scholarly journals SYNTHESIS OF CHLOROPLAST DNA IN ISOLATED CHLOROPLASTS

1968 ◽  
Vol 38 (1) ◽  
pp. 151-157 ◽  
Author(s):  
N. Steele Scott ◽  
Vinod C. Shah ◽  
Robert M. Smillie
Keyword(s):  
Molecular Weight ◽  
Chloroplast Dna ◽  
Euglena Gracilis ◽  
Bacterial Contamination ◽  
Actinomycin D ◽  
Density Gradient Centrifugation ◽  
Tritiated Thymidine ◽  
Gradient Centrifugation ◽  
Acid Stable ◽  
Isolated Chloroplasts

Chloroplasts isolated from Euglena gracilis incorporated both tritiated thymidine 5'-triphosphate and tritiated deoxyadenosine 5'-triphosphate into an acid-stable fraction. The incorporation was dependent on the presence of all four deoxynucleoside triphosphates and was sensitive to treatment with deoxyribonuclease and actinomycin D. It was demonstrated that bacterial contamination could not account for the incorporation of label. Extraction of DNA from the chloroplasts and subsequent density gradient centrifugation of the DNA in CsCl2 showed that the incorporation was into chloroplast DNA (ρ = 1.686) of high molecular weight.

scholarly journals A study of nucleated erythrocytes by density-gradient centrifugation in a zonal rotor

1969 ◽  
Vol 111 (4) ◽  
pp. 583-591 ◽  
Author(s):  
A P Mathias ◽  
D. Ridge ◽  
N. St G. Trezona
Keyword(s):  
Molecular Weight ◽  
Ribosomal Rna ◽  
Base Composition ◽  
Density Gradient Centrifugation ◽  
Gradient Centrifugation ◽  
Density Gradients ◽  
Avian Erythrocytes ◽  
Nuclear Rna ◽  
Zonal Rotor

1. Several substances of high molecular weight were examined for their suitability as suspension media in the formation of density gradients for the zonal centrifugation of avian erythrocytes. None proved satisfactory. 2. The behaviour of pigeon erythrocytes in rate-sedimentation experiments in a type A zonal rotor with density gradients of sucrose was examined. The mature cells sediment more rapidly than the younger cells and have a lower RNA/DNA ratio. Maturation is accompanied by a greater loss of RNA from the nucleus than from the cytoplasm. 3. The base composition of the nuclear RNA and of the two species of cytoplasmic ribosomal RNA is reported. 4. The RNA of erythrocytes may be labelled in vivo by injection of inorganic [32P]phosphate. The cells most active in the synthesis of RNA sediment less rapidly than the bulk of the cells. 5. Reticulocyte nuclei sediment more slowly than those from erythrocytes. Reticulocyte nuclei have a mean volume of 35μ3 and are isopycnic with sucrose of density 1·2871 (measured at 20°). Maturation of the nuclei causes them to shrink to a volume of 25μ3 and the density to increase to 1·2944.

scholarly journals Appearance of a methylated ribonucleic acid on illumination of Euglena gracillis cells grown in the dark

1971 ◽  
Vol 125 (2) ◽  
pp. 401-405 ◽  
Author(s):  
M. Perl
Keyword(s):  
Molecular Weight ◽  
Nucleic Acid ◽  
High Molecular Weight ◽  
Ribonucleic Acid ◽  
Density Gradient Centrifugation ◽  
Gradient Centrifugation ◽  
Sucrose Density Gradient ◽  
Acid Fraction ◽  
Sucrose Density Gradient Centrifugation ◽  
Exclusion Chromatography

Investigation of the methylation of nucleic acids by [Me-3H]methionine after illumination of Euglena cells grown in the dark has shown that a high-molecular-weight nucleic acid fraction undergoes methylation after exposure to light for 60–120min. This methylated nucleic acid fraction was isolated both by sucrose-density-gradient centrifugation and exclusion chromatography on Sephadex G-200. The fraction was shown to consist of a preformed RNA that is present in cells grown in the dark and which on illumination is transmethylated by methionine.

Mise en évidence d'ADN extrachromosomique chez Rhizobium meliloti

1978 ◽  
Vol 24 (8) ◽  
pp. 960-966 ◽  
Author(s):  
M. Bechet ◽  
J. B. Guillaume
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Base Composition ◽  
Density Gradient Centrifugation ◽  
Rhizobium Meliloti ◽  
Gradient Centrifugation ◽  
Buoyant Density ◽  
Sedimentation Analysis ◽  
Extrachromosomal Dna ◽  
Very High

Seven effective (nitrogen-fixing) strains of Rhizobium meliloti have been studied. By sedimentation analysis of their alkaline lysates in alkaline sucrose gradients, a plasmid was found in four strains. In a strain (2011 str 3) which gave no result with this method, supercoiled DNA was detected by CsCl-dye buoyant density gradient centrifugation. That result was confirmed by analytical Cs2SO4–Ag+ density gradients, which showed a heterogeneity in the average base composition of the DNA extracted from three strains, including the 2011 str 3 strain. Two of those last strains seemed to contain an extrachromosomal DNA of very high molecular weight.

Interaction of DNA with ribosomes in cell-free protein synthetizing systems of Chlorella pyrenoidosa

1969 ◽  
Vol 24 (3) ◽  
pp. 321-327 ◽  
Author(s):  
G. Galling
Keyword(s):  
Actinomycin D ◽  
Density Gradient Centrifugation ◽  
Gradient Centrifugation ◽  
Chlorella Pyrenoidosa ◽  
Sucrose Density Gradient ◽  
Amino Acid Incorporation ◽  
Sucrose Density Gradient Centrifugation ◽  
Free Protein ◽  
Green Alga Chlorella ◽  
Kinetics Of

1. In cell-free protein synthetizing systems of the green alga Chlorella pyrenoidosa, DNA from various sources enhances the amino acid incorporation.2. This stimulation is neither inhibited by actinomycin D nor by chloramphenicol or cycloheximide (actidione).3. In the presence of ribonuclease, some precipitable polypeptide is formed with DNA, although the endogenous incorporation is completely inhibited by ribonuclease.4. After sucrose density gradient centrifugation, polysomal aggregates of ribosomes with DNA are found. Electron micrographs of such polysomes show a direct association of the DNA molecule with several ribosomes.5. In Chlorella, direct translation of DNA can be obtained also in the presence of neomycin. The kinetics of this reaction are different from those of endogenous m-RNA mediated and of DNA stimulated polypeptide synthesis.

scholarly journals THE SUBUNITS IN RABBIT ANTI-FORSSMAN IGM ANTIBODY

1968 ◽  
Vol 127 (5) ◽  
pp. 967-982 ◽  
Author(s):  
Michael M. Frank ◽  
John H. Humphrey
Keyword(s):  
Molecular Weight ◽  
Binding Sites ◽  
Density Gradient Centrifugation ◽  
Gradient Centrifugation ◽  
Sheep Erythrocyte ◽  
Gel Filtration ◽  
Isolation Procedure ◽  
Multiple Binding Sites ◽  
Multiple Binding ◽  
Forssman Antibody

Rabbit IgM anti-Forssman antibody was highly purified and the subunits obtained on reduction and alkylation were labeled radioactively and isolated by two different and unrelated methods. In both cases the subunits were found to have a molecular weight of about 90,000, based on their behavior on density gradient centrifugation and gel filtration, and evidence is given that they contained one light and one heavy chain. The subunits bound only weakly to sheep erythrocyte stroma, and only half could be shown to possess antigen specific sites. The data are consistent with the concept that each anti-Forssman IgM molecule has five effective binding sites, but it is uncertain whether the ineffectiveness of the remaining five H-L chain pairs is inherent in the structure of the IgM molecule or an artifact due to the isolation procedure. Intact IgM anti-Forssman antibody binds very firmly to structures containing multiple repeating antigen sites, and it appears that this is due to the presence of multiple binding sites on the molecule.

Nucleinsäuren in Chloroplasten I. Charakterisierung der DNS und RNS von Antirrhinum majus

1967 ◽  
Vol 22 (10) ◽  
pp. 1068-1076 ◽  
Author(s):  
Hans Georg Ruppel
Keyword(s):  
Nucleic Acids ◽  
Chloroplast Dna ◽  
Density Gradient ◽  
Density Gradient Centrifugation ◽  
Gradient Centrifugation ◽  
Size Fraction ◽  
Sedimentation Coefficient ◽  
Antirrhinum Majus ◽  
Freeze Dried ◽  
Fraction I

The occurrence of nucleic acids in chloroplast preparations and leaves of Antirrhinum majus has been investigated.Chloroplast preparations isolated from freeze-dried leaves in a non-aqueous medium were found to contain DNA. Characterization of the DNA was based on chemical analyses and density gradient centrifugation. The chloroplast DNA has a density of 1.698 g/cm3 corresponding to a guaninecytosine content of 37 — 38%. The hyperchromic effect of the DNA has shown its double-stranded structure. Leaf DNA has also been characterized by density gradient centrifugation and shown to contain as major component the nuclear DNA with a density of 1.689 g/cm3 which corresponds to a guanine-cytosine content of about 31% and a minor component identified as chloroplast DNA.Extraction of the total nucleic acids of chloroplast preparations and their chromatographic separation on methylated serum albumin column yielded 5 fractions as follows: Soluble RNA (fraction I) with s=3.8—4.0, DNA (fraction II) containing small but detectable amounts of an unknown RNA component, two RNA fractions presumable of ribosomal origin with s = 17 (fraction III) and s = 26 (fraction IV), and a RNA fraction heterogeneous in molecular size (fraction V) with s=23 — 50. The soluble RNA has a high GC-content whereas fraction V shows a relative high adenine content. Compared with the nucleic acids from leaves the chloroplast preparations contain the same fractions, differing only in the higher content of fraction III related to the amount of fraction IV. Beside the DNA fraction of leaf extract with the sedimentation coefficient of s = 12 — 13 a further UV-absorbing component with s=5.0—5.5 has been found. Its character is unknown.

Purification et quelques propriétés de l'AMPc phosphodiestérase d'Arthrobacter crystallopoietes

1988 ◽  
Vol 66 (5) ◽  
pp. 454-459 ◽  
Author(s):  
François Schneider ◽  
Gérard Lefebvre ◽  
Michèle Ribolzi-Chery ◽  
Jean-Michel Bertin ◽  
Robert Gay
Keyword(s):  
Molecular Weight ◽  
Active Site ◽  
Cyclic Nucleotides ◽  
Density Gradient Centrifugation ◽  
Gradient Centrifugation ◽  
Gel Filtration ◽  
Negative Cooperativity ◽  
Divalent Ions ◽  
Camp Phosphodiesterase ◽  
Hydrolysis Of

cAMP phosphodiesterase was purified 8250-fold from extracts of Arthrobacter crystallopoietes, primarily by hydrophobic chromatography. The molecular weight of this enzyme was estimated as 51 000 by gel filtration and density-gradient centrifugation. The results suggest that the enzyme consists of two subunits with a molecular weight of 25 600. Properties of this enzyme are reported, including its negative cooperativity. This phosphodiesterase specifically catalyzes the hydrolysis of 3′,5′-cyclic nucleotides. Divalent ions either have no effect on activity or are weak inhibitors. Photooxidation of the enzyme with methylene blue and treatment with mercuribenzoates suggest that this enzyme may possess an imidazole group within its active site. The effects of thiols and Fe2+ on activity suggests that this enzyme may be a metalloenzyme.

A malate dehydrogenase of high molecular weight, from bean leaves

1968 ◽  
Vol 46 (5) ◽  
pp. 719-720 ◽  
Author(s):  
William Habig ◽  
David Racusen
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Malate Dehydrogenase ◽  
Density Gradient Centrifugation ◽  
Gradient Centrifugation ◽  
Sucrose Density Gradient ◽  
Sucrose Density Gradient Centrifugation ◽  
Molecular Weights ◽  
Young Leaves ◽  
Bean Leaves

Two forms of malate dehydrogenase (MDH) of widely differing molecular weight were found in primary leaves of Phaseolus vulgaris. Their molecular weights were estimated as 69 000 and 275 000 by sucrose density gradient centrifugation. The ratio of these two forms followed an orderly course in which the high molecular weight MDH increased from near zero in very young leaves to about 35% of the total MDH activity in leaves older than 2 weeks. Conditions which cause the high molecular weight MDH to dissociate to active normal molecular weight enzyme are discussed.

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