Chromosome age and segregation during sporulation of Bacillus megaterium

1978 ◽  
Vol 24 (10) ◽  
pp. 1227-1235 ◽  
Author(s):  
Anthony D. Hitchins
Keyword(s):  
Bacillus Megaterium ◽  
Density Gradient Centrifugation ◽  
Gradient Centrifugation ◽  
Buoyant Density ◽  
Growth Period ◽  
Circular Dna ◽  
Chromosomal Segregation ◽  
Seven Generations ◽  
Minor Correction

The effect of chromosome age on segregation during sporulation was investigated. Vegetative cells of Bacillus megaterium were labeled with [Me-3H]thymine and then were grown at 30 °C in nonradioactive medium for various times before being allowed to sporulate. The ratio of the amount of label in sporal DNA to that in sporangial DNA, obtained after minor correction for the sporulation frequency, remained essentially constant as the postlabeling growth period was increased from one to seven generations. The spores were preferentially located at the older poles of sporangia, i.e. the poles formed by divisions occurring prior to those forming the sporangia. Therefore, it seems that old (labeled) chromosomes segregate randomly with respect to both the morphological and genealogical polarities of sporangia. Examination of total cell lysates by dye–buoyant density gradient centrifugation revealed the presence of covalently closed circular DNA from cells grown at 37 °C, but none was obtained from cells grown at 30 °C. Thus, possible interference by large amounts of extrachromosomal DNA in the determination of the chromosomal segregation pattern is unlikely.

Plasmid detection in a bacteriocinogenic strain of Clostridium perfringens

1980 ◽  
Vol 26 (8) ◽  
pp. 1018-1022 ◽  
Author(s):  
A. W. Li ◽  
P. J. Krell ◽  
D. E. Mahony
Keyword(s):  
Clostridium Perfringens ◽  
Plasmid Dna ◽  
Gel Electrophoresis ◽  
Density Gradient Centrifugation ◽  
Gradient Centrifugation ◽  
Buoyant Density ◽  
Size Distributions ◽  
Agarose Gel Electrophoresis ◽  
Circular Dna ◽  
Molecular Weights

Bacteriocinogenic Clostridium perfringens, strain 28, harboured plasmid DNA detectable by dye-buoyant density-gradient centrifugation. This plasmid DNA was absent from an ultraviolet light cured variant which had simultaneously lost its immunity and ability to produce bacteriocin. Agarose gel electrophoresis of the plasmid DNA revealed at least six bands but denaturation experiments suggested three plasmids occurring in more than one conformation. Electron microscopy revealed three major size distributions of circular DNA of molecular weights 1,5.6, and 7.1 megadaltons. Some evidence suggests that the 5.6 megadalton plasmid may control bacteriocin 28 production.

scholarly journals Covalently closed, circular DNA in kappa endosymbionts ofParamecium

1976 ◽  
Vol 27 (2) ◽  
pp. 161-170 ◽  
Author(s):  
Judith A. Dilts
Keyword(s):  
Density Gradient Centrifugation ◽  
Gradient Centrifugation ◽  
Buoyant Density ◽  
Bacterial Chromosome ◽  
Contour Length ◽  
Paramecium Tetraurelia ◽  
Extrachromosomal Dna ◽  
Circular Dna ◽  
Covalently Closed Circular Dna ◽  
Circular Molecule

SUMMARYCaedobacter taeniospiralis(kappa), a bacterial endosymbiont isolated fromParamecium tetraureliastock 51, contains, in addition to the bacterial chromosome, covalently closed circular DNA molecules as shown by isolation on dye-buoyant-density gradients. The closed circular molecule has a contour length of 13·75 ± 0·04 µm with a buoyant density of 1·698 g/cm3. The buoyant density of the bacterial chromosome is 1·700–1·701 g/cm3. Kappa of the 51 group isolated from stock 298 and stock 6g2,P. tetraurelia, also contain the closed circular DNA. Two forms of kappa coexist in paramecia: brights and nonbrights. Examination by density-gradient centrifugation of the DNA of brights and nonbrights shows the extrachromosomal DNA to be associated mainly with brights. It is suggested that the extrachromosomal DNA might be the determinant for the refractile bodies and the helical phage-like structures found in brights.

scholarly journals Evidence that platelet density depends on the alpha-granule content in platelets

Blood ◽  
1984 ◽  
Vol 63 (2) ◽  
pp. 482-485 ◽  
Author(s):  
BA van Oost ◽  
AP Timmermans ◽  
JJ Sixma
Keyword(s):  
Density Distribution ◽  
Density Gradient ◽  
Density Gradient Centrifugation ◽  
Platelet Rich Plasma ◽  
Gradient Centrifugation ◽  
Buoyant Density ◽  
Adenosine Diphosphate ◽  
Density Gradients

Abstract The relation between platelet buoyant density and beta-thromboglobulin (beta-TG), a marker for platelet alpha-granule content, was assessed by three independent approaches. (1) Platelets were separated on iso- osmolar discontinuous Stractan density gradients into five fractions, ranging in density from 1.061 g/ml to 1.091 g/ml (20 degrees C). The beta-TG content (mean +/- SD, n = 17) increased with the platelet density from 27.8 +/- 8.6 micrograms beta-TG/10(9) cells (20% less- dense platelets) up to 65.6 +/- 15.5 micrograms beta-TG/10(9) cells (15% most-dense platelets). (2) Activation of platelets in platelet- rich plasma with thrombin, adenosine diphosphate, collagen, or epinephrine resulted in a decreased density of the platelets. This was only seen when there was simultaneous secretion of beta-TG. (3) The less-dense and the more-dense platelet fractions, after isolation by density gradient centrifugation, were separately treated with thrombin. After complete degranulation, the density distribution of the originally less-dense and more-dense platelets were identical and were much narrower than the density distribution of resting platelets.

scholarly journals Mucins secreted by a transformed cell line derived from human tracheal gland cells1

1997 ◽  
Vol 326 (2) ◽  
pp. 431-437 ◽  
Author(s):  
Jean-Marc LO-GUIDICE ◽  
Marc D. MERTEN ◽  
Geneviève LAMBLIN ◽  
Nicole PORCHET ◽  
Marie-Christine HOUVENAGHEL ◽  
...  
Keyword(s):  
Molecular Mass ◽  
Cell Line ◽  
Density Gradient ◽  
Density Gradient Centrifugation ◽  
Gradient Centrifugation ◽  
Buoyant Density ◽  
Simian Virus 40 ◽  
Simian Virus ◽  
High Molecular Mass ◽  
Cscl Density Gradient

High-molecular-mass glycoconjugates are secreted by the continuous cell line MM-39, which has been obtained from cultured human tracheal gland cells transformed by simian virus 40. They were purified on Sepharose® CL-4B and then by two steps of density-gradient centrifugation. High-molecular-mass glycoproteins resistant to digestion by hyaluronidase, chondroitin ABC lyase and heparitinase were obtained, in addition to hyaluronic acid and proteoglycans. They were susceptible to β-elimination. They contained polylactosaminoglycan chains as well as carbohydrate chains with a terminal sialic acid in the NeuAc α2-3 sequence. Most of them have a buoyant density of 1.45 g/ml in CsCl-density-gradient centrifugation, except for MUC1. The MM-39 cells were also characterized by a high expression of MUC1 and MUC4 genes, but they did not express MUC2, MUC3, MUC5B and MUC5AC. Therefore the MM-39 cells synthesized mucin-like glycoproteins as well as lysozyme and mucous proteinase inhibitor [Merten, Kammouni, Renaud, Birg, Mattéi and Figarella (1996) Am. J. Respir. Cell. Mol. Biol. 15, 520–528]; they should be considered as having a mixed, both serous and mucous, phenotype.

Transgressive, reiterative selection by continuous buoyant density gradient centrifugation of Dunaliella salina results in enhanced lipid and starch content

2015 ◽  
Vol 9 ◽  
pp. 194-203 ◽  
Author(s):  
Leyla T. Hathwaik ◽  
Doug Redelman ◽  
Vera Samburova ◽  
Barbara Zielinska ◽  
David K. Shintani ◽  
...  
Keyword(s):  
Density Gradient ◽  
Dunaliella Salina ◽  
Density Gradient Centrifugation ◽  
Starch Content ◽  
Gradient Centrifugation ◽  
Buoyant Density

scholarly journals The effect of thrombin on the density distribution of blood platelets: detection of activated platelets in the circulation

Blood ◽  
1983 ◽  
Vol 62 (2) ◽  
pp. 433-438
Author(s):  
B van Oost ◽  
IH van Hien-Hagg ◽  
AP Timmermans ◽  
JJ Sixma
Keyword(s):  
Cardiopulmonary Bypass ◽  
Density Distribution ◽  
Density Gradient Centrifugation ◽  
Blood Platelets ◽  
Gradient Centrifugation ◽  
Buoyant Density ◽  
Human Platelets ◽  
Activated Platelets

The buoyant density of human platelets is decreased after they have been aggregated and induced to secrete their granule content by thrombin. This change in density was detected by discontinuous density gradient centrifugation using arabinogalactan (Stractan) solutions. The density decrease was dependent on the thrombin concentration and paralleled the extent of serotonin and beta-thromboglobulin secretion. The degranulated platelets maintained their integrity, and many of their functional properties. Mixtures of degranulated platelets and normal platelets could be resolved by Stractan gradient centrifugation and the number of degranulated platelets quantitated. Using this method, increased levels of less dense platelets were shown to occur after cardiopulmonary bypass. Assay of changes in platelet density by Stractan gradient centrifugation is a useful method for detection of activated platelets in vitro and in vivo.

Determination of the Density Distribution of Human Platelets - Methodological Aspects and Comparison with Other Tests for Platelet Activation

1982 ◽  
Vol 47 (03) ◽  
pp. 239-243 ◽  
Author(s):  
B A van Oost ◽  
I H van Hien-Hagg ◽  
B F E Veldhuyzen ◽  
A P M Timmermans ◽  
J J Sixma
Keyword(s):  
Platelet Activation ◽  
Gradient Centrifugation ◽  
Buoyant Density ◽  
Human Platelets ◽  
Thrombotic Disease ◽  
Platelet Aggregate ◽  
Thrombotic Complications ◽  
Methodological Aspects ◽  
Function Testing

SummaryStimulation of human platelets to release results in decreased buoyant density. This decreased density provides a tool to detect circulating platelets which have participated in a thrombotic process. Platelet density gradient centrifugation using Stractan was standardized and the effects of anticoagulation, temperature, and osmolarity were investigated. In 7 out of 32 patients with thrombotic disease less dense platelets were found. Platelet activation in the patient group was also indicated by spontaneous aggregation (10/32), decreased circulating platelet aggregate ratios (5/24) and elevated plasma β-thromboglobulin levels (2/11). Several of these tests were also abnormal in diabetes mellitus thrombocytosis, leukaemia and several systemic diseases with thrombotic complications. The platelet density test using Stractan is reproducible and independent of other tests for platelet activation and is therefore potentially a useful extension of platelet function testing in patients with thrombotic disease.

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