Experiments With N15 on Purines From Nuclei and Cytoplasm of Normal and Regenerating Liver

Bergstrand, Anders; Eliasson, N. A.; Hammarsten, E.; Nordberg, Bo; Reichard, Peter; Ubisch, H. von

doi:10.1101/sqb.1948.013.01.006

Cited by 47 publications

(5 citation statements)

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“…Incorporation into D N A is low, into histone higher, and into residual protein much higher still, being comparable with that into mixed cytoplasmic protein. The low rate of incorporation by DNA of liver nuclei is in accord with the experience of other investigators (8)(9)(10). The rate of incorporation by the DNA of pancreas nuclei is about the same, but that of kidney is much lower, being 0.007 under the same conditions.…”

supporting

confidence: 90%

“…The possibility that the DNA of this experiment was contaminated with RNA was considered, but tests showed that no such contamination was present. It was found by previous investigators that the N is of glycine is incorporated far more rapidly into the total nuclear protein of liver than into DNA (8). From the present experiments it can be seen that the rate of incorporation varies considerably in the different protein fractions of the nucleus.…”

supporting

confidence: 62%

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Uptake of Glycine-N15 by Components of Cell Nuclei

Daly

Allfrey

Mirsky

1952

Journal of General Physiology

101

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An indication of the relative metabolic activities of various components of the cell nucleus is given by the rates at which they take up the nitrogen of glycine labelled with N 16. The nudear components which we have examined in the work here reported are desoxyribonudeic acid (DNA) and two protein fractions, histone and residual protein. Nuclear components of two kinds of cells have been studied: those of mammalian liver and pancreas, tissues with high metabolic rates; and those of avian erythrocytes and echinoderm sperm, cells with relatively low rates of metabolism.No other nuclear components than DNA, histone, and residual protein were studied because nuclei were isolated by the citric acid procedure, in the course of which much material is removed from nuclei (1). When nuclei are isolated from liver or pancreas with citric acid, as much as SS per cent of their protein may be extracted. For an understanding of the role of the nucleus in the metabolism of the cell, it would be of interest to know how rapidly N 1~ is taken up by these proteins as well as by histone and residual protein.To obtain these readily extracted proteins, nuclei must be isolated in nonaqueous media. The isolation of clean nuclei by means of non-aqueous solvents is, however, far more difficult that it is with citric acid. The substances that remain in citric acid nuclei are of considerable interest so that the rate at which N 16 of glycine is incorporated into them should be determined. DNA and histone have been known since the work of Miescher and Kossel. Residual protein has been identified more recently (2). The residual protein of isolated chromosomes is the insoluble protein that remains after all histone has first been removed at pH 3.8 by M NaCl and DNA subsequently removed by the action of desoxyribonudease (DNAase). It is an essential structural component of chromosomes. That it is actually protein is shown by analysis, for at least 90 per cent of it consists of various amino acids (3).DNA, histone, and residual protein are distributed in quite different ways in the nuclei from various tissues of the same organism. Nuclei from different tissues have been found to have a constant quantity of DNA per nucleus, a constant characteristic of the species. This is dearly seen when the nuclei of liver and red cells are compared. Different as these cells are, the DNA content per nucleus is the same in both (4). The quantity of histone does not 173

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supporting

confidence: 90%

supporting

confidence: 62%

Uptake of Glycine-N15 by Components of Cell Nuclei

Daly

Allfrey

Mirsky

1952

Journal of General Physiology

101

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“…Experiments on the incorporation of labelled precursors into different RNA fractions have consistently shown that the rate of incorporation of various precursors is higher into the RNA contained in the nucleus, and especially in the nucleolus, than into the cytoplasmic RNA fraction (Marshak, 1948;Marshak and Calvet, 1949;Jeener and Szafarz, 1950;Barnum and Huseby, 1950;Hurlbert and Potter, 1952;Bergstrand et al, 1948;Payne et al, 1952;Smellie et al, 1953). This does not prove, however, that nuclear RNA is the precursor of cytoplasmic RNA.…”

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confidence: 99%

The Function of the Nucleus in the Synthesis of Cytoplasmic Proteins

Brachet¹,

Chantrenne²

1956

Cold Spring Harbor Symposia on Quantitative Biology

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“…The lysine-rich histones do not precipitate in the range about pH 10.5, and so would not have been included in the present determinations. Low N 15 uptake by histones may, on the other hand, be due to the fact that they are combined with DNA, a substance showing an exceedingly low turnover in non-dividing cells (8,(10)(11)(12).…”

mentioning

confidence: 99%

“…The extract was dialyzed against water, and the histone precipitated by the addition of alkali to pH 10,6. To insure complete precipitation of histone it was necessary to allow the suspension to stand for one-hal/hour at room temperature or slightly above.…”

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confidence: 99%

Some Observations on Protein Metabolism in Chromosomes of Non-Dividing Cells

Allfrey

Daly

Mirsky

1955

The Journal of General Physiology

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In ceils of the liver and pancreas of mature animals (in which few dividing cells are present) the bulk of protein synthesis occurs in the cytoplasm (1-4 and 6). The experiments to be described in this paper show that under certain circumstances syntheses of protein in the cytoplasm and in the chromosomes are correlated. In these experiments, which were done on mice, protein metabolism was varied by fasting and subsequent feeding, rates of protein synthesis being low in a period of fasting and rising when feeding was resumed.Changes in protein metabolism were followed by injecting glycine labelled with N ~s. Both rates of uptake of N 15 by proteins of the cell and also of retention of N ~5, previously incorporated, were measured. Each protein fraction takes up more and more N 15, reaching a maximum, and then gradually loses what it has taken up. Uptake of NlS-glycine is considered to involve protein synthesis, although the possibility of exchange reactions should also be considered. Retention of N~6-glycine may simply be a measure of loss of labelled protein by the cell, but under certain conditions it may also be an indication of protein synthesis.Tissue proteins of both nucleus and cytoplasm were examined for their N 15 contents. Cytoplasmic proteins were obtained from sucrose homogenates. Unbroken cells, nuclei, and mitochondria were discarded, and two fractions were retained: the pellet material which sediments by centrifugation at high speed, in which much of the cytoplasmic nucleoprotein is found (5); and the protein remaining in the supemate after high-speed centrifugation, a fraction which, in the pancreas, is rich in the secretory enzymes (6). To obtain nuclear proteins, the nuclei were first isolated by the citric acid procedure (7). In the course of isolation by this procedure certain proteins are unfortunately extracted from nuclei and lost. Histone and "residual protein," both constituents of chromosomes, are, however, retained in the nuclei, and these proteins were isolated.It should first be noted in a general way how the various protein components compare in their uptake of N 15. These differences in rate of uptake have already been described in previous papers (I-4, 6, and 8) and they can be seen in any of the tables of this paper. In the pancreas cytoplasmic ribonucleoprotein has 415

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Experiments With N15 on Purines From Nuclei and Cytoplasm of Normal and Regenerating Liver

Cited by 47 publications

References 0 publications

Uptake of Glycine-N15 by Components of Cell Nuclei

Uptake of Glycine-N15 by Components of Cell Nuclei

The Function of the Nucleus in the Synthesis of Cytoplasmic Proteins

Some Observations on Protein Metabolism in Chromosomes of Non-Dividing Cells

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