Cytoplasmanukleotide in eiweissproduzierenden Dr�senzellen

Caspersson, T.; Landström-Hydén, H.; Aquilonius, L.

doi:10.1007/bf00325956

Cited by 96 publications

(13 citation statements)

References 20 publications

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“…Caspersson (10) has formulated a general rule for the synthesis of cytoplasmic ribonucleic acid which places this synthesis under the control of nuclear factors. The first change which he has found in actively synthesizing ceils, pancreatic exocrine cells included (11), is an enlargement of the nucleolus, with an accumulation of ribonucleic acid and histone therein. Caspersson has postulated that there follows a diffusion of the histone through the nuclear membrane, where it activates the production of cytoplasmic ribonucleoprotein.…”

Section: Discussionmentioning

confidence: 99%

The Ergastoplasm

Weiss

1953

Journal of Experimental Medicine

169

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The basophllic material in the base of the pancreatic cell was named ergastoplasm by Gamier (21) because of its close association with the synthetic activity of the cell. Observations by Caspersson (10), Brachet (7), and others (13,24,25) have provided strong evidence that cytoplasmic nucleoproteins, the basophilic substances of the ergastoplasm, participate in the synthesis of proteins. The morphological and chemical details of the relationship between ergastoplasm and protein synthesis have remained obscure, however, in part because of the low resolving power of the ordinary microscope and in part because protein synthesis in ~/tro has not been accomplished. With the increased resolution of the electron microscope it should be possible to reexamine the relationships between the ergastoplasm and protein synthesis.These relationships have been studied in the exocrine portion of the pancreas of Swiss albino mice. Mice were fasted, and their pancreatic cells thus depleted of ergastoplasm and secretion granules. The animals were subsequently fed, and the formation of these elements was traced in detail. Observations made in the course of these and ancillary experiments indicate that the ergastoplasm is composed of sacs of variable structure, the membranous walls of which contain ribonucleic acid. New ergastoplasmic sacs appear mainly within cytoplasmic centers and also, but much less frequently, in apposition to the nuclear membrane, and possibly in relation to the basal plasma membrane. Small ergastoplasmic sacs, at first apparently empty, later accumulate material within their lumens, and become transformed into the well known secretion granules. Materials and MetkodsTen to 20 week-old Swiss albino mice were used in all the experiments. The animals were killed by decapitation, and a sm~|l piece of pancreas was obtained within 2 minutes of the

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Section: Discussionmentioning

confidence: 99%

The Ergastoplasm

Weiss

1953

Journal of Experimental Medicine

169

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“…Similarly, following the suggestion of Caspersson and coworkers that cytoplasmic nucleoprotein is associated with rapid cell growth (52,53) and pancreatic cell synthesis of protein secretion (54,55), LandstrSm, Caspersson, and Wohlfart (45) have drawn an interesting analogy between egg cells and nerve cells. Both cell types have considerable cytoplasmic nucleoprotein and large nucleolus, and both undergo a period of great growth.…”

Section: Present Knowledge Oj the Nissl Substancementioning

confidence: 95%

The Regenerative Cycle of Motoneurons, With Special Reference to Phosphatase Activity

Bodian

Mellors

1945

Journal of Experimental Medicine

182

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1. The regenerative cycle of motoneurons after axon amputation is described, and an attempt made to correlate morphological and chemical events in cell bodies with the growth requirements of regenerating axons. 2. The "normal" pattern of Nissl material in the cell is considered to be the resultant of a steady state in cytoplasmic nucleoprotein. Chromatol is then interpreted as a shift of the balance of nucleoprotein turnover in fa of degradation. The rapid early depletion of Nissl substance in chromatolysis is ascribed to the increased growth requirements created by the active early sprouting of the regenerating axon. Acid phosphatase activity begins to increase above normal levels during this period in the region of nucleopro degradation. 3. The recovery period of chromatolysis due to axon section coincide in time with the phase of gradual lengthening of the regenerating axon, and is thought to represent a gradual restoration of the balance of nucleoprotein degradation and synthesis. During this period acid phosphatase activity is at its height in the region of transformation of Nissl substance, later declines to normal levels when the original pattern of Nissl bodie is restored. 4. The transformation of cytoplasmic nucleoprotein which occurs in chromatolysis after axon section, with the probable liberation (46), and depletion (44), of nucleotides, associated with acid phosphatase activity, suggests the hypothesis that liberated nucleotides or nucleotide compounds may pass down the axon in which they take part in enzymatic activity associated with growth and organization of the newly formed axon. This type of activity would not be incompatible with the ideas previously expressed (30, 81) of a continual function of Nissl substance in maintaining the integrity of the large volume of cytoplasm represented by the axon, as well perhaps as the associated myelin sheath.

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“…In their first claims about these proteins Caspersson and his colleagues referred to them as of "histone type" because it was supposed by them that the ultraviolet absorption spectrum of a histone differs from that of other proteins, being shifted somewhat to longer wave lengths and this seemed to account for the absorption at these wave lengths which they reported in regions of cells rich in ribonucleic acid (10). When the absorption spectra of satisfactory histone preparations were determined, it was found, however, that the maximum of the ultraviolet absorption spectrum of a histone does not differ from that of the generality of proteins (II).…”

Section: Introductionmentioning

confidence: 99%

Synthesis of Protein in the Pancreas

Allfrey

Daly

Mirsky

1953

Journal of General Physiology

140

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1. The ribonucleoprotein of the microsome fraction which sediments at 40,000 R.P.M. as a pellet (and which is referred to as the pellet material) has been studied with reference to its role in protein synthesis in the pancreas. 2. In pellet material nucleic acid and protein form a definite complex as shown by its electrophoretic behavior and unchanging composition under various conditions. 3. Protein of pellet material is not especially rich in the diamino acids. 4. Evidence is brought forward indicating that the protein component of pellet material takes part in the general process of protein synthesis in the cell. (a) The well known correlation between quantity of RNA and rate of protein synthesis in a tissue implicates the protein of the pellet material, for most of the RNA in the pancreas and other tissues is in this material. (b) Uptake of isotopically labelled glycine by the pellet material, confirming results of previous workers, is for short periods greater than in other protein fractions. (c) Comparing the pellet materials of pancreas, liver, and kidney—three tissues with vastly different rates of protein synthesis, in the sequence given—there is a correlation between the quantity of RNA in the pellet and the rate of protein synthesis in the tissue; a similar correlation between quantity of RNA in the pellet material and rate of N15-glycine uptake by the protein component of the pellet; and finally, the level of uptake by total protein varies with the tissue and is related to the uptake of N15-glycine by protein of the pellet. 5. In the pancreas a distinction can be made between proteins synthesized for secretion and the nucleoprotein of the pellet (not found in the secretion) which, however, takes part in the synthetic process, as shown by the fact that the N15 uptake by protein of the pellet is increased when the synthesis of digestive enzymes is stimulated by secretion. 6. The time course of N15 uptake by proteins of the pancreas indicates that pellet protein serves as precursor material in the synthesis of the secretory proteins. 7. Rate of uptake of N15-glycine by the purines of RNA of the pellet material is not correlated with uptake by the protein. 8. The uptake of C14-alanine by an in vitro system of microsomes + mitochondria is impaired by preincubation of the microsomes with ribonuclease. This is direct experimental evidence for the dependence of protein synthesis upon the presence or intactness of ribonucleic acid in the microsomes.

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Cytoplasmanukleotide in eiweissproduzierenden Dr�senzellen

Cited by 96 publications

References 20 publications

The Ergastoplasm

The Ergastoplasm

The Regenerative Cycle of Motoneurons, With Special Reference to Phosphatase Activity

Synthesis of Protein in the Pancreas

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