scholarly journals Characterization of cytoplasmic and nuclear genomes in the colorless alga Polytoma. II. General characterization of organelle nucleic acids.

1976 ◽  
Vol 69 (2) ◽  
pp. 371-382 ◽  
Author(s):  
C Siu ◽  
H Swift ◽  
K Chiang
Keyword(s):  
Nucleic Acids ◽  
Chlamydomonas Reinhardtii ◽  
Ribosomal Rna ◽  
Base Composition ◽  
Buoyant Density ◽  
Main Band ◽  
Major Species ◽  
A Minor ◽  
Cytoplasmic Ribosomes

Polytoma obtusum has a main band DNA (alpha) with a buoyant density in CsC1 of rho = 1.711 g/ml and a light DNA satellite (beta) with rho = 1.682 g/ml. beta-DNA was substantially enriched in a fraction containing small leucoplast fragments and some mitochondria, which was obtained in a pellet sedimenting between 3,000 g and 5,000 g. A crude mitochondrial pellet was also obtained by sedimenting at 12,000 g to recover particulates remaining in the supernate after 10 min at 5,000 g. This fraction contained a third DNA component (gamma) with rho = 1.714 g/ml. We have concluded that the leucoplasts of P. obtusum contain the beta-DNA (1.6882) and the mitochondria possess the gamma-component (1.714). Two distinct classess of ribosomes were isolated and separated by sucrose density gradients, a major 79S species and a minor species at 75S. The major species possessed the 25S and 18S ribosomal RNA (rRNA), characteristic of cytoplasmic ribosomes, and these particles co-sedimented in sucrose gradients with the 79S cytoplasmic ribosomes of Chlamydomonas reinhardtii. The minor species was present in about 2% of the total ribosomal population but showed an eight-to-ninefold enrichment in the leucoplast pellet, suggesting that it was of organelle origin. These 73S particles had RNA components migrating very closely with the 18S and 25S species of the 79S ribosomes, but the base composition of the rRNA from these two classes of ribosomes was significantly different; the rRNA from the 79S ribosomes had a G+C mole ratio of 50.0%, while the rRNA from the 73S class had a ratio of 47.5%. By comparison, chloroplast ribosomes of C. reinhardtii were found to sediment at 70S and contain rRNA molecules of 23S and 16S, with a G + C content of 51.0%. These findings support the concept that the Polytoma leucoplast possesses characteristic genetic and protein-forming systems.

scholarly journals Characterization of cytoplasmic and nuclear genomes in the colorless alga Polytoma. III. Ribosomal RNA cistrons of the nucleus and leucoplast.

1976 ◽  
Vol 69 (2) ◽  
pp. 383-392 ◽  
Author(s):  
C Siu ◽  
K Chiang ◽  
H Swift
Keyword(s):  
Chlamydomonas Reinhardtii ◽  
Ribosomal Rna ◽  
Nuclear Dna ◽  
Buoyant Density ◽  
Nuclear Genome ◽  
The Other ◽  
Heterologous Hybridization ◽  
Other Hand ◽  
Specific Hybridization

The colorless alga Polytoma obtusum has been found to possess leucoplasts, and two kinds of ribosomes with sedimentation values of 73S and 79S. The ribosomal RNA (rRNA) of the 73S but not the 79S ribosomes was shown to hybridize with the leucoplast DNA (rho - 1.682 g/ml). Nuclear DNA of Polytoma (rho = 1.711) showed specific hybridization with rRNA from the 79S ribosomes. Saturation hybridization indicated that only one copy of the rRNA cistrons was present per leucoplast genome, with an average buoyant density of rho = 1.700. On the other hand, about 750 copies of the cytoplasmic rRNA cistrons were present per nuclear genome with a density of rho = 1.709. Heterologous hybridization studies with Chlamydomonas reinhardtii rRNAs showed an estimated 80% homology between the two cytoplasmic rRNAs, but only a 50% homology between chloroplast and leucoplast rRNAs of the two species. We conclude that the leucoplasts of Polytoma derive from chloroplasts of a Chlamydomonas-like ancestor, but that the leucoplast rRNA cistrons have diverged in evolution more extensively than the cistrons for cytoplasmic rRNA.

Characterization of Rapidly Labelled Nucleic Acids in Tissues of Plant Seedlings

1966 ◽  
Vol 21 (10) ◽  
pp. 983-992 ◽  
Author(s):  
Vera Hemleben-Vielhaben
Keyword(s):  
Nucleic Acids ◽  
Ribosomal Rna ◽  
Messenger Rna ◽  
Specific Activity ◽  
Supernatant Fraction ◽  
Nucleic Acid Metabolism ◽  
Tissue Homogenates ◽  
Fraction I ◽  
Plant Seedlings

The nucleic acid metabolism of plant tissues was examined by incubating seedlings of Phaseolus, Vicia, Pisum, and Soja or sections of them with 32P for short periods of time. The nucleic acids extracted from this material were fractionated on columns of methylated albumin coated on kieselgur, and the radioactivity and composition of the specific fractions were determined. Application of 32P to intact seedlings or to excised parts of seedlings resulted in the same pattern of labelled nucleic acids in all tissues, but the total amount of incorporated radioactivity was different. In all tissues investigated five rapidly labelled RNA fractions were found associated with the following components: (I) soluble RNAs, (II) DNA, (III—V) ribosomal RNA. Fraction I contained equally high amounts of CMP and GMP thus differing significantly from the soluble RNAs. The composition of fraction (II) which was probably bound to DNA in the form of a complex, was similar to that of fraction I provided the labelling period was short. Fractions III—V were of the ribosomal type. The rapidly labelled DNA fraction had a high guanine-cytosine content (60%) as compared with the bulk DNA (40%). Fractional centrifugation of the tissue homogenates revealed that the labelled RNA of the ribosomal type was partly associated with the ribosomes, partly with larger particles which were sedimented by low speed centrifugation. The RNA associated with the latter had a higher specific activity than the ribosomal RNA in the supernatant. Fraction I and the second component of the soluble RNA (s-2) were also confined to the sediment of larger particles. Actinomycin D (10 µg/ml) inhibited the incorporation of 32P in the nucleic acids. In chase experiments it caused a decrease in the specific activity of all RNA fractions, most prominently, however, in fraction I and II indicating their instability and resemblance to messenger RNA.

Isolation and Characterization of Ribosomal RNA from the Phycomycete Allomyces arbuscula / Isolation and Characterization of Ribosomal RNA from the Phycomycete Allomyces arbuscula

1975 ◽  
Vol 30 (3-4) ◽  
pp. 302-303 ◽  
Author(s):  
P. Fähnrich ◽  
H.H. Rothe ◽  
M. Trapp
Keyword(s):  
Ribosomal Rna ◽  
Base Composition ◽  
18S Rrna ◽  
Isolation And Characterization ◽  
Allomyces Arbuscula

Abstract The ribosomal RNA of the gametophyte of Allomyces arbuscula contains two components with sedimentation coefficients of approximately 25S and 18S. The percent base composition of 25S rRNA is 31/28/24/17 (U/G/A/C), that of 18S rRNA 34/28/22/16

scholarly journals RIBOSOME PRECURSOR PARTICLES IN NUCLEOLI

1969 ◽  
Vol 42 (1) ◽  
pp. 272-283 ◽  
Author(s):  
Ming C. Liau ◽  
Robert P. Perry
Keyword(s):  
Ribosomal Rna ◽  
Actinomycin D ◽  
Large Subunit ◽  
Cesium Chloride ◽  
Detectable Amount ◽  
Progressive Decrease ◽  
Rna Molecules ◽  
Gradual Shift ◽  
Cytoplasmic Ribosomes

Ribonucleoprotein (RNP) particles containing the precursors of ribosomal RNA were extracted from L cell nucleoli and analyzed under conditions comparable to those used in the characterization of cytoplasmic ribosomes. Using nucleoli from cells suitably labeled with 3H-uridine, we detected three basic RNP components, sedimenting at approximately 62S, 78S, and 110S in sucrose gradients containing magnesium. A fourth particle, sedimenting at about 95S, appears to be a dimer of the 62S and 78S components. When centrifuged in gradients containing EDTA, the 62S, 78S, and 110S particles sediment at about 55S, 65S, and 80S, respectively. RNA was extracted from RNP particles which were prepared by two cycles of zonal centrifugation. The 62S particles yielded 32S RNA and a detectable amount of 28S RNA, the 78S structures, 32S RNA and possibly some 36S RNA, and the 110S particles, a mixture of 45S, 36S, and 32S RNA's. When cells were pulsed briefly and further incubated in the presence of actinomycin D, there was a gradual shift of radioactivity from heavier to lighter particles. This observation is consistent with the scheme of maturation: 110S → 78S → 62S. The principal buoyant densities in cesium chloride of the 110S, 78S, and 62S particles are 1.465, 1.490, and 1.545, respectively. These densities are all significantly lower than 1.570, which is characteristic of the mature large subunit of cytoplasmic ribosomes, suggesting that the precursor particles have a relatively higher ratio of protein to RNA, and that ribosome maturation involves, in addition to decrease in the size of the RNA molecules, a progressive decrease in the proportion of associated protein.

scholarly journals Keratin Biosynthesis II. Extraction and Characterization of Nucleic Acids from Wool Roots

1970 ◽  
Vol 23 (1) ◽  
pp. 139 ◽  
Author(s):  
BR Wilkinson
Keyword(s):  
Nucleic Acids ◽  
Ribosomal Rna ◽  
Good Yield ◽  
Two Stage ◽  
Extraction Procedures ◽  
Yield And Purity

Ribosomal RNA (rRNA), soluble RNA (sRNA), and DNA have been extracted from wool roots in good yield and purity. rRNA and sRNA were prepared by extracting wool roots with a hydrophilic salt and a phenol-cresol mixture and rRNA was selectively precipitated with m�cresol. DNA was extracted with a salt having lipophilic and chelating properties, together with the phenol-cresol mixture. Two�stage extraction procedures were essential for the preparation of stable, undegraded nucleic acids.

scholarly journals Characterization of messenger-like ribonucleic acid from Saccharomyces cerevisiae by the use of chromatography on methylated albumin–kieselguhr

1970 ◽  
Vol 119 (4) ◽  
pp. 699-706 ◽  
Author(s):  
Roger Johnson
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Protein Synthesis ◽  
Carbon Source ◽  
Ribosomal Rna ◽  
Sodium Dodecyl ◽  
Nucleotide Composition ◽  
The Other ◽  
Dilute Solution ◽  
A Minor

Chromatography on methylated albumin–kieselguhr of RNA from Saccharomyces cerevisiae was used to separate stable RNA from a tenaciously bound DNA-like RNA fraction. The tenaciously bound RNA, which was eluted with a dilute solution of sodium dodecyl sulphate, was characterized as messenger-like RNA by its sedimentation behaviour, nucleotide composition, lack of methylated bases and labelling kinetics. Chromatography of purified ribosomal RNA indicated a minor contamination of the tenaciously bound fraction with ribosomal RNA. On the other hand, a large portion of pulse-labelled polyribosomal RNA from protoplasts of Saccharomyces cerevisiae was tenaciously bound to the columns. The `chase' of isotopic label from the messenger-like RNA was found to be retarded during inhibition of protein synthesis both by cycloheximide and by starvation for a carbon source.

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