Observations sur le rôle biochimique du nucléole

Baltus, Elyane

doi:10.1016/0006-3002(54)90068-2

Cited by 53 publications

(7 citation statements)

References 16 publications

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“…One factor necessary to mitochondrial function has been shown to be synthesized in the nucleus. Hogeboom and Schneider (23) have demonstrated that the coenzyme DPN is synthesized by a nuclear enzyme, while Baltus (24) has localized this enzyme in the starfish oocyte nucleoli. Frederic and Ch6vremont (10,11), from observations on living cells, described the nucleolus as moving to the side of the nucleus where the mitochondria have attached.…”

Section: Discussionmentioning

confidence: 99%

Mitochondria

Brandt

Pappas

1959

The Journal of Cell Biology

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This study has demonstrated that in the ameba, Pelomyxa carolinensls Wilson (Chaos chaos L.) the limiting membranes of mitochondria and postdivision nuclei are often continuous. The morphological relationship may be functional in that it permits an exchange of material resulting directly or indirectly in an increased enzyme content of the mitochondria. It is suggested that through a series of progressive foldings of its envelope, the nucleus may be a site of formation of mitochondria.

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Section: Discussionmentioning

confidence: 99%

Mitochondria

Brandt

Pappas

1959

The Journal of Cell Biology

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“…From the work of Allfrey and his coworkers (5-10), Rendi (11), and Wang (12), who have studied isolated nuclei and extracts from such nuclei, much has been learned about the biochemical apparatus of nuclear protein synthesis and about its basic similarities to the cytoplasmic ribosomal apparatus. In many laboratories the combination of the cytological and biochemical approach has been achieved by isolating subnuclear components such as nucleoli (13)(14)(15)(16)(17), but these methods have not yet been extended to protein synthesis.…”

Section: Introductionmentioning

confidence: 99%

Protein Synthesis by Isolated Pea Nucleoli

Birnstiel

Hyde

1963

The Journal of Cell Biology

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A new method is described for the preparation of active, nucleus-free nucleoli and chromatin in relatively high purity and in sufficient quantities to permit biochemical and electron microscopic investigation. This method consists of disintegrating previously isolated nuclei by grinding with glass beads in an isotonic medium thus liberating structurally intact nucleoli and chromatin threads. Nucleoli and chromatin are then purified by differential centrifugation in Ficoll solutions. A study of the chemical composition, submicroscopic structure, and biological activity of the nucleolar preparation has been made. An equivalent study of the chromatin material has also been carried out in order to assess the significance of chromosomal contamination in nucleolar protein synthesis. The isolated nucleoli rapidly incorporate leucine-C 14 into acid and base stable compounds in vitro. Such incorporation lasts for 20 minutes at 37°C and is enhanced by the addition of an energy-regenerating system and a complete amino acid mixture. It is independent of the nuclear pH 5 enzymes. The bulk of the incorporated label is recovered in the residual, ribosome-like nucleolar protein fraction and a small percentage is found in the acid-extractable basic proteins. The rate of protein synthesis by isolated nucleoli is more rapid than that occurring in the chromatin fraction. This is taken as an additional proof that the nucleolus is the principal site of protein synthesis in the interphase pea nucleus. I N T R O D U C T I O NIn recent years intranuclear protein synthesis has attracted considerable attention. In particular, the role of the nuclcolus and the chromatin has been under scrutiny. Thus Ficq (1) and others found the nucleolus to be thc most active site for protein synthesis. This finding has been disputed, notably by Carneiro and Leblond (2), and has led to considerablc controversy. A discussion of these results, obtained by the tcchniques of autoradiography, is found in recent reviews by Sirlin (3, 4).From the work of Allfrey and his coworkers (5-10), Rendi (11), and Wang (12), who have studied isolated nuclei and extracts from such nuclei, much has been learned about the biochemical apparatus of nuclear protein synthesis and about its basic similarities to the cytoplasmic ribosomal apparatus. In many laboratories the combination of the cytological and biochemical approach has been achieved by isolating subnuclear components such as nucleoli (13-17), but these methods have not yet been extended to protein synthesis.In previous publications we have described amino acid incorporation by isolated pea nuclei (18). Fractionation of such nuclei (19) has established the nucleolus as the principal site of nuclear protein synthesis (20,21). We now wish to show that nucleus-free preparations of isolated nucleoli of relatively high purity are able to incorporate labeled amino acids into protein and that such in-41 on

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“…2) that the level of non-protein nitrogen compounds is higher in non-nucleated than in nucleated parts (Brachet et al, 1955). There are good reasons to believe that some of the nucleotide coenzymes (especially DPN) originate in the nucleus: Several enzymes required for this synthesis are localized in the nucleus of liver cells (Hogeboom and Schneider, 1952;Stern et al, 1952) and in the nucleoli of starfish ooeytes (Baltus, 1954).…”

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confidence: 99%