[55] Isodensity equilibrium centrifugation of ribosomal particles; the calculation of the protein content of ribosomes and other ribonucleo-proteins from buoyant density measurements

1971 ◽  
pp. 512-521 ◽  
Author(s):  
Mary G. Hamilton
Keyword(s):  
Protein Content ◽  
Buoyant Density ◽  
Density Measurements ◽  
Equilibrium Centrifugation

Disappearance of the covalently closed circular cryptic plasmid PO-2 in Salmonella pullorum MS35 containing F77

1974 ◽  
Vol 20 (4) ◽  
pp. 551-557
Author(s):  
Paul W. Stiffler ◽  
D. E. Schoenhard
Keyword(s):  
Salmonella Typhimurium ◽  
Sucrose Gradient ◽  
Buoyant Density ◽  
Sedimentation Coefficient ◽  
Apparent Effect ◽  
Donor Property ◽  
Circular Dna ◽  
Salmonella Pullorum ◽  
Cryptic Plasmids ◽  
Equilibrium Centrifugation

The physical basis of the donor property of Salmonella pullorum donor strains MS8300, MS830, and MS831 carrying the F77 factor from Salmonella typhimurium was investigated by dye-buoyant density equilibrium centrifugation and zonal centrifugation in neutral sucrose gradients. Centrifugation of the MS8300 and MS831 closed circular DNA material in a 20 to 31% neutral sucrose gradient resulted in a profile having one sharp peak of radioactivity with a sedimentation coefficient of 17 S and a broad peak extending from 65 to 70 S. The 17- and 65-S species were isolated from the isogenic F− strain MS83. These appeared identical with those isolated previously in S. pullorum MS53 as the cryptic plasmids PO-1 and PO-2 respectively. Cosedimentation of differentially labeled F77 DNA and the lysate containing the 65-S and 70-S species suggested that the 70-S species is the autonomous F77 factor in strains MS8300 and MS831. Lysates of MS830 similarly treated produced a profile containing the 17-S molecule and possibly some 70-S molecules but no 65-S molecules. It was concluded that the F77 factor was integrated in most cells and that the covalently closed circular state of PO-2 plasmid was lost. The mutation in the cysE gene of the F77 factor carried by MS831 had no apparent effect on the covalently closed circular nature of PO-2 plasmid, although F77 no longer seemed to mobilize the chromosome from the cysE locus.

Inferred protein content and distribution from density measurements of calcitic and aragonitic otoconia

1993 ◽  
Vol 66 (2) ◽  
pp. 225-232 ◽  
Author(s):  
Kenneth G. Pote ◽  
Christian H. Weber ◽  
Robert H. Kretsinger
Keyword(s):  
Protein Content ◽  
Density Measurements

The Density Distribution Of Intact Platelets Following Their Isolation From All Other Blood Constituents

1981 ◽  
Author(s):  
T Shaw ◽  
J F Martin ◽  
C N Chesterman ◽  
D G Peninqton
Keyword(s):  
Buoyant Density ◽  
Lactic Dehydrogenase ◽  
Blood Platelet ◽  
Dense Granule ◽  
Velocity Sedimentation ◽  
Full Density ◽  
Blood Constituents ◽  
Second Gradient ◽  
Induced Aggregation ◽  
Equilibrium Centrifugation

A method for measuring the buoyant density of platelets which function normally after the procedure, has been developed and critically compared to published methods.Following velocity sedimentation into a gradient of polyvinyl pyrrol 1idone-coated colloidal silica particles (Percoll) at physiological pH and osmolarity, 90% (n=10, SD=10) of the whole blood platelet population was recovered with leukocyte contamination of .002% (n=10, SD=.001); erythrocyte contamination was less.After centrifugation to equilibrium through a second continuous linear Percoll gradient, platelet density showed a Gaussian distribution about a mode of 1.0645 g/ml. (n=13, SD=.0015). Leakage of β thromboglobulin (βTG), lactic dehydrogenase (LDH) and serotonin into the gradients was negligible. Intracellular LDH, serotonin and total protein correlated closely with platelet count, but βTG distribution was skewed towards the denser fractionsPlatelets recovered from the second gradient showed normal aggregation patterns and produced thromboxane B2 and secreted βTG when stimulated by thrombin or arachidonic acid. Addition of plasma was necessary to produce ristocetin-and ADP-induced aggregation, and significant radioactivity was not associated with platelets isolated from blood to which 125I had been addedUnder physiological conditions, arabinogalactan II (Stractan) caused more spontaneous leakage of α-and dense- granule markers than did Percoll. Platelets taken from different interfaces of a discontinuous Stractan gradient were seen to contain platelets of the full density range when they underwent equilibrium centrifugation in linear continuous Stractan or Percoll gradients.True buoyant density of minimally altered platelets has been measured by this new technique.

scholarly journals The number of sex-factors per chromosome in Escherichia coli

1971 ◽  
Vol 121 (1) ◽  
pp. 93-103 ◽  
Author(s):  
R. Frame ◽  
J. O. Bishop
Keyword(s):  
Escherichia Coli ◽  
Buoyant Density ◽  
E Coli ◽  
Caesium Chloride ◽  
Genetic Complexity ◽  
Total Dna ◽  
Gal Genes ◽  
Episomal Dna ◽  
Equilibrium Centrifugation

A substituted sex-factor of Escherichia coli, F′8 gal, was transferred to Proteus mirabilis by conjugation. The DNA of the episome was partially purified from Proteus DNA by preparative equilibrium centrifugation in caesium chloride, and by a bulk method using hydroxyapatite. The buoyant density of the episomal DNA is 1.707, corresponding to a (G+C) content of 47%. By optical renaturation the genetic complexity of the episomal DNA was found to be 76×106 daltons. RNA was synthesized in vitro by using the episomal DNA as template. By hybridizing this RNA with DNA extracted from E. coli carrying F′8 gal, it is shown that the number of copies of the episome per replicating chromosome is close to two during exponential growth. The episome makes up about 4.4% of the total DNA of the growing cells. The activities of galactokinase and galactose 1-phosphate uridylyl-transferase in cells with and without episomal and chromosomal gal genes were found to be proportional to the number of gal genes present, when the cells were induced with d-fucose, but not when they were induced with d-galactose.

Properties of a D-quinovosamine-producing Achromobacter

1968 ◽  
Vol 14 (2) ◽  
pp. 165-171 ◽  
Author(s):  
R. R. Colwell ◽  
E. J. Smith ◽  
G. B. Chapman
Keyword(s):  
Deoxyribonucleic Acid ◽  
Buoyant Density ◽  
Cesium Chloride ◽  
Wall Structure ◽  
Gram Negative Bacteria ◽  
Negative Bacterium ◽  
Acid Base ◽  
Gram Negative ◽  
Density Measurements ◽  
Ultrathin Sections

The bacterial mucopolysaccharide of a Gram-negative bacterium, Georgetown strain COC-21, includes a hexosamine component, D-quinovosamine. The bacterium has been identified and classified as Achromobacter georgiopolitanum n. sp. and a description of the organism is given. The overall deoxyribonucleic acid base composition, determined by buoyant density measurements in cesium chloride, is 41 moles %. Electron micrographs of ultrathin sections reveal a double-layered cell wall structure typical of the Gram-negative bacteria.

UV-Empfindlichkeit von λ-Phagen mit variablem Bromuracil-Gehalt / UV-Sensitivity of λ-Phages with Various BU-Contents

1974 ◽  
Vol 29 (5-6) ◽  
pp. 289-293 ◽  
Author(s):  
Friedrich Mönkehaus
Keyword(s):  
Short Wavelength ◽  
Buoyant Density ◽  
Dna Bases ◽  
Density Measurements ◽  
Long Wavelength ◽  
E Coli ◽  
Uv Sensitivity ◽  
Sensitivity Loss ◽  
Cscl Density Gradient ◽  
Dna Strands

Heat induction of E. coli CR 34 (λcI857)/λ growing in media with variing bromouracil (BU)-contents yielded A-phages with different amounts of BU in their DNA-strands. The percentage substitution of thymine was determined by buoyant density measurements in a CsCl-density gradient. After irradiation of the phages with long wavelength UV (302/313 nm) and short wavelength UV (254 nm) the sensitivity (loss of infectivity) was determined as a function of the degree of BU-substitution. It was found that after irradiation with long wavelength UV the cross section is proportional to the percentage BU-substitution, whereas after irradiation with short wavelength UV it is not. The results can be explained by assuming energy transfer from the four DNA-bases to the BU.

DNA BASE COMPOSITION OF CYTOPHAGA MARINOFLAVA N. SP. DETERMINED BY BUOYANT DENSITY MEASUREMENTS IN CESIUM CHLORIDE

1966 ◽  
Vol 12 (6) ◽  
pp. 1099-1103 ◽  
Author(s):  
R. R. Colwell ◽  
R. V. Citarella ◽  
P. K. Chen
Keyword(s):  
Nucleic Acid ◽  
Base Composition ◽  
Marine Bacterium ◽  
Deoxyribonucleic Acid ◽  
Buoyant Density ◽  
Cesium Chloride ◽  
Dna Base Composition ◽  
Density Measurements ◽  
Dna Base ◽  
Relationship Of

A marine bacterium, NCMB 397, host strain for bacteriophages NCMB 384 and 385, has been subjected to taxonoinic analysis. Overall base composition of the highly purified deoxyribonucleic acid was determined and found to be 37 moles % guanine + cytosine. The phenetic and nucleic acid data suggest significant relationship of this strain and members of the genus Cytophaga. A description of Cytophaga marinoflava n. sp. is presented.

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