microsomal membranes, prepared from rat liver by sucrose-density-gradient centrifugation, were subfractionated by counter-current distribution in an aqueous two-phase system consisting of poly(ethylene glycol) and Dextran T500. A comparison of the distribution curves of marker enzymes, together with theoretically calculated curves, indicated the presence of at least five membrane subfractions, differing in the ratios of the marker enzymes. Glucose-6-phosphatase and arylesterase distributed in one manner, and NADPH-cytochrome c reductase and NADH-ferricyanide reductase in another. Evidence for further heterogeneities in the distribution of marker enzymes in smooth microsomes was obtained by analysing the membrane domain structure using a recently described method [Albertsson (1988) Q. Rev. Biophys. 21, 61-98]. Phenobarbital treatment did not influence the behaviour of the marker enzymes.

scholarly journals Fractionation of microsomal membranes on the basis of their surface properties

1978 ◽  
Vol 172 (1) ◽  
pp. 189-192 ◽  
Author(s):  
R Ohlsson ◽  
B Jergil ◽  
H Walter
Keyword(s):  
New York ◽  
Surface Properties ◽  
Gradient Centrifugation ◽  
Membrane Surface ◽  
Sucrose Density Gradient ◽  
Sucrose Density Gradient Centrifugation ◽  
Membrane Surfaces ◽  
Microsomal Membranes ◽  
Poly Ethylene ◽  
Rat Liver Microsome

Partition in dextran-poly(ethylene glycol) aqueous-phase systems can be used for both membrane subfractionation and gaining information on membrane surface properties [H. Walter (1977) in Methods of Cell Separation (Catsimpoolas, N., ed.), vol. 1, pp. 307-354, Plenum, New York]. Smooth, light rough and heavy rough rat liver microsome (obtained by sucrose-density-gradient centrifugation) were subjected to countercurrent distribution in such a system. Smooth microsomal membranes had the highest, heavy rough microsomal membranes the lowest and light rough microsomal membranes an intermediate partition coefficient. The separation is based primarily on hydrophobic differences in the membrane surfaces of the three preparations and is thus due to microsomal properties not previously utilized in their fractionation. The method permits additional subfractionations of microsomes.

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