Giant-size rapidly labeled nuclear ribonucleic acid and cytoplasmic messenger ribonucleic acid in immature duck erythrocytes

( R e p le 2 aoDt 1967/6 dkcembre 1967) I . Nuclear and cytoplasmic RNA from sheep thyroid slices in vitro labeled with [3H]uridine or [32P]phosphate from 5 min up to 9 h, have been obtained by different phenol extraction procedures. Early-labeled RNA was only extracted by phenol containing 0.1 or lo/, (w/v) sodium dodecylsulfate (SDS) at 0" or 60°, whereas stable nuclear or polysomal RNA was easily extracted by phenol at 0".2. Time course of incorporation of label into subcellular particles has shown the early labeling of nuclear RNA and the transfer of radioactivity into the cytoplasm.3. Rapidly-labeled RNA extracted from nuclei by phenol-I O/, (w/v) SDS and analyzed by sedimentation was shown to sediment in three discrete classes 50-30 S, 22 S and 13 S, different from ribosomal RNA. After 9 h o f incubation the 22 S and 13 S labeled RNAs were still present in detectable amounts in the nuclei, indicating a somewhat low turnover rate for these components. 4.The kinetics of incorporation of label into polysomes was studied in thyroid slices incubated from 15 min up to 5 h with [3H]uridine or [32P]phosphate. RNA was dissociated from polysomes by dodecylsulfate treatment and centrifuged on sucrose gradient. As for nuclei, the rapidlylabeled RNAs sediment in discrete size classes, 22 S and 13 S. After a long incubation time (5 h) the label was predominant in 28 S and 18 S ribosomal RNA but 28 S RNA was not completely labeled. Up to 30 min labeling a high molecular weight, early-labeled RNA was present in purified polysomes. Its radioactivity declines after 60 min labeling.5. A part of the rapidly labeled polysomal RNA can be reversibly separated from rRNP by the action of EDTA (1.25 to 5 pmoles EDTA/mg RNP). It sediments in a broad zone (12-30 S) of high specific radioactivity. Increasing Mg++ concentration results in the reassociation of rapidly-labeled RNA to ribosomal sub-particles.6. Buoyant densities of the polysomal RNP particles obtained by EDTA treatment of 32P-labeled polysomes and stabilized by means of formaldehyde fixation, were determined by banding in CsCl gradients. The bulk o f the stable material banded at characteristic densities (d = 1.55 and 1.48), but most of the rapidly-labeled RNA banded at d = 1.38.The specific radioactivity of this material was the same as that of the 12-30 S RNA isolated by sucrose gradient centrifugation from the same EDTA-treated polysomes. Preliminary double labeling experiments and computation of the RNA to protein ratio calculated from the RNA and protein density values indicate this material to be early-labeled nucleoprotein particles with a high protein content.La glande thyroide est un tissu dont la fonction essentielle est la synthhse des hormones thyroidiennes. Morphologiquement la d86renciation du tissu thyroidien se manifeste par une structure folliculaire trhs caractkristique. Chaque follicule est constitu6 [12] le poids moleculaire des sousunites obtenues par dissociation de la thyroglobuline reduite et 8-carboxymethylee serait de 110.000 B 125.000, indiquan...

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“…La Fig.11 [49,50]. Des travaux anterieurs sur la nature ct la biosynthese des RNA des cellules animales ont Bt6 passes en revue reeemment [51].…”

unclassified

Acides ribonucléiques messagers de la glande thyroïde

Cartouzou

Attali

Lissitzky

1968

European Journal of Biochemistry

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“…Since erythropoiesis in the adult chicken occurs mainly in the bone marrow, all six maturation stages may be found there, whereas only the later stages usually appear in the circulating blood [19,33,34]. Thus in the present work, erythrocytes from the blood of normal chickens contained the order of 2 t o 5O/, immature cells, all late polychromatic erythrocytes.…”

Section: Sources Of Immature Erythoid Cellsmentioning

confidence: 46%

A Study of the Quantitative Variation of Histones, and Their Relationship to RNA Synthesis, during Erythropoiesis in the Adult Chicken

Billett

Hindley

1972

European Journal of Biochemistry

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Defined cell populations representing limited periods in the erythropoietic sequence of adult chickens have been obtained by buoyant density centrifugation of bone marrow cells on bovine serum albumin gradients. The histones of these various populations and of circulating erythrocytes have been compared quantitatively by polyacrylamide gel electrophoresis. No change in the relative amounts of Fi, F2a1, F2a2 (and possibly F3+2b), could be detected between the early polychromatic erythrocyte and the mature erythrocyte, although changes in the distribution of the Fi subfractions were observed. The amount of the erythrocyte specific histone (F2c), however, increases approximately 2.5-fold during this period. These events were correlated with a parallel decrease in RNA synthesis, both in whole cells and when measured in isolated nuclei. The results are discussed in relation to possible mechanisms of chromatin condensation and genome repression.

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“…This RNA class is extremely polydisperse in molecular weight and metabolically unstable its half-life does not exceed 30 mm [2,4,5] . This presumes that in about 3 h not more than 1% of the newly formed HnRNA should remain in the nuclei.…”

Section: Introductionmentioning

confidence: 99%