Metabolism of high molecular weight, polydisperse, rapidly labeled nuclear RNA in rat liver

1968 ◽  
Vol 46 (12) ◽  
pp. 1497-1505 ◽  
Author(s):  
Maurice Brossard ◽  
Louis Nicole
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Rat Liver ◽  
Ribosomal Rna ◽  
Base Composition ◽  
Orotic Acid ◽  
Chromosomal Origin ◽  
Base Analysis ◽  
Nuclear Rna ◽  
Kinetics Of

Studies of the metabolism of rat liver RNA showed the existence of two species of rapidly labeled nuclear RNA: a 45 S preribosomal type of nucleolar origin, and a 6–50 S polydisperse RNA of chromosomal origin. The kinetics of labeling with orotic acid-14C and the nature of the latter RNA have been investigated. The following findings are reported, (1) This RNA is composed of at least four main classes of RNA having sedimentation coefficients of approximately 45, 35, 24, and 18 S. (2) Except for the 18 S class which seems to be an end product, the three other classes have a rapid turnover and do not appear to leave the nucleus. (3) Base analysis after 32P incorporation indicates that these four classes of RNA have a similar base composition with a G+C/A + U ratio in the range of 0.98–1.07, which resembles DNA more closely than ribosomal RNA. (4) The 6–50 S polydisperse RNA has a different metabolism than that of the 45 S preribosomal type and there is no precursor-to-product relationship between these two species of RNA.

Effect of growth hormone and hydrocortisone on the synthesis of rapidly labeled, high molecular weight, nuclear RNA in rat liver

1969 ◽  
Vol 47 (2) ◽  
pp. 226-229 ◽  
Author(s):  
Maurice Brossard ◽  
Louis Nicole
Keyword(s):  
Molecular Weight ◽  
Growth Hormone ◽  
High Molecular Weight ◽  
Rat Liver ◽  
Orotic Acid ◽  
The Other ◽  
Other Hand ◽  
Nuclear Rna ◽  
Nucleolar Rna

The effects of growth hormone and hydrocortisone on the synthesis of rat liver RNA have been studied. Administration of growth hormone stimulated the incorporation of 14C-orotic acid into 45 S preribosomal nucleolar RNA, and had no effect on the 6–50 S polydisperse nuclear RNA of extra-nucleolar origin. On the other hand, hydrocortisone stimulated the synthesis of all types of nuclear RNA, but mainly that of the 18 S class of 6–50 S polydisperse nuclear RNA.

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 MITOCHONDRIAL RNA FROM CULTURED ANIMAL CELLS

1970 ◽  
Vol 46 (2) ◽  
pp. 245-251 ◽  
Author(s):  
Bland S. Montenecourt ◽  
Margaret E. Langsam ◽  
Donald T. Dubin
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Cell Lines ◽  
Ribosomal Rna ◽  
Gel Electrophoresis ◽  
Base Composition ◽  
Size Class ◽  
Mitochondrial Rna ◽  
Animal Cells ◽  
Molecular Weights

Discrete RNA fractions sedimenting slightly slower than 18s ribosomal RNA have been found in mitochondrial preparations from both hamster (BHK-21) and mouse (L-929) cells. This RNA could be separated into two components, present in approximately equimolar amounts, by prolonged zonal centrifugation or acrylamide gel electrophoresis. The hamster components had sedimentation constants averaging 16.8 and 13.4, and molecular weights (estimated by gel electrophoresis) averaging 0.74 and 0.42 x 106 daltons. Mixed labeling experiments showed that the mouse components sedimented and electrophoresed 3–6% more slowly than the corresponding hamster components. The RNA from both cell lines resembled mitochondrial ribosomal RNA from yeast and Neurospora in being GC poor, and in addition the larger and smaller components resembled each other in base composition. These results, taken with those of other recent studies, are compatible with the idea that our high molecular weight mitochondrial RNA is ribosomal; such RNA would then constitute a uniquely small size-class of ribosomal RNA.

scholarly journals Characterization of uterine heterogeneous nuclear ribonucleic acid and the effect of oestradiol-17β on its synthesis

1978 ◽  
Vol 172 (3) ◽  
pp. 587-593 ◽  
Author(s):  
S Aziz ◽  
J T Knowler
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Early Response ◽  
Oestrogen Treatment ◽  
Size Profile ◽  
Immature Rats ◽  
Nuclear Rna ◽  
Kinetics Of ◽  
Molecular Weight Fractions

An early response to the administration of oestradiol-17 beta to immature rats is a dramatic stimulation in the synthesis of uterine hnRNA (heterogenous nuclear RNA). High-molecular-weight fractions of the hnRNA were purified and subfractionated on poly(U)-Sepharose into fractions that differed in their poly(A) content and their size profile on polyacrylamide gels. Oestrogen treatment of the rats stimulated the synthesis of all three fractions of high-molecular-weight hnRNA, but the kinetics of synthesis, degree of stimulation and size distribution of the newly synthesize RNA differed in each fraction.

scholarly journals Thermal Degradation Kinetics and Modeling Study of Ultra High Molecular Weight Polyethylene (UHMWP)/Graphene Nanocomposite

Molecules ◽  
2021 ◽  
Vol 26 (6) ◽  
pp. 1597
Author(s):  
Iman Jafari ◽  
Mohamadreza Shakiba ◽  
Fatemeh Khosravi ◽  
Seeram Ramakrishna ◽  
Ehsan Abasi ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Molecular Weight ◽  
Thermal Degradation ◽  
High Molecular Weight ◽  
Degradation Kinetics ◽  
Graphene Nanosheets ◽  
Thermal Degradation Kinetics ◽  
Graphene Nanocomposites ◽  
Kinetics Of ◽  
Ultra High Molecular Weight

The incorporation of nanofillers such as graphene into polymers has shown significant improvements in mechanical characteristics, thermal stability, and conductivity of resulting polymeric nanocomposites. To this aim, the influence of incorporation of graphene nanosheets into ultra-high molecular weight polyethylene (UHMWPE) on the thermal behavior and degradation kinetics of UHMWPE/graphene nanocomposites was investigated. Scanning electron microscopy (SEM) analysis revealed that graphene nanosheets were uniformly spread throughout the UHMWPE’s molecular chains. X-Ray Diffraction (XRD) data posited that the morphology of dispersed graphene sheets in UHMWPE was exfoliated. Non-isothermal differential scanning calorimetry (DSC) studies identified a more pronounced increase in melting temperatures and latent heat of fusions in nanocomposites compared to UHMWPE at lower concentrations of graphene. Thermogravimetric analysis (TGA) and derivative thermogravimetric (DTG) revealed that UHMWPE’s thermal stability has been improved via incorporating graphene nanosheets. Further, degradation kinetics of neat polymer and nanocomposites have been modeled using equations such as Friedman, Ozawa–Flynn–Wall (OFW), Kissinger, and Augis and Bennett’s. The "Model-Fitting Method” showed that the auto-catalytic nth-order mechanism provided a highly consistent and appropriate fit to describe the degradation mechanism of UHMWPE and its graphene nanocomposites. In addition, the calculated activation energy (Ea) of thermal degradation was enhanced by an increase in graphene concentration up to 2.1 wt.%, followed by a decrease in higher graphene content.

U1 small nuclear RNA-like sequences in human high molecular weight RNA

1984 ◽  
Vol 122 (2) ◽  
pp. 838-844 ◽  
Author(s):  
J.M. Capasso ◽  
M.A. Docherty ◽  
A. Ray ◽  
E.D. Kaplan ◽  
G.L. Eliceiri
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Small Nuclear Rna ◽  
Nuclear Rna
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